I like Arduino Nanos. They’re cheap. They work. They’re small. But they’re a bit fiddly, what with their breadboard legs and tiny pin labels. Wouldn’t it be nicer to use them as self-contained units, with Dupont wires coming from the pins?
This is where nspohrer’s Arduino Nano case with completely accessible pins comes in:
Flip it over, label the pins, and you’ve got a polished little microcontroller in a box. And do I have just the right label for you …
I’ve even included the original SVG so you can make custom versions. Please ignore the “micro” in the name … they are really for the Nano.
So Dr. Blake “PROTODOME” Troise (previously) made a chiptune album that’s entirely synthesized by an Atmel/Microchip ATmega328P microcontroller in realtime. And every chip needs a PCB, right? So Blake released the album as a physical device you can solder up for yourself.
Of course, having the PCB lying flat doesn’t allow you to see Marianne Thompson’s great pixel cover art, or read the liner notes on the back — and risks having the circuit short out on random tinny things on your desk. (Maybe that’s just my desk, though.)
This stand allows you to display the board at a convenient 75° angle, but also allows the PCB to be flipped forward so you can read the liner notes comfortably. Yeah, I may have been a crate-digger at one time.
- PROTODOME — https://protodome.com/
- 4000AD album on Bandcamp, pay what you can — https://protodome.bandcamp.com/album/4000AD
- About the 4000AD board — https://protodome.com/4000AD/
- Although not part of the project, the 3D printed headphones in the cover picture are from Print+ — https://www.print.plus/
(or Thingiverse link: https://www.thingiverse.com/thing:4579706)
I’m really enjoying Elisabeth Fraser’s The Glint Game, a delightfully nerdy pattern diversion that uses real metal type.
For something to do with my head, I’m taking the RAC Advanced Ham Radio course. The exam uses a non-programmable scientific calculator. I thought that all my calculators were programmable, but we found this one lurking in the basement and it’s just perfect:
This is one of the few calculators I’ve seen that both displays and takes inputs in SI units. How to put it into SI engineering display mode is explained in this delightful (archived) site Casio fx-115MS.
Entering numbers with SI prefixes is simple: type the number, then Shift and hit the prefix. So to enter 300000, you’d type 300 Shift 4 to get 300 k.
You do have to be a little careful reading the display in this mode, though. The display above reads 221 × 10-3 (from the m at right), or 0.221.
I don’t see any calculator in Casio’s current range that offers this handy feature. Guess I’m lucky I found it before the exam!
Audio can be a bit dismal on a Raspberry Pi. Once you get a configuration that works, sometimes you’re not sure how you got there and you’ll do anything to keep that arcane setup going. It’s better than it was.
Speech synthesis or TTS adds an extra layer for potential failure. One of the popular Linux TTS systems, eSpeak, hasn’t seen much development in almost a decade and seems to only work through workarounds and hand-waving.
Thankfully, there’s a fork of eSpeak that is maintained: espeak-ng. Better yet, it’s packaged with Raspberry Pi OS and can be installed quite easily:
sudo apt install espeak-ng espeak-ng-data libespeak-ng-dev
In my simple tests, it output everything I expected of it.
eSpeak had a Python module that kinda worked, but espeak-ng’s is much more ambitious, and (mostly) does what it sets out to do. You can install it like this:
sudo pip3 install py-espeak-ng
py-espeak-ng has some documentation, but it’s still got some trial and error in getting it to work. The biggest issue that held me up was that the module needs to be initialized with a voice that espeak-ng already knows about. If you don’t specify a voice, or specify one that the system doesn’t know about, you won’t get any errors — but you won’t get any output, either.
Here’s a small Python example that you’ll probably want to try with no-one else within earshot. It repeats the same English phrase (a favourite of elocution teachers) in every English regional language that espeak-ng knows about. In addition, since I’m a dictionary nerd, it outputs phonetics too.
#!/usr/bin/python3 # -*- coding: utf-8 -*- # an espeakng elocution lesson from scruss, 2020-07 # I suffered this at school, now you get to as well! # You will need to: # sudo apt install espeak-ng espeak-ng-data libespeak-ng-dev # sudo pip3 install py-espeak-ng from espeakng import ESpeakNG from time import sleep # you have to initialize with a voice that exists # `espeak-ng --voices=en` will list English ones esng = ESpeakNG(voice='en-gb') esng.pitch = 32 esng.speed = 150 phrase = "Father's car is a Jaguar and pa drives rather fast. "\ "Castles, farms and draughty barns, all go charging past." print(phrase) print() for voice in esng.voices: if voice['language'].startswith('en-'): print('Using voice:', voice['language'], 'for', voice['voice_name'], '-') esng.voice = voice['language'] ipa = esng.g2p(phrase, ipa=2) print(voice['language'], 'phonetics:', ipa) esng.say(phrase, sync=True) print() sleep(0.1)
Be thankful you can’t hear the output. The IPA output, however, is a thing of beauty:
./espeakNG_test.py Father's car is a Jaguar and pa drives rather fast. Castles, farms and draughty barns, all go charging past. Using voice: en-029 for English_(Caribbean) - en-029 phonetics: fˈɑːdaz kˈɑ͡əɹ ɪz a d͡ʒˈaɡwɑ͡ə and pˈɑː dɹˈa͡ɪvz ɹˈɑːda fˈa͡astkˈa͡asɛlzfˈɑ͡əmz and dɹˈa͡afti bˈɑ͡ənzˈɔːl ɡˌo͡ʊ t͡ʃˈɑ͡əd͡ʒɪn pˈa͡ast Using voice: en-gb for English_(Great_Britain) - en-gb phonetics: fˈɑːðəz kˈɑːɹ ɪz ɐ d͡ʒˈaɡwɑː and pˈɑː dɹˈa͡ɪvz ɹˈɑːðə fˈastkˈasə͡lzfˈɑːmz and dɹˈafti bˈɑːnzˈɔːl ɡˌə͡ʊ t͡ʃˈɑːd͡ʒɪŋ pˈast Using voice: en-gb-scotland for English_(Scotland) - en-gb-scotland phonetics: fˈa:ðɜz kˈaːr ɪz ɐ d͡ʒˈaɡwaːr and pˈa: drˈa͡ɪvz rˈa:ðɜ fˈa:stkˈa:sə͡lzfˈaːrmz and drˈa:fte bˈaːrnzˈɔːl ɡˌoː t͡ʃˈaːrd͡ʒɪŋ pˈa:st …
How many CPU hours did I burn in the early 1990s rendering bits of the Mandelbrot Set? A lot