Category: computers suck

  • Adding speech to MMBasic

    Yup, it’s another “let’s wire up a SYN6988 board” thing, this time for MMBasic running on the Armmite STM32F407 Module (aka ‘Armmite F4’). This board is also known as the BLACK_F407VE, which also makes a nice little MicroPython platform.

    Uh, let’s not dwell too much on how the SYN6988 seems to parse 19:51 as “91 minutes to 20” …

    Wiring

    SYN6988Armmite F4
    RXPA09 (COM1 TX)
    TXPA10 (COM1 RX)
    RDYPA08
    your choice of 3.3 V and GND connections, of course

    Where to buy: AliExpress — KAIKAI Electronics Wholesale Store : High-end Speech Synthesis Module Chinese/English Speech Synthesis XFS5152 Real Pronunciation TTS

    Yes, I know it says it’s an XFS5152, but I got a SYN6988 and it seems to be about as reliable a source as one can find. The board is marked YS-V6E-V1.03, and even mentions SYN6988 on the rear silkscreen:

    Code

    REM                 SYN6988 speech demo - MMBasic / Armmite F4
    REM                 scruss, 2023-07
    
    OPEN "COM1:9600" AS #5
    REM                 READY line on PA8
    SETPIN PA8, DIN, PULLUP
    
    REM    you can ignore font/text commands
    CLS
    FONT 1
    TEXT 0,15,"[v1]Hello - this is a speech demo."
    say("[v1]Hello - this is a speech demo.")
    TEXT 0,30,"[x1]soundy[d]"
    say("[x1]soundy[d]"): REM    chimes
    TEXT 0,45,"The time is "+LEFT$(TIME$,5)+"."
    say("The time is "+LEFT$(TIME$,5)+".")
    END
    
    SUB say(a$)
      LOCAL dl%,maxlof%
      REM     data length is text length + 2 (for the 1 and 0 bytes)
      dl%=2+LEN(a$)
      maxlof%=LOF(#5)
      REM     SYN6988 simple data packet
      REM      byte  1 : &HFD
      REM      byte  2 : data length (high byte)
      REM      byte  3 : data length (low byte)
      REM      byte  4 : &H01
      REM      byte  5 : &H00
      REM      bytes 6-: ASCII string data
      PRINT #5, CHR$(&hFD)+CHR$(dl%\256)+CHR$(dl% MOD 256)+CHR$(1)+CHR$(0)+a$;
      DO WHILE LOF(#5)<maxlof%
      REM       pause while sending text
        PAUSE 5
      LOOP
      DO WHILE PIN(PA8)<>1
        REM       wait until RDY is high
        PAUSE 5
      LOOP
      DO WHILE PIN(PA8)<>0
        REM       wait until SYN6988 signals READY
        PAUSE 5
      LOOP
    END SUB
    

    For more commands, please see Embedded text commands

    Heres the auto-translated manual for the SYN6988:

  • Markedly less success with three TTS boards from AliExpress

    Markedly less success with three TTS boards from AliExpress

    The other week’s success with the SYN6988 TTS chip was not repeated with three other modules I ordered, alas. Two of them I couldn’t get a peep out of, the other didn’t support English text-to-speech.

    SYN6658

    This one looks remarkably like the SYN6988:

    Yes, I added the 6658 label so I could tell the boards apart

    Apart from the main chip, the only difference appears to be that the board’s silkscreen says YS-V6 V1.15 where the SYN6988’s said YS-V6E V1.02.

    To be fair to YuTone (the manufacturer), they claim this only supports Chinese as an input language. If you feed it English, at best you’ll get it spelling out the letters. It does have quite a few amusing sounds, though, so at least you can make it beep and chime. My MicroPython library for the VoiceTX SYN6988 text to speech module can drive it as far as I understand it.

    Here are the sounds:

    NameTypeLink
    msgaPolyphonic Chord Beep
    msgbPolyphonic Chord Beep
    msgcPolyphonic Chord Beep
    msgdPolyphonic Chord Beep
    msgePolyphonic Chord Beep
    msgfPolyphonic Chord Beep
    msggPolyphonic Chord Beep
    msghPolyphonic Chord Beep
    msgiPolyphonic Chord Beep
    msgjPolyphonic Chord Beep
    msgkPolyphonic Chord Beep
    msglPolyphonic Chord Beep
    msgmPolyphonic Chord Beep
    msgnPolyphonic Chord Beep
    sound101Prompt Tone
    sound102Prompt Tone
    sound103Prompt Tone
    sound104Prompt Tone
    sound105Prompt Tone
    sound106Prompt Tone
    sound107Prompt Tone
    sound108Prompt Tone
    sound109Prompt Tone
    sound110Prompt Tone
    sound111Prompt Tone
    sound112Prompt Tone
    sound113Prompt Tone
    sound114Prompt Tone
    sound115Prompt Tone
    sound116Prompt Tone
    sound117Prompt Tone
    sound118Prompt Tone
    sound119Prompt Tone
    sound120Prompt Tone
    sound121Prompt Tone
    sound122Prompt Tone
    sound123Prompt Tone
    sound124Prompt Tone
    sound201phone ringtone
    sound202phone ringtone
    sound203phone ringtone
    sound204phone ringing
    sound205phone ringtone
    sound206door bell
    sound207door bell
    sound208doorbell
    sound209door bell
    sound210alarm
    sound211alarm
    sound212alarm
    sound213alarm
    sound214wind chimes
    sound215wind chimes
    sound216wind chimes
    sound217wind chimes
    sound218wind chimes
    sound219wind chimes
    sound301alarm
    sound302alarm
    sound303alarm
    sound304alarm
    sound305alarm
    sound306alarm
    sound307alarm
    sound308alarm
    sound309alarm
    sound310alarm
    sound311alarm
    sound312alarm
    sound313alarm
    sound314alarm
    sound315alert-emergency
    sound316alert-emergency
    sound317alert-emergency
    sound318alert-emergency
    sound319alert-emergency
    sound401credit card successful
    sound402credit card successful
    sound403credit card successful
    sound404credit card successful
    sound405credit card successful
    sound406credit card successful
    sound407credit card successful
    sound408successfully swiped the card
    sound501cuckoo
    sound502error
    sound503applause
    sound504laser
    sound505laser
    sound506landing
    sound507gunshot
    sound601alarm sound / air raid siren (long)
    sound602prelude to weather forecast (long)
    SYN-6658 Sound Reference

    Where I bought it: Electronic Component Module Store : Chinese-to-real-life Speech Synthesis Playing Module TTS Announcer SYN6658 of Bank Bus Broadcasting.

    Auto-translated manual:

    Unknown “TTS Text-to-speech Broadcast Synthesis Module”

    All I could get from this one was a power-on chime. The main chip has had its markings ground off, so I’ve no idea what it is.

    Red and black wires seem to be standard 5 V power. Yellow seems to be serial in, white is not connected.

    Where I bought it: Electronic Component Module Store / Chinese TTS Text-to-speech Broadcast Synthesis Module MCU Serial Port Robot Plays Prompt Advertising Board

    HLK-V40 Speech Synthesis Module

    In theory, this little board has a lot going for it: wifi, bluetooth, commands sent by AT commands. In practice, I couldn’t get it to do a thing.

    Where I bought it: HI-LINK Component Store / HLK-V40 Speech Synthesis Module TTS Pure Text to Speech Playback Hailinco AI intelligent Speech Synthesis Broadcast

    I’ve still got a SYN6288 to look at, plus a XFS5152CE TTS that’s in the mail that may or may not be in the mail. The SYN6988 is the best of the bunch so far.

  • SYN-6988 Speech with MicroPython

    Full repo, with module and instructions, here: scruss/micropython-SYN6988: MicroPython library for the VoiceTX SYN6988 text to speech module

    (and for those that CircuitPython is the sort of thing they like, there’s this: scruss/circuitpython-SYN6988: CircuitPython library for the YuTone VoiceTX SYN6988 text to speech module.)

    I have a bunch of other boards on order to see if the other chips (SYN6288, SYN6658, XF5152) work in the same way. I really wonder which I’ll end up receiving!

    Update (2023-07-09): Got the SYN6658. It does not support English TTS and thus is not recommended. It does have some cool sounds, though.

    Embedded Text Command Sound Table

    The github repo references Embedded text commands, but all of the sound references were too difficult to paste into a table there. So here are all of the ones that the SYN-6988 knows about:

    • Name is the string you use to play the sound, eg: [x1]sound101
    • Alias is an alternative name by which you can call some of the sounds. This is for better compatibility with the SYN6288 apparently. So [x1]sound101 is exactly the same as specifying [x1]sounda
    • Type is the sound description from the manual. Many of these are blank
    • Link is a playable link for a recording of the sound.
    NameAliasTypeLink
    sound101sounda
    sound102soundb
    sound103soundc
    sound104soundd
    sound105sounde
    sound106soundf
    sound107soundg
    sound108soundh
    sound109soundi
    sound110soundj
    sound111soundk
    sound112soundl
    sound113soundm
    sound114soundn
    sound115soundo
    sound116soundp
    sound117soundq
    sound118soundr
    sound119soundt
    sound120soundu
    sound121soundv
    sound122soundw
    sound123soundx
    sound124soundy
    sound201phone ringtone
    sound202phone ringtone
    sound203phone ringtone
    sound204phone rings
    sound205phone ringtone
    sound206doorbell
    sound207doorbell
    sound208doorbell
    sound209doorbell
    sound301alarm
    sound302alarm
    sound303alarm
    sound304alarm
    sound305alarm
    sound306alarm
    sound307alarm
    sound308alarm
    sound309alarm
    sound310alarm
    sound311alarm
    sound312alarm
    sound313alarm
    sound314alarm
    sound315alert/emergency
    sound316alert/emergency
    sound317alert/emergency
    sound318alert/emergency
    sound401credit card successful
    sound402credit card successful
    sound403credit card successful
    sound404credit card successful
    sound405credit card successful
    sound406credit card successful
    sound407credit card successful
    sound408successfully swiped the card
    SYN-6988 Sound Reference

  • Speech from Python with the SYN6988 module

    I’ve had one of these cheap(ish – $15) sound modules from AliExpress for a while. I hadn’t managed to get much out of it before, but I poked about at it a little more and found I was trying to drive the wrong chip. Aha! Makes all the difference.

    So here’s a short narration from my favourite Richard Brautigan poem, read by the SYN6988.

    Sensitive listener alert! There is a static click midway through. I edited out the clipped part, but it’s still a little jarring. It would always do this at the same point in playback, for some reason.

    The only Pythonish code I could find for these chips was meant for the older SYN6288 and MicroPython (syn6288.py). I have no idea what I’m doing, but with some trivial modification, it makes sound.

    I used the simple serial UART connection: RX -> TX, TX -> RX, 3V3 to 3V3 and GND to GND. My board is hard-coded to run at 9600 baud. I used the USB serial adapter that came with the board.

    Here’s the code that read that text:

    #!/usr/bin/env python3
    # -*- coding: utf-8 -*-
    
    import serial
    import time
    
    # NB via MicroPython and old too! Also for a SYN6288, which I don't have
    # nabbed from https://github.com/TPYBoard/TPYBoard_lib/
    
    def sendspeak(port, data):
        eec = 0
        buf = [0xFD, 0x00, 0, 0x01, 0x01]
        buf[2] = len(data) + 3
        buf += list(bytearray(data, encoding='utf-8'))
        for i in range(len(buf)):
            eec ^= int(buf[i])
        buf.append(eec)
        port.write(bytearray(buf))
    
    ser = serial.Serial("/dev/ttyUSB1", 9600)
    sendspeak(ser, "[t5]I like to think [p100](it [t7]has[t5] to be!)[p100] of a cybernetic ecology [p100]where we are free of our labors and joined back to nature, [p100]returned to our mammal brothers and sisters, [p100]and all watched over by machines of loving grace")
    time.sleep(8)
    ser.close()
    

    This code is bad. All I did was prod stuff until it stopped not working. Since all I have to work from includes a datasheet in Chinese (from here: ??????-SYN6988???TTS????) there’s lots of stuff I could do better. I used the tone and pause tags to give the reading a little more life, but it’s still a bit flat. For $15, though, a board that makes a fair stab at reading English is not bad at all. We can’t all afford vintage DECtalk hardware.

    The one thing I didn’t do is used the SYN6988’s Busy/Ready line to see if it was still busy reading. That means I could send it text as soon as it was ready, rather than pausing for 8 seconds after the speech. This refinement will come later, most likely when I port this to MicroPython.

    More resources:

  • A terrible guide to singing with DECtalk

    It’s now possible to build and run the DECtalk text to speech system on Linux. It even builds under emscripten, enabling DECtalk for Web in your browser. You too can annoy everyone within earshot making it prattle on about John Madden.

    But DECTalk can sing! Because it’s been around so long, there are huge archives of songs in DECtalk format out there. The largest archive is at THE FLAME OF HOPE website, under the Dectalk section.

    Building DECtalk songs isn’t easy, especially for a musical numpty like me. You need a decent grasp of music notation, phonemic/phonetic markup and patience with DECtalk’s weird and ancient text formats.

    DECtalk phonemes

    While DECtalk can accept text and turn it into a fair approximation of spoken English, for singing you have to use phonemes. Let’s say we have a solfège-ish major scale:

    do re mi fa sol la ti do

    If we’re all fancy-like and know our International Phonetic Alphabet (IPA), that would translate to:

    /doʊ ɹeɪ miː faː soʊ laː tiː doʊ/

    or if your fonts aren’t up to IPA:

    /doʊ ɹeɪ miː faː soʊ laː tiː doʊ/
(maybe)

/do? ?e? mi? f?? so? l?? ti? do?/

(sorry about this, my website hates Unicode still)

    DECtalk uses a variant on the ARPABET convention to represent IPA symbols as ASCII text. The initial consonant sounds remain as you might expect: D, R, M, F, S, L and T. The vowel sounds, however, are much more complex. This will give us a DECtalk-speakable phrase:

    [dow rey miy faa sow laa tiy dow].

    Note the opening and closing brackets and the full stop at the end. The brackets introduce phonemes, and the full stop tells DECtalk that the text is at an end. Play it in the DECtalk for Web window and be unimpressed: while the pitch changes are non-existent, the sounds are about right.

    For more information about DECtalk phonemes, please see Phonemic Symbols Listed By Language and chapter 7 of DECtalk DTC03 Text-to-Speech System Owner’s Manual.

    If you want to have a rough idea of what the phonemes in a phrase might be, you can use DECtalk’s :log phonemes option. You might still have to massage the input and output a bit, like using sed to remove language codes:

    say -l us -pre '[:log phonemes on]' -post '[:log phonemes off]' -a "doe ray me fah so lah tea doe" | sed 's/us_//g;'
    d ' ow  r ' ey  m iy  f ' aa) s ow  ll' aa  t ' iy  d ' ow.

    Music notation

    To me — a not very musical person — staff notation looks like it was designed by a maniac. A more impractical system to indicate arrangement of notes and their durations I don’t think I could come up with: and yet we’re stuck with it.

    DECtalk uses a series of numbered pitches plus durations in milliseconds for its singing mode. The notes (1–37) correspond to C2 to C5. If you’re familiar with MIDI note numbers, DECtalk’s 1–37 correspond to MIDI note numbers 36–72. This is how DECtalk’s pitch numbers would look as major scales on the treble clef:

    a treble clef showing quarter notes from C2 to C5 in the scale of C Major
    The entire singing range of DECtalk as a C Major scale, from note 1 (C2, 65.4 Hz) to note 37 (C5, 523.4 Hz)

    I’m not sure browsers can play MIDI any more, but here you go (doremi-abc.mid):

    and since I had to learn abc notation to make these noises, here is the source:

    %abc-2.1
    X:1
    T:Do Re Mi
    C:Trad.
    M:4/4
    L:1/4
    Q:1/4=120
    K:C
    %1
    C,, D,, E,, F,,| G,, A,, B,, C,| D, E, F, G,| A, B, C D| E F G A| B c z2 |]
    w:do re mi fa sol la ti do re mi fa sol la ti do re mi fa sol la ti do

    Each element of a DECtalk song takes the following form:

    phoneme <duration, pitch number>

    The older DTC-03 manual hints that it takes around 100 ms for DECtalk to hit pitch, so for each ½ second utterance (or quarter note at 120 bpm, ish), I split it up as:

    • 100 ms of the initial consonant;
    • 337 ms of the vowel sound;
    • 63 ms of pause (which has the phoneme code “_”). Pauses don’t need pitch numbers, unless you want them to preempt DECtalk’s pitch-change algorithm.

    So the three lowest notes in the major scale would sing as:

    [d<100,1>ow<337,1>_<63>
     r<100,3>ey<337,3>_<63>
     m<100,5>iy<337,5>_<63>].

    I’ve split them into line for ease of reading, but DECtalk adds extra pauses if you include spaces, so don’t.

    The full three octave major scale looks like this:

    [d<100,1>ow<337,1>_<63>r<100,3>ey<337,3>_<63>m<100,5>iy<337,5>_<63>f<100,6>aa<337,6>_<63>s<100,8>ow<337,8>_<63>l<100,10>aa<337,10>_<63>t<100,12>iy<337,12>_<63>d<100,13>ow<337,13>_<63>r<100,15>ey<337,15>_<63>m<100,17>iy<337,17>_<63>f<100,18>aa<337,18>_<63>s<100,20>ow<337,20>_<63>l<100,22>aa<337,22>_<63>t<100,24>iy<337,24>_<63>d<100,25>ow<337,25>_<63>r<100,27>ey<337,27>_<63>m<100,29>iy<337,29>_<63>f<100,30>aa<337,30>_<63>s<100,32>ow<337,32>_<63>l<100,34>aa<337,34>_<63>t<100,36>iy<337,36>_<63>d<100,37>ow<337,37>_<63>].

    You can paste that into the DECtalk browser window, or run the following from the command line on Linux:

    say -pre '[:PHONE ON]' -a '[d<100,1>ow<337,1>_<63>r<100,3>ey<337,3>_<63>m<100,5>iy<337,5>_<63>f<100,6>aa<337,6>_<63>s<100,8>ow<337,8>_<63>l<100,10>aa<337,10>_<63>t<100,12>iy<337,12>_<63>d<100,13>ow<337,13>_<63>r<100,15>ey<337,15>_<63>m<100,17>iy<337,17>_<63>f<100,18>aa<337,18>_<63>s<100,20>ow<337,20>_<63>l<100,22>aa<337,22>_<63>t<100,24>iy<337,24>_<63>d<100,25>ow<337,25>_<63>r<100,27>ey<337,27>_<63>m<100,29>iy<337,29>_<63>f<100,30>aa<337,30>_<63>s<100,32>ow<337,32>_<63>l<100,34>aa<337,34>_<63>t<100,36>iy<337,36>_<63>d<100,37>ow<337,37>_<63>].'

    It sounds like this:

    Singing a scale is hardly singing a tune, but hey, you were warned that this was a terrible guide at the outset. I hope I’ve given you a start on which you can build your own songs.

    (One detail I haven’t tried yet: the older DTC-03 manual hints that singing notes can take Hz values instead of pitch numbers, and apparently loses the vibrato effect. It’s not that hard to convert from a note/octave to a frequency. Whether this still works, I don’t know.)

    This post from Patrick Perdue suggested to me I had to dig into the Hz value substitution because the results are so gloriously awful. Of course, I had to write a Perl regex to make the conversions from DECtalk 1–37 sung notes to frequencies from 65–523 Hz:

    perl -pwle 's|(?<=,)(\d+)(?=>)|sprintf("%.0f", 440*2**(($1-34)/12))|eg;'

    (as one does). So the sung scale ends up as this non-vibrato text:

    say -pre '[:PHONE ON]' -a '[d<100,65>ow<337,65>_<63>r<100,73>ey<337,73>_<63>m<100,82>iy<337,82>_<63>f<100,87>aa<337,87>_<63>s<100,98>ow<337,98>_<63>l<100,110>aa<337,110>_<63>t<100,123>iy<337,123>_<63>d<100,131>ow<337,131>_<63>r<100,147>ey<337,147>_<63>m<100,165>iy<337,165>_<63>f<100,175>aa<337,175>_<63>s<100,196>ow<337,196>_<63>l<100,220>aa<337,220>_<63>t<100,247>iy<337,247>_<63>d<100,262>ow<337,262>_<63>r<100,294>ey<337,294>_<63>m<100,330>iy<337,330>_<63>f<100,349>aa<337,349>_<63>s<100,392>ow<337,392>_<63>l<100,440>aa<337,440>_<63>t<100,494>iy<337,494>_<63>d<100,523>ow<337,523>_<63>].'
    

    That doesn’t sound as wondrously terrible as it should, most probably as they are very small differences between each sung word. So how about we try something better? Like the refrain from The Turtles’ Happy Together, as posted on TheFlameOfHope:

    say -pre '[:PHONE ON]' -a '[:nv] [:dv gn 73] [AY<400,29> KAE<200,24> N<100> T<100> SIY<400,21> MIY<400,17> LAH<200,15> VAH<125,19> N<75> NOW<400,22> BAH<200,26> DXIY<200,27> BAH<300,26> T<100> YU<600,24> FOR<200,21> AO<300,24> LX<100> MAY<400,26> LAY<900,27> F<300> _<400> WEH<300,29> N<100> YXOR<400,24> NIR<400,21> MIY<400,17> BEY<200,15> BIY<200,19> DHAX<400,22> SKAY<125,26> Z<75> WIH<125,27> LX<75> BIY<400,26> BLUW<600,24> FOR<200,21> AO<300,24> LX<100> MAY<400,26> LAY<900,27> F<300> _<300> ].'

    “Refrain” is a good word, as it’s exactly what I should have done, rather than commit a terribleness on the audio by de-vibratoing it:

    say -pre '[:PHONE ON]' -a '[:nv] [:dv gn 73] [AY<400,330> KAE<200,247> N<100> T<100> SIY<400,208> MIY<400,165> LAH<200,147> VAH<125,185> N<75> NOW<400,220> BAH<200,277> DXIY<200,294> BAH<300,277> T<100> YU<600,247> FOR<200,208> AO<300,247> LX<100> MAY<400,277> LAY<900,294> F<300> _<400> WEH<300,330> N<100> YXOR<400,247> NIR<400,208> MIY<400,165> BEY<200,147> BIY<200,185> DHAX<400,220> SKAY<125,277> Z<75> WIH<125,294> LX<75> BIY<400,277> BLUW<600,247> FOR<200,208> AO<300,247> LX<100> MAY<400,277> LAY<900,294> F<300> _<300> ].'

    Oh dear. You can’t unhear that, can you?

  • Using the IBM Wheelwriter 10 Series II Typewriter as a printer

    I can’t believe I’m having to write this article again. Back in 2004, I picked up an identical model of typewriter on Freecycle, also complete with the parallel printer option board. The one I had back then had an incredible selection of printwheels. And I gave it all away! Aaargh! Why?

    Last month, I ventured out to a Value Village in more affluent part of town. On the shelf for $21 was a familiar boxy shape, another Wheelwriter 10 Series II Typewriter model 6783. This one also has the printer option board, but it only has one printwheel, Prestige Elite. It powered on enough at the test rack enough for me to see it mostly worked, so I bought it.

    Once I got it home, though, I could see it needed some work. The platen was covered in ink and correction fluid splatters. Worse, the carriage would jam in random places. It was full of dust and paperclips. But the printwheel did make crisp marks on paper, so it was worth looking at a repair.

    Thanks to Phoenix Typewriter’s repair video “IBM Wheelwriter Typewriter Repair Fix Carriage Carrier Sticks Margins Reset Makes Noise”, I got it going again. I’m not sure how much life I’ve got left in the film ribbon, but for now it’s doing great.

    Note that there are lots of electronics projects — such as tofergregg/IBM-Wheelwriter-Hack: Turning an IBM Wheelwriter into a unique printer — that use an Arduino or similar to drive the printer. This is not that (or those). Here I’m using the Printer Option board plus a USB to Parallel cable. There’s almost nothing out there about how these work.

    Connecting the printer

    You’ll need a USB to Parallel adapter, something like this: StarTech 10 ft USB to Parallel Printer Adapter – M/M. You need the kind with the big Centronics connector, not the 25-pin D-type. My one (old) has a chunky plastic case that won’t fit into the port on the Wheelwriter unless you remove part of the cable housing. On my Linux box, the port device is /dev/usb/lp0. You might want to add yourself to the lp group so you can send data to the printer without using sudo:

    sudo adduser user lp

    The Wheelwriter needs to be switched into printer mode manually by pressing the Code + Printer Enable keys.

    Printer Codes

    As far as I can tell, the Wheelwriter understands a subset of IBM ProPrinter codes. Like most simple printers, most control codes start with an Esc character (ASCII 27). Lines need to end with both a Carriage Return (ASCII 13) and newline (ASCII 10). Sending only CRs allows overprinting, while sending only newlines gives stair-step output.

    The codes I’ve found to work so far are:

    • Emphasized printingEsc E
    • Cancel emphasized printingEsc F
      (double strike printing [Esc G, Esc H] might also work, but I haven’t tried them)
    • Continuous underscoreEsc – 1
    • Cancel continuous underscoreEsc – 0
      (technically, these are Escn, where n = ASCII 1 or 0, not character “1” or “0”. But the characters seem to work, too)
    • 7/72″ inch line spacingEsc 1
    • Set text line spacing to n / 72″ unitsEsc A n
      (this one really matters: if you send “6” (ASCII 66) instead of 6, you’ll get 66/72 = 11/12″ [= 28.3 mm] line spacing instead of the 1/12″ [= 2.1 mm] you expected)
    • Start text line spacingEsc 2

    Text functions such as italics and extended text aren’t possible with a daisywheel printer. You can attempt dot-matrix graphics using full stops and micro spacing, but I don’t want to know you if you’d try.

    Sending codes from the command line

    echo is about the simplest way of doing it. Some systems provide an echo built-in that doesn’t support the -e (interpret special characters) and -n (don’t send newline) options. You may have to call /usr/bin/echo instead.

    To print emphasized:

    echo -en 'well \eEhello\eF there!\r\n' > /dev/usb/lp0

    which prints

    well hello there!

    To print underlined:

    echo -en 'well \e-1hello\e-0 there!\r\n' > /dev/usb/lp0

    which types

    well hello there!

    To set the line spacing to a (very cramped) 1/12″ [= 2.1 mm] and print a horizontal line of dots and a vertical line of dots, both equally spaced (if you’re using Prestige Elite):

    echo -en '\eA\x05\e2\r\n..........\r\n.\r\n.\r\n.\r\n.\r\n.\r\n.\r\n.\r\n.\r\n.\r\n\r\n' > /dev/usb/lp0

    Character set issues

    IBM daisywheels typically can’t represent the whole ASCII character set. Here’s what an attempt to print codes 33 to 126 in Prestige Elite looks like:

    tabulation of printable ASCII characters on orange background. Some characters are clearly missing

    The following characters are missing:

    < > \ ^ ` { | } ~

    So printing your HTML or Python is right out. FORTRAN, as ever, is safe.

    Prestige Elite is a 12 character per inch font (“12 pitch”, or even “Elite” in typewriter parlance) that’s mostly been overshadowed by Courier (typically 10 characters per inch) in computer usage. This is a shame, as it’s a much prettier font.

    Related, yet misc.

    There’s very little out there about printing with IBM daisywheels. This is a dump of the stuff I’ve found that may help other people:

    • Wheelwriter 10 Series II Typewriter 6783 Operator’s Guide (Internet Archive; nothing about the printer option)
    • IBM didn’t make too many daisywheel printers. Two models were the 5216 Wheelprinter and 5223 Wheelprinter E, possibly intended for larger IBM machines. The 5216 Wheelprinter looks like it may use similar character codes. Here’s a (Printer Definition File?? An IBM thing, I think) for that printer that might help the interested: ibm5216_pdf
    • The IBM 6901 “Personal Typing System” included a daisywheel printer (Correcting Wheelwriter Printer 6902) that looks almost identical to a Wheelwriter 10 Series II with the keyboard lopped off. But I can find nothing about it.
    • Word Perfect 5 may have had a driver for this typewriter/printer, but that doesn’t help me with the control codes.
  • The Joy of BirdNetPi

    I don’t think I’ve had as much enjoyment for a piece of software for a very long time as I’ve had with BirdNET-Pi. It’s a realtime acoustic bird classification system for the Raspberry Pi. It listens through a microphone you place somewhere near where you can hear birds, and it’ll go off and guess what it’s hearing, using a cut-down version of the BirdNET Sound ID model. It does this 24/7, and saves the samples it hears. You can then go to a web page (running on the same Raspberry Pi) and look up all the species it has heard.

    Our Garden

    a somewhat overgrown garden with budding green trees against blue sky

    Not very impressive, kind of overgrown, in the wrong part of town. Small, too. But birds love it. At this time of year, it’s alive with birds. You can’t make them out, but there’s a pair of Rose-breasted Grosbeaks happily snacking near the top of the big tree. There are conifers next door too, so we get birds we wouldn’t expect.

    We are next to two busy subway/train stations, and in between two schools. There’s a busy intersection nearby, too. Consequently, the background noise is horrendous

    What I used

    This was literally “stuff I had lying around”:

    • Raspberry Pi 3B+ (with power supply, case, thermostatic fan and SD card)
    • USB extension cable (this, apparently, is quite important to isolate the USB audio device from electrical noise)
    • Horrible cheap USB sound card: I paid about $2 for a “3d sound” thing about a decade ago. It records in mono. It works. My one is wrapped in electrical tape as the case keeps threatening to fall off, plus it has a hugely bright flashing LED the is annoying.
    • Desktop mic (circa 2002): before video became a thing, PCs had conferencing microphones. I think I got this one free with a PC over 20 years ago. It’s entirely unremarkable and is not an audiophile device. I stuck it out a back window and used a strip of gaffer tape to stop bugs getting in. It’s not waterproof, but it didn’t rain the whole week it was out the window.
    • Raspberry Pi OS Lite 64-bit. Yes, it has to be 64 bit.
    • BirdNET-Pi installation on top.

    I spent very little time optimizing this. I had to fiddle with microphone gain slightly. That’s all.

    What I heard

    To the best of my knowledge, I have actual observations of 30 species, observed between May 7th and May 16th 2023:

    American Goldfinch, American Robin, Baltimore Oriole, Blue Jay, Cedar Waxwing, Chimney Swift, Clay-colored Sparrow, Common Grackle, Common Raven, Gray Catbird, Hermit Thrush, House Finch, House Sparrow, Killdeer, Mourning Dove, Nashville Warbler, Northern Cardinal, Northern Parula, Orchard Oriole, Ovenbird, Red-winged Blackbird, Ring-billed Gull, Rose-breasted Grosbeak, Ruby-crowned Kinglet, Song Sparrow, Veery, Warbling Vireo, White-throated Sparrow, White-winged Crossbill, Wood Thrush

    I’ll put the recordings at the end of this post. Note, though, they’re noisy: Cornell Lab quality they ain’t.

    What I learned

    This is the first time that I’ve let an “AI” classifier model run with no intervention. If it flags some false positives, then it’s pretty low-stakes when it’s wrong. And how wrong did it get some things!

    allegedly a Barred Owl, this is clearly a two-stroke leafblower
    Black-Billed Cuckoo? How about kids playing in the school yard?
    Emergency vehicles are Common Loons now, according to BirdNetPi
    Police cars at 2:24 am are Eastern Screech-Owls. I wonder if we could use this classifier to detect over-policed, under-served neighbourhoods?
    Great Black-backed Gulls, or kids playing? The latter
    Turkey Vulture? How about a very farty two-stroke engine in a bicycle frame driving past?
    (This thing stinks out the street, blecch)

    There are also false positive for Trumpeter Swans (local dog) and Tundra Swans (kids playing). These samples had recognizable voices, so I didn’t include them here.

    The 30 positive species identifications

    Many of these have a fairly loud click at the start of the sample, so mind your ears.

    American Goldfinch

    American Robin

    Baltimore Oriole

    (I dunno what’s going on here; the next sample’s much more representative)

    Blue Jay

    Cedar Waxwing

    Chimney Swift

    Clay-colored Sparrow

    Common Grackle

    Common Raven

    Gray Catbird

    Hermit Thrush

    House Finch

    House Sparrow

    Killdeer

    Mourning Dove

    Nashville Warbler

    Northern Cardinal

    Hey, we’ve got both of the repetitive songs that these little doozers chirp out all day. Song 1:

    and song 2 …

    Northern Parula

    Orchard Oriole

    Ovenbird

    Red-winged Blackbird

    Ring-billed Gull

    Rose-breasted Grosbeak

    Ruby-crowned Kinglet

    Song Sparrow

    Veery

    Warbling Vireo

    White-throated Sparrow

    White-winged Crossbill

    Wood Thrush

    Boring technical bit

    BirdNetPi doesn’t create combined spectrograms with audio as a single video file. What it does do is create an mp3 plus a PNG of the spectrogram. ffmpeg can make a nice not-too-large webm video for sharing:

    ffmpeg -loop 1 -y -i 'birb.mp3.png' -i 'birb.mp3' -ac 1 -crf 48 -vf scale=720:-2 -shortest 'birb.webm'

    (Minor update, May 2024: the original project maintainer has moved on, so I changed the project link to point to Nachtzuster/BirdNET-Pi: A realtime acoustic bird classification system for the Raspberry Pi 5, 4B 3B+ 0W2 and more. Built on the TFLite version of BirdNET.)

  • Edwin Morgan’s “The Computer’s First Christmas Card”

    as performed by the flite speech synthesizer and some shell scripts

    The Computer’s First Christmas card

    Not quite as good as having the late Prof. Morgan recite it to you himself — one of the few high points of my school experience — but you take what you can get in this economy.

     MERRY CHRISTMAS
    *** FORTRAN STOP
  • MicroPython on the Seeed Studio Wio Terminal: it works!

    A while back, Seeed Studio sent me one of their Wio Terminal devices to review. It was pretty neat, but being limited to using Arduino to access all of it features was a little limiting. I still liked it, though, and wrote about it here: SeeedStudio Wio Terminal

    Small screen device showing geometric pattern
    Wio Terminal, doing a thing

    There wasn’t any proper MicroPython support for the device as it used a MicroChip/Atmel SAMD51 ARM® Cortex®-M4 micro-controller. But since I wrote the review, one developer (robert-hh) has worked almost entirely solo to make SAMD51 and SAMD21 support useful in mainline MicroPython.

    Hey! Development is still somewhere between “not quite ready for prime time” and “beware of the leopard”. MicroPython on the SAMD51 works remarkably well for supported boards, but don’t expect this to be beginner-friendly yet.

    I thought I’d revisit the Wio Terminal and see what I could do using a nightly build (downloaded from Downloads – Wio Terminal D51R – MicroPython). Turns out, most of the board works really well!

    What doesn’t work yet

    • Networking/Bluetooth – this is never going to be easy, especially with Seeed Studio using a separate RTL8720 SoC. It may not be entirely impossible, as previously thought, but so far, wifi support seems quite far away
    • QSPI flash for program storagethis is not impossible, just not implemented yet this works now too, but it’s quite slow since it relies on a software SPI driver. More details: samd51: MicroPython on the Seeed Wio Terminal · Discussion #9838 · micropython
    • RTCthis is a compile-time option, but isn’t available on the stock images. Not all SAMD51 boards have a separate RTC oscillator, and deriving the RTC from the system oscillator would be quite wobbly. RTC works now! It may even be possible to provide backup battery power and have it keep time when powered off. VBAT / PB03 / SPI_SCK is broken out to the 40-pin connector.

    What does work

    • Display – ILI9341 320×240 px, RGB565 via SPI
    • Accelerometer – LIS3DHTR via I²C
    • Microphone – analogue
    • Speaker – more like a buzzer, but this little PWM speaker element does allow you to play sounds
    • Light Sensor – via analogue photo diode
    • IR emitter – PWM, not tied to any hardware protocol
    • Internal LED – a rather faint blue thing, but useful for low-key signalling
    • Micro SD Card – vi SPI. Works well with MicroPython’s built-in virtual file systems
    • Switches and buttons – three buttons on the top, and a five-way mini-joystick
    • I²C via Grove Connector – a second, separate I²C channel.

    I’ll go through each of these here, complete with a small working example.

    Wio Terminal main board
    Inside the remarkably hard-to-open Wio Terminal

    LED

    Let’s start with the simplest feature: the tiny blue LED hidden inside the case. You can barely see this, but it glows out around the USB C connector on the bottom of the case.

    • MicroPython interfaces: machine.Pin, machine.PWM
    • Control pin: Pin(“LED_BLUE”) or Pin(15), or Pin(“PA15”): any one of these would work.

    Example: Wio-Terminal-LED.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-LED.py - blink the internal blue LED
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    from machine import Pin
    from time import sleep_ms
    
    led = Pin("LED_BLUE", Pin.OUT)  # or Pin(15) or Pin("PA15")
    
    try:
        while True:
            led.value(not led.value())
            sleep_ms(1200)
    except:
        led.value(0)  # turn it off if user quits
        exit()
    

    IR LED

    I don’t have any useful applications of the IR LED for device control, so check out Awesome MicroPython’s IR section for a library that would work for you.

    • MicroPython interfaces: machine.PWM
    • Control pin: Pin(“PB31”)

    Example: Wio-Terminal-IR_LED.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-IR_LED.py - blink the internal IR LED
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    # Hey! This is a completely futile exercise, unless you're able
    # to see into the IR spectrum. But we're here to show you the pin
    # specification to use. For actual useful libraries to do stuff with
    # IR, take a look on https://awesome-micropython.com/#ir
    
    # So this is a boring blink, 'cos we're keeping it short here.
    # You might be able to see the LED (faintly) with your phone camera
    
    from machine import Pin, PWM
    from time import sleep_ms
    
    ir = PWM(Pin("PB31"))  # "IR_CTL" not currently defined
    
    try:
        while True:
            ir.duty_u16(32767)  # 50% duty
            ir.freq(38000)  # fast flicker
            sleep_ms(1200)
            ir.duty_u16(0)  # off
            sleep_ms(1200)
    except:
        ir.duty_u16(0)  # turn it off if user quits
        exit()
    

    Buttons

    There are three buttons on top, plus a 5-way joystick on the front. Their logic is inverted, so they read 0 when pressed, 1 when not. It’s probably best to use machine.Signal with these to make operation more, well, logical.

    • MicroPython interface: machine.Signal (or machine.Pin)
    • Control pins: Pin(“BUTTON_3”) or Pin(92) or Pin(PC28) – top left; Pin(“BUTTON_2”) or Pin(91) or Pin(PC27) – top middle; Pin(“BUTTON_1”) or Pin(90) or Pin(PC26) – top right; Pin(“SWITCH_B”) or Pin(108) or Pin(PD12) – joystick left; Pin(“SWITCH_Y”) or Pin(105) or Pin(PD09) – joystick right; Pin(“SWITCH_U”) or Pin(116) or Pin(PD20) – joystick up; Pin(“SWITCH_X”) or Pin(104) or Pin(PD08) – joystick down; Pin(“SWITCH_Z”) or Pin(106) or Pin(PD10) – joystick button

    Example: Wio-Terminal-Buttons.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-Buttons.py - test the buttons
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    # using Signal because button sense is inverted: 1 = off, 0 = on
    from machine import Pin, Signal
    from time import sleep_ms
    
    pin_names = [
        "BUTTON_3",  # Pin(92)  or Pin(PC28) - top left
        "BUTTON_2",  # Pin(91)  or Pin(PC27) - top middle
        "BUTTON_1",  # Pin(90)  or Pin(PC26) - top right
        "SWITCH_B",  # Pin(108) or Pin(PD12) - joystick left
        "SWITCH_Y",  # Pin(105) or Pin(PD09) - joystick right
        "SWITCH_U",  # Pin(116) or Pin(PD20) - joystick up
        "SWITCH_X",  # Pin(104) or Pin(PD08) - joystick down
        "SWITCH_Z",  # Pin(106) or Pin(PD10) - joystick button
    ]
    
    pins = [None] * len(pin_names)
    for i, name in enumerate(pin_names):
        pins[i] = Signal(Pin(name, Pin.IN), invert=True)
    
    while True:
        for i in range(len(pin_names)):
            print(pins[i].value(), end="")
        print()
        sleep_ms(100)
    

    Buzzer

    A very quiet little PWM speaker.

    • MicroPython interfaces: machine.PWM
    • Control pin: Pin(“BUZZER”) or Pin(107) or Pin(“PD11”)

    Example: Wio-Terminal-Buzzer.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-Buzzer.py - play a scale on the buzzer with PWM
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    from time import sleep_ms
    from machine import Pin, PWM
    
    pwm = PWM(Pin("BUZZER", Pin.OUT))  # or Pin(107) or Pin("PD11")
    cmaj = [262, 294, 330, 349, 392, 440, 494, 523]  # C Major Scale frequencies
    
    for note in cmaj:
        print(note, "Hz")
        pwm.duty_u16(32767)  # 50% duty
        pwm.freq(note)
        sleep_ms(225)
        pwm.duty_u16(0)  # 0% duty - silent
        sleep_ms(25)
    

    Light Sensor

    This is a simple photo diode. It doesn’t seem to return any kind of calibrated value. Reads through the back of the case.

    • MicroPython interfaces: machine.ADC
    • Control pin: machine.ADC(“PD01”)

    Example code: Wio-Terminal-LightSensor.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-LightSensor.py - print values from the light sensor
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    from time import sleep_ms
    from machine import ADC
    
    # PD15-22C/TR8 photodiode
    light_sensor = ADC("PD01")
    
    while True:
        print([light_sensor.read_u16()])
        sleep_ms(50)
    

    Microphone

    Again, a simple analogue sensor:

    • MicroPython interfaces: machine.ADC
    • Control pin: machine.ADC(“MIC”)

    Example: Wio-Terminal-Microphone.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-Microphone.py - print values from the microphone
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    from time import sleep_ms
    from machine import ADC
    
    mic = ADC("MIC")
    
    while True:
        print([mic.read_u16()])
        sleep_ms(5)
    

    Grove I²C Port

    The Wio Terminal has two Grove ports: the one on the left (under the speaker port) is an I²C port. As I don’t know what you’ll be plugging in there, this example does a simple bus scan. You could make a, appalling typewriter if you really wanted.

    • MicroPython interfaces: machine.I2C (channel 3), machine. Pin
    • Control pins: scl=Pin(“SCL1”), sda=Pin(“SDA1”)

    Example: Wio-Terminal-Grove-I2C.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-Grove-I2C.py - show how to connect on Grove I2C
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    from machine import Pin, I2C
    
    # NB: This doesn't do much of anything except list what's
    # connected to the left (I²C) Grove connector on the Wio Terminal
    
    i2c = I2C(3, scl=Pin("SCL1"), sda=Pin("SDA1"))
    devices = i2c.scan()
    
    if len(devices) == 0:
        print("No I²C devices connected to Grove port.")
    else:
        print("Found these I²C devices on the Grove port:")
        for n, id in enumerate(devices):
            print(" device", n, ": ID", id, "(hex:", hex(id) + ")")
    

    LIS3DH Accelerometer

    This is also an I²C device, but connected to a different port (both logically and physically) than the Grove one.

    • MicroPython interfaces: machine.I2C (channel 4), machine. Pin
    • Control pins: scl=Pin(“SCL0”), sda=Pin(“SDA0”)
    • Library: from MicroPython-LIS3DH, copy lis3dh.py to the Wio Terminal’s small file system. Better yet, compile it to mpy using mpy-cross to save even more space before you copy it across

    Example: Wio-Terminal-Accelerometer.py (based on tinypico-micropython/lis3dh library/example.py)

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-Accelerometer.py - test out accelerometer
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    # based on
    #  https://github.com/tinypico/tinypico-micropython/tree/master/lis3dh%20library
    
    import lis3dh, time, math
    from machine import Pin, I2C
    
    i2c = I2C(4, scl=Pin("SCL0"), sda=Pin("SDA0"))
    imu = lis3dh.LIS3DH_I2C(i2c)
    
    last_convert_time = 0
    convert_interval = 100  # ms
    pitch = 0
    roll = 0
    
    # Convert acceleration to Pitch and Roll
    def convert_accell_rotation(vec):
        x_Buff = vec[0]  # x
        y_Buff = vec[1]  # y
        z_Buff = vec[2]  # z
    
        global last_convert_time, convert_interval, roll, pitch
    
        # We only want to re-process the values every 100 ms
        if last_convert_time < time.ticks_ms():
            last_convert_time = time.ticks_ms() + convert_interval
    
            roll = math.atan2(y_Buff, z_Buff) * 57.3
            pitch = (
                math.atan2((-x_Buff), math.sqrt(y_Buff * y_Buff + z_Buff * z_Buff)) * 57.3
            )
    
        # Return the current values in roll and pitch
        return (roll, pitch)
    
    
    # If we have found the LIS3DH
    if imu.device_check():
        # Set range of accelerometer (can be RANGE_2_G, RANGE_4_G, RANGE_8_G or RANGE_16_G).
        imu.range = lis3dh.RANGE_2_G
    
        # Loop forever printing values
        while True:
            # Read accelerometer values (in m / s ^ 2).  Returns a 3-tuple of x, y,
            # z axis values.  Divide them by 9.806 to convert to Gs.
            x, y, z = [value / lis3dh.STANDARD_GRAVITY for value in imu.acceleration]
            print("x = %0.3f G, y = %0.3f G, z = %0.3f G" % (x, y, z))
    
            # Convert acceleration to Pitch and Roll and print values
            p, r = convert_accell_rotation(imu.acceleration)
            print("pitch = %0.2f, roll = %0.2f" % (p, r))
    
            # Small delay to keep things responsive but give time for interrupt processing.
            time.sleep(0.1)
    

    SD Card

    • MicroPython interfaces: machine.SPI (channel 6), machine.Pin, machine.Signal
    • Control Pins: Pin(“SD_SCK”), Pin(“SD_MOSI”), Pin(“SD_MISO”) for SD access. Pin(“SD_DET”) is low if an SD card is inserted, otherwise high
    • Library: copy sdcard.py from micropython-lib to the Wio Terminal’s file system.

    Rather than provide a small canned example (there’s one here, if you must: Wio-Terminal-SDCard.py) here’s my boot.py startup file, showing how I safely mount an SD card if there’s one inserted, but keep booting even if it’s missing:

    # boot.py - MicroPython / Seeed Wio Terminal / SAMD51
    
    import sys
    
    sys.path.append("/lib")
    
    import machine
    import gc
    import os
    import sdcard
    
    machine.freq(160000000)  # fast but slightly jittery clock
    gc.enable()
    
    # mount SD card if there's one inserted
    try:
        sd_detected = machine.Signal(
            machine.Pin("SD_DET", machine.Pin.IN),
            invert=True,
        )
        sd_spi = machine.SPI(
            6,
            sck=machine.Pin("SD_SCK"),
            mosi=machine.Pin("SD_MOSI"),
            miso=machine.Pin("SD_MISO"),
            baudrate=40000000,
        )
        sd = sdcard.SDCard(sd_spi, machine.Pin("SD_CS"))
        if sd_detected.value() == True:
            os.mount(sd, "/SD")
            print("SD card mounted on /SD")
        else:
            raise Exception("SD card not inserted, can't mount /SD")
    except:
        print("SD card not found")
    
    
    

    ILI9341 Display

    I’m going to use the library rdagger/micropython-ili9341: MicroPython ILI9341Display & XPT2046 Touch Screen Driver because it’s reliable, and since it’s written entirely in MicroPython, it’s easy to install. It’s not particularly fast, though.

    The Wio Terminal may have an XPT2046 resistive touch controller installed, but I haven’t been able to test it. There are LCD_XL, LCD_YU, LCD_XR and LCD_YD lines on the schematic that might indicate it’s there, though.

    • MicroPython interfaces: machine.SPI (channel 7), machine.Pin.
    • Control Pins: Pin(“LCD_SCK”), Pin(“LCD_MOSI”), Pin(“LCD_MISO”). Pin(“LED_LCD”) is the backlight control
    • Library: copy ili9341.py from rdagger /micropython-ili9341 to the Wio Terminal’s file system.

    This demo draws rainbow-coloured diamond shapes that change continuously.

    Example: Wio-Terminal-Screen.py

    # MicroPython / Seeed Wio Terminal / SAMD51
    # Wio-Terminal-Screen.py - output something on the ILI9341 screen
    # scruss, 2022-10
    # -*- coding: utf-8 -*-
    
    
    from time import sleep
    from ili9341 import Display, color565
    from machine import Pin, SPI
    
    
    def wheel565(pos):
        # Input a value 0 to 255 to get a colour value.
        # The colours are a transition r - g - b - back to r.
        # modified to return RGB565 value for ili9341 - scruss
        (r, g, b) = (0, 0, 0)
        if (pos < 0) or (pos > 255):
            (r, g, b) = (0, 0, 0)
        if pos < 85:
            (r, g, b) = (int(pos * 3), int(255 - (pos * 3)), 0)
        elif pos < 170:
            pos -= 85
            (r, g, b) = (int(255 - pos * 3), 0, int(pos * 3))
        else:
            pos -= 170
            (r, g, b) = (0, int(pos * 3), int(255 - pos * 3))
        return (r & 0xF8) << 8 | (g & 0xFC) << 3 | b >> 3
    
    
    # screen can be a little slow to turn on, so use built-in
    # LED to signal all is well
    led = Pin("LED_BLUE", Pin.OUT)
    
    backlight = Pin("LED_LCD", Pin.OUT)  # backlight is not a PWM pin
    spi = SPI(
        7, sck=Pin("LCD_SCK"), mosi=Pin("LCD_MOSI"), miso=Pin("LCD_MISO"), baudrate=4000000
    )
    display = Display(spi, dc=Pin("LCD_D/C"), cs=Pin("LCD_CS"), rst=Pin("LCD_RESET"))
    display.display_on()
    display.clear()
    led.on()  # shotgun debugging, embedded style
    backlight.on()
    
    # use default portrait settings: x = 0..239, y = 0..319
    dx = 3
    dy = 4
    x = 3
    y = 4
    i = 0
    
    try:
        while True:
            # display.draw_pixel(x, y, wheel565(i))
            display.fill_hrect(x, y, 3, 4, wheel565(i))
            i = (i + 1) % 256
            x = x + dx
            y = y + dy
            if x <= 4:
                dx = -dx
            if x >= 234:
                dx = -dx
            if y <= 5:
                dy = -dy
            if y >= 313:
                dy = -dy
    except:
        backlight.off()
        led.off()
        display.display_off()
    
  • INA219 Current Sensor and MicroPython

    More Micropython programmers — and especially beginners — should know about Awesome MicroPython. It’s a community-curated list of remarkably decent MicroPython libraries, frameworks, software and resources. If you need to interface to a sensor, look there first.

    For example, take the INA219 High Side DC Current Sensor. It’s an I²C sensor able to measure up to 26 V, ±3.2 A. It does this by measuring the voltage across a 0.1 ohm precision shunt resistor with its built-in 12-bit ADC. I got a customer return from the store that was cosmetically damaged but still usable, so I thought I’d try it with the simplest module I could find in Awesome MicroPython and see how well it worked.

    I guess I needed a test circuit too. Using all of what was immediately handy — a resistor I found on the bench and measured at 150.2 ohm — I came up with this barely useful circuit:

    simple circle with 3.3 V DC supply ad two resistors of 150.2 ohms and 0.1 ohms in series
    Should indicate a current of 3.3 / (150.2 + 0.1) = 21.96 mA

    The INA219 would be happier with a much higher current to measure, but I didn’t have anything handy that could do that.

    Looking in Awesome MicroPython’s Current section, I found robert-hh/INA219: INA219 Micropython driver. It doesn’t have much (okay, any) documentation, but it’s a very small module and the code is easy enough to follow. I put the ina219.py module file into the /lib folder of a WeAct Studio RP2040 board, and wrote the following code:

    # INA219 demo - uses https://github.com/robert-hh/INA219
    
    from machine import Pin, I2C
    import ina219
    
    i = I2C(0, scl=Pin(5), sda=Pin(4))
    print("I2C Bus Scan: ", i.scan(), "\n")
    
    sensor = ina219.INA219(i)
    sensor.set_calibration_16V_400mA()
    
    # my test circuit is 3V3 supply through 150.2 ohm resistor
    r_1 = 150.2
    r_s = 0.1  # shunt resistor on INA219 board
    
    # current is returned in milliamps
    print("Current       / mA: %8.3f" % (sensor.current))
    # shunt_voltage is returned in volts
    print("Shunt voltage / mV: %8.3f" % (sensor.shunt_voltage * 1000))
    # estimate supply voltage from known resistance * sensed current
    print("3V3 (sensed)  / mV: %8.3f" % ((r_1 + r_s) * sensor.current))
    
    

    with everything wired up like this (Blue = SDA, Yellow = SCL):

    breadboard with RP2040 pico board and INA219 sensor board benath it, and the 150 ohm wired as a circuit on the side
    all of the wires

    Running it produced this:

    I2C Bus Scan:  [64] 
    
    Current       / mA:   22.100
    Shunt voltage / mV:    2.210
    3V3 (sensed)  / mV: 3321.630
    

    So it’s showing just over 22 mA: pretty close to what I calculated!

  • The Quite Rubbish Clock, mk.2

    this is bad and I should feel bad

    In early 2013, I must’ve been left unsupervised for too long since I made The Quite Rubbish Clock:

    It still isn’t human readable …

    Written in (Owen Wilson voice) kind of an obsolete vernacular and running on hardware that’s now best described as “quaint”, it was still absurdly popular at the time. Raspberry Pis were still pretty new, and people were looking for different things to do with them.

    I happened across the JASchilz/uQR: QR Code Generator for MicroPython the other day, and remembered I had some tiny OLED screens that were about the same resolution as the old Nokia I’d used in 2013. I wondered: could I …?

    small microcontroller board with USB C cable attached and an OLED screen on top. The OLED is displaying a QR code which reads '172731'
    OLED Shield on a LOLIN S2 Mini: very smol indeed

    The board is a LOLIN S2 Mini with a OLED 0.66 Inch Shield on top, all running MicroPython. One limitation I found in the MicroPython QR library was that it was very picky about input formats, so it only displays the time as HHMMSS with no separators.

    Source, of course:

    # -*- coding: utf-8 -*-
    # yes, the Quite Rubbish Clock rides again ...
    # scruss, 2022-06-30
    # MicroPython on Lolin S2 Mini with 64 x 48 OLED display
    # uses uQR from https://github.com/JASchilz/uQR
    # - which has problems detecting times with colons
    
    from machine import Pin, I2C, RTC
    import s2mini  # on Lolin ESP32-S2 Mini
    import ssd1306
    from uQR import QRCode
    
    WIDTH = 64  # screen size
    HEIGHT = 48
    SIZE = 8  # text size
    r = RTC()
    
    # set up and clear screen
    i2c = I2C(0, scl=Pin(s2mini.I2C_SCL), sda=Pin(s2mini.I2C_SDA))
    oled = ssd1306.SSD1306_I2C(WIDTH, HEIGHT, i2c)
    oled.fill(0)
    
    
    def snazz():
        marquee = [
            "   **",
            "   **",
            "   **",
            "   **",
            "   **",
            "********",
            " ******",
            "  ****",
            "   **",
            " quite",
            "rubbish",
            " clock",
            "  mk.2",
            "<scruss>",
            " >2022<"
        ]
        for s in marquee:
            oled.scroll(0, -SIZE)  # scroll up one text line
            oled.fill_rect(0, HEIGHT-SIZE, WIDTH,
                           SIZE, 0)  # blank last line
            oled.text("%-8s" % s, 0, HEIGHT-SIZE)  # write text
            oled.show()
            time.sleep(0.25)
        time.sleep(5)
        oled.fill(1)
        oled.show()
    
    
    snazz()  # tedious crowd-pleasing intro
    
    qr = QRCode()
    while True:
        qr.add_data("%02d%02d%02d" % r.datetime()[4:7])
        qr.border = 1  # default border too big to fit small screen
        m = qr.get_matrix()
        oled.fill(1)
        for y in range(len(m)):
            for x in range(len(m[0])):
                # plot a double-sized QR code, centred, inverted
                oled.fill_rect(9 + 2*x, 1 + 2*y, 2, 2, not m[y][x])
        oled.show()
        time.sleep(0.05)
        qr.clear()
    
    

    If your output is glitchy, you might need to put the following in boot.py:

    import machine
    machine.freq(240000000)
    

    This increases the ESP32-S2’s frequency from 160 to 240 MHz.

    Update: there’s a fork of uQR that provides better character support, particularly those required for sending Wi-Fi Network config.

  • A new old calendar

    simulated dot-matrix printer on ruled paper layout of an ASCII-art Snoopy in WW1 Air Ace regalia yelling "Curse you Red Baron!" at his imaginary nemesis, and a 2022 calendar laid out on the facing page
    not seen the likes of this since ’78, I’ll be bound

    It’s unlikely anyone wanted a faux-lineprinter ASCII art calendar for 2022, but you’re getting one anyway. You can print this yourself:

    If you want to make your own, here’s a script: snoopycal.sh

    Credits:

    • Original “WW1 Fighter Pilot” Snoopy ASCII art from “SNOOPY.BA” for the DEC PDP-8, written by Mr Kay R. Fisher of DEC some time before July 1973. It’s referred to in the first printing of the “101 Basic Computer Games” book, which was published in 1973.
    • ncal, banner: their respective authors
    • pstext an ascii to PS filter by Dan Judd, usenet comp.lang.postscript, December 1989. I had to really mess around with the output of this program to use a custom font and add the music ruling, but it produces cleaner PostScript than the giant messes that enscript and a2ps have become
    • Font: mnicmp, by me. Based on the DecWriter II font.
    • iffy scripting, scribbly lines: also me.

  • I (U+1F494, BROKEN HEART) UTF-8

    Something has gone very wrong with the database encoding on this blog after a recent update, so all my lovely UTF-8 characters have gone mojibake.

    Trying to find ways to fix it. It may have to be manual. Remember, kids: have backups before letting WordPress upgrade!

    Here’s the Python equivalent of what I think the database has done:

    bytes("I ???? UTF-8", encoding='utf-8').decode(encoding='cp1252')
    'I 💔 UTF-8'

    Quite why my hosting thought a character encoding from last century was appropriate, I’ll never know.

    Update, November 2023: kinda-sort fixed the backend, but the encoding is still weird — can we…?

  • Autumn in Canada: PicoMite version

    Autumn in Canada: PicoMite version

    So I ported autumn in canada from OpenProcessing to PicoMite BASIC on the Raspberry Pi Pico:

    a small black screen images with text in the centre: autumn in canada scruss, 2021-11 just watch ...
    no leaves
    a small black screen images with text in the centre: autumn in canada scruss, 2021-11 just watch ... with one red and one orange maple leaf sitting on top of it
    a couple of leaves
    a small black screen images with text in the centre: autumn in canada scruss, 2021-11 just watch ... with four red/yellow/orange maple leaves sitting on top of it
    more leaves
    a small black screen images with text in the centre: autumn in canada scruss, 2021-11 just watch ... with sixteen simulated fallen maple leaves mostly covering it
    plenty of leaves
    a small black screen image completely covered with many simulated fallen maple leaves
    far too many leaves

    The biggest thing that tripped me up was that PicoMite BASIC starts arrays at 0. OPTION BASE 1 fixes that oversight. It would have been nice to have OpenProcessing’s HSV colour space, and an editor that could handle lines longer than 80 characters that didn’t threaten to bomb out if you hit the End key, but it’ll serve.

    Source below:

    ' autumn in canada
    ' scruss, 2021-11
    ' a take on my https://openprocessing.org/sketch/995420 for picomite
    
    OPTION base 1
    RANDOMIZE TIMER
    ' *** initialize polar coords of leaf polygon and colour array
    DIM leaf_rad(24), leaf_ang(24), px%(24), py%(24)
    FOR i=1 TO 24
        READ leaf_rad(i)
    NEXT i
    FOR i=1 TO 24
        READ x
        leaf_ang(i)=RAD(x)
    NEXT i
    
    DIM integer c%(8)
    FOR i=1 TO 8
        READ r%, g%, b%
        c%(i)=RGB(r%,g%,b%)
    NEXT i
    
    ' *** set up some limits
    min_scale%=INT(MIN(MM.HRES, MM.VRES)/8)
    max_scale%=INT(MIN(MM.HRES, MM.VRES)/6)
    min_angle=-30
    max_angle=30
    min_x%=min_scale%
    min_y%=min_x%
    max_x%=MM.HRES - min_x%
    max_y%=MM.VRES - min_y%
    
    CLS
    TEXT MM.HRES/2, INT(MM.VRES/3), "autumn in canada", "CM"
    TEXT MM.HRES/2, INT(MM.VRES/2), "scruss, 2021-11", "CM"
    TEXT MM.HRES/2, INT(2*MM.VRES/3), "just watch ...", "CM"
    
    kt%=0
    DO
        cx% = min_x% + INT(RND * (max_x% - min_x%))
        cy% = min_y% + INT(RND * (max_y% - min_y%))
        angle = min_angle + RND * (max_angle - min_angle)
        sc% = min_scale% + INT(RND * (max_scale% - min_scale%))
        col% = 1 + INT(RND * 7)
        leaf cx%, cy%, sc%, angle, c%(7), c%(col%)
        kt% = kt% + 1
    LOOP UNTIL kt% >= 1024
    
    END
    
    SUB leaf x%, y%, scale%, angle, outline%, fill%
        FOR i=1 TO 24
            px%(i) = INT(x% + scale% * leaf_rad(i) * COS(RAD(angle)+leaf_ang(i)))
            py%(i) = INT(y% - scale% * leaf_rad(i) * SIN(RAD(angle)+leaf_ang(i)))
        NEXT i
        POLYGON 24, px%(), py%(), outline%, fill%
    END SUB
    
    ' radii
    DATA 0.536, 0.744, 0.608, 0.850, 0.719
    DATA 0.836, 0.565, 0.589, 0.211, 0.660, 0.515
    DATA 0.801, 0.515, 0.660, 0.211, 0.589, 0.565
    DATA 0.836, 0.719, 0.850, 0.608, 0.744, 0.536, 1.000
    ' angles
    DATA 270.000, 307.249, 312.110, 353.267, 356.540
    DATA 16.530, 18.774, 33.215, 3.497, 60.659, 72.514
    DATA 90.000, 107.486, 119.341, 176.503, 146.785, 161.226
    DATA 163.470, 183.460, 186.733, 227.890, 232.751, 270.000, 270.000
    ' leaf colours
    DATA 255,0,0, 255,36,0, 255,72,0, 255,109,0
    DATA 255,145,0, 255,182,0, 255,218,0, 255,255,0
    

    You could probably use AUTOSAVE and paste the text into the PicoMite REPL. I used an ILI9341 SPI TFT LCD Touch Panel with my Raspberry Pi Pico along with some rather messy breadboard wiring.

    Fun fact: the maple leaf polygon points are derived from the official definition of the flag of Canada.

  • p-touch Pico pin labels

    breadboard with Raspberry Pi Pico attached, and two labels running down the sides with the pin names
    Pico pin labels: not bad for a first try

    This worked better than I expected. The tricky parts are trimming the edges and getting it them straight.

    Here’s the image to print on your label maker:

    combined Pico pin labels printed sideways on a tape label
    print on 12.7 mm tape
  • Raspberry Pi Zero 2 W: slides and thermals

    Raspberry Pi Zero 2 W: slides and thermals

    Slides from last night’s talk:

    It’s impossible to have a Raspberry Pi Zero overheat unless you overclock it. That’s why you don’t get any cases for it with fans or heat sinks. The quad-core Raspberry Pi Zero 2 W, though, has the potential to do so. Here are some numbers:

    • Used official case with lid fitted: increases SoC temperature +3 °C over free air
    • Test – CPUBurn: https://github.com/pmylund/cpuburn
    • Tested 4, 3 and 2 cores burning in 32-bit and 64-bit modes: time from idle to throttling (80 °C) measured
    • GPU overheat not tested.
    line graph of cpu temperature against time. Temperature rises sharply from about 47 degrees C to 82 degrees C in around four minutes
    All 4 cores burning, 64-bit mode: time to overheat = under 3½ minutes
    line graph of cpu temperature against time. Temperature rises sharply from about 47 degrees C to 82 degrees C in just over four minutes
    All 4 cores burning, 32-bit mode: time to overheat = just over 4 minutes
    line graph of cpu temperature against time. Temperature rises moderately from about 47 degrees C to 81 degrees C in around seven minutes
    3 out of 4 cores burning, 64-bit mode: time to overheat = just over 7 minutes
    line graph of cpu temperature against time. Temperature rises slowly from about 47 degrees C to 81 degrees C in around ten minutes
    3 out of 4 cores burning, 32-bit mode: time to overheat = 9½ minutes
    line graph of cpu temperature against time. Temperature rises very slowly, reach 70 degrees C in 40 minutes and then only rising very slightly to about 73 degrees C in the entire run time of 3 hours 20 minutes
    2 out of 4 cores burning, 32-bit mode: time to overheat = basically never

    Unless you’re doing things that might indicate you should be using a bigger computer, a Raspberry Pi Zero 2 W won’t overheat and doesn’t need any form of cooling. If you’re overclocking, well … it’s your choice to have cooling equipment worth more than the computer it’s trying to cool.

  • Raspberry Pi Zero 2 W: initial performance

    Running A Pi Pie Chart turned out some useful performance numbers. It’s almost, but not quite, a Raspberry Pi 3B in a Raspberry Pi Zero form factor.

    32-bit mode

    Running stock Raspberry Pi OS with desktop, compiled with stock options:

    pie chart comparing multi-thread numeric performance of Raspberry Pi Zero 2 W: slightly faster than a Raspberry Pi 2B
    multi-thread results
    pie chart comparing single-thread numeric performance of Raspberry Pi Zero 2 W: slightly faster than a Raspberry Pi 2B
    single-thread results
    time ./pichart-openmp -t "Zero 2W, OpenMP"
    pichart -- Raspberry Pi Performance OPENMP version 36
    
    Prime Sieve          P=14630843 Workers=4 Sec=2.18676 Mops=427.266
    Merge Sort           N=16777216 Workers=8 Sec=1.9341 Mops=208.186
    Fourier Transform    N=4194304 Workers=8 Sec=3.10982 Mflops=148.36
    Lorenz 96            N=32768 K=16384 Workers=4 Sec=4.56845 Mflops=705.102
    
    The Zero 2W, OpenMP has Raspberry Pi ratio=8.72113
    Making pie charts...done.
    
    real	8m20.245s
    user	15m27.197s
    sys	0m3.752s
    
    -----------------------------
    
    time ./pichart-serial -t "Zero 2W, Serial"
    pichart -- Raspberry Pi Performance Serial version 36
    
    Prime Sieve          P=14630843 Workers=1 Sec=8.77047 Mops=106.531
    Merge Sort           N=16777216 Workers=2 Sec=7.02049 Mops=57.354
    Fourier Transform    N=4194304 Workers=2 Sec=8.58785 Mflops=53.724
    Lorenz 96            N=32768 K=16384 Workers=1 Sec=17.1408 Mflops=187.927
    
    The Zero 2W, Serial has Raspberry Pi ratio=2.48852
    Making pie charts...done.
    
    real	7m50.524s
    user	7m48.854s
    sys	0m1.370s

    64-bit

    Running stock/beta 64-bit Raspberry Pi OS with desktop. Curiously, these ran out of memory (at least, in oom-kill‘s opinion) with the desktop running, so I had to run from console. This also meant it was harder to capture the program run times.

    The firmware required to run in this mode should be in the official distribution by now.

    pie chart comparing 64 bit multi-thread numeric performance of Raspberry Pi Zero 2 W: slightly faster than a Raspberry Pi 2B
    multi-thread, 64 bit: no, I can’t explain why Lorenz is better than a 3B+
    pie chart comparing 64 bit single-thread numeric performance of Raspberry Pi Zero 2 W: slightly faster than a Raspberry Pi 2B
    single thread, again with the bump in Lorenz performance
    pichart -- Raspberry Pi Performance OPENMP version 36
    
    Prime Sieve          P=14630843 Workers=4 Sec=1.78173 Mops=524.395
    Merge Sort           N=16777216 Workers=8 Sec=1.83854 Mops=219.007
    Fourier Transform    N=4194304 Workers=4 Sec=2.83797 Mflops=162.572
    Lorenz 96            N=32768 K=16384 Workers=4 Sec=2.66808 Mflops=1207.32
    
    The Zero2W-64bit has Raspberry Pi ratio=10.8802
    Making pie charts...done.
    
    -------------------------
    
    pichart -- Raspberry Pi Performance Serial version 36
    
    Prime Sieve          P=14630843 Workers=1 Sec=7.06226 Mops=132.299
    Merge Sort           N=16777216 Workers=2 Sec=6.75762 Mops=59.5851
    Fourier Transform    N=4194304 Workers=2 Sec=7.73993 Mflops=59.6095
    Lorenz 96            N=32768 K=16384 Workers=1 Sec=9.00538 Mflops=357.7
    
    The Zero2W-64bit has Raspberry Pi ratio=3.19724
    Making pie charts...done.

    The main reason for the Raspberry Pi Zero 2 W appearing slower than the 3B and 3B+ is likely that it uses LPDDR2 memory instead of LPDDR3. 64-bit mode provides is a useful performance increase, offset by increased memory use. I found desktop apps to be almost unusably swappy in 64-bit mode, but there might be some tweaking I can do to avoid this.

    Unlike the single core Raspberry Pi Zero, the Raspberry Pi Zero 2 W can be made to go into thermal throttling if you’re really, really determined. Like “3 or more cores running flat-out“-determined. In my testing, two cores at 100% (as you might get in emulation) won’t put it into thermal throttling, even in the snug official case closed up tight. More on this later.

    (And a great big raspberry blown at Make, who leaked the Raspberry Pi Zero 2 W release a couple of days ago. Not classy.)

  • Another Raspberry Pi Pico language: MMBasic

    It’s very much a work in progress, but Geoff Graham and Peter Mather’s MMBasic runs nicely on the Raspberry Pi Pico. Development is mostly coordinated on TheBackShed.com forum.

    It supports an impressive range of displays and peripherals. The project gives me a very distinct “This is how we do things” vibe, and it’s quite unlike any other Raspberry Pi Pico project.

    To show you what MMBasic code looks like, here’s a little demo that uses one of those “Open Smart” LED traffic lights on physical pins 14-16 which cycles through the phases every few seconds:

    ' traffic light on gp10-12 (green, yellow, red), pins 14-16
    
    ' set up ports for output
    FOR i=14 TO 16
      SETPIN i, DOUT
      PIN(i)=0
    NEXT i
    
    red=16
    amber=15
    green=14
    
    DO
      ' green on for 5 seconds
      PIN(red)=0
      PIN(green)=1
      PAUSE 5000
      ' amber on for 3 seconds
      PIN(green)=0
      PIN(amber)=1
      PAUSE 3000
      ' red on for 5 seconds
      PIN(amber)=0
      PIN(red)=1
      PAUSE 5000
    LOOP
    
  • gecko at the watering hole, forever

    • Video downloaded using youtube-dl
    • Resized to 360p and 30 fps using ffmpeg
    • Loop found and resized using MoviePy, with ffmpeg used to create the gif
    • gif optimized using gifsicle -O3

    Result: 320×180, 22 frames, 128 colours, ~ 600 KB.

  • Some okay CMYK results from DrawingBot, finally …

    decorative 8-sided symmetrical square tile sketched out in cyan, magenta, yellow and grey felt tip pen on a plotter
    drawn using a Roland DXY-1300 plotter on Strathmore Multimedia using DeSerres medium tip pens, ~60 minutes plotting time, 180 × 180 mm

    After a tonne of faffing about, I finally got something out of my plotter using Drawing Bot. I’d heard about it during the Bold Machines’ Intro to Pen Plotters course I’m taking, and the results that other people were getting looked encouraging. But for me, they weren’t great.

    Maybe I was choosing too large images, but my main problem was ending up with plots with far too many lines: these would take days to plot. The controls on Drawing Bot also seemed limited: density and resolution seemed to be the only controls that do much. Drawing Bot itself wasn’t very reliable: it would sometimes go into “use all the cores!” mode when it was supposed to be idling. It would also sometimes zoom in on part of the image and fail to unzoom without quitting. Is a 32 GB i7 8-core (oldish, but still game) too little for this software? Forget any of the Voronoi plots if you want to see results today.

    The source image was a geometric tile that I’d frisketed out years ago, forgotten about, and then found when I unstuck it from under a stack of papers. It’s somewhat artisanally coloured by me in watercolour, and the mistakes and huge water drop are all part of its charm:

    geometric tile picked out in brown, red, pink, green  and various shades of faded blue, separated by rough white frisket lines
    source image for plotter output

    If WordPress will allow an SVG, here’s what Drawing Bot made of it:

    scribbly linedrawing of the tile image in CMYK process colours
    Drawing Bot SVG output: yes, it’s that faint

    I do like the way that Drawing Bot seems to have ignored some colours, like the rose pink around the outside. The green border really is mostly cyan with a touch of black.

    I haven’t magically found perfect CMYK pens in HP/Roland pen format. I couldn’t even find the Schwan-Stabilo Point 88 pens that Lauren Gardner at Bold Machines recommends. But the local DeSerres did deliver a selection of their own-brand 1.0mm Mateo Markers that are physically close to the Point 88s in size, but use a wider 1 mm fibre tip. They are also cheap; did I mention that?

    The colours I chose were:

    • for cyan: Mint Green; RGB colour: #52C3A5; SKU: DFM-53
    • for magenta: Neon Pink; RGB colour: #FF26AB; SKU: DFM-F23
    • for yellow: Neon Yellow; RGB colour: #F3DE00; SKU: DFM-F01
    • for black: Green Grey 5; RGB colour: #849294; SKU: DFM-80

    The RGB colours are from DeSerres’ website, and show that I’m not wildly off. Target process colours are the top row versus nominal pen colours on the bottom:

    target vs pen CMYK colours
    yes, there are fluo colours in there

    I knew to avoid pure black, as it would overpower everything in the plot.

    To make the pens work with the DXY-1300, I modified juliendorra/3D-printable-plotter-adapters-for-pens-and-refills: Use your favorite pens with vintage HP plotters: parametric code to create custom adapters to work the the DeSerres pens. Here are my changed files, just in case my PR isn’t accepted:

    Overall, it plotted quite well. I plotted directly from Inkscape, one layer/pen at a time, from light (yellow) to dark (grey). Using the pen 1 slot had its disadvantages: the DXY has little pen boots to stop the pens drying, but these unfortunately get filled with old ink. The scribbly dark markings in the NNE and SSW orange kites in the plot are from the yellow pen picking up old black ink from the pen boot. Next time I’ll clean the plotter better.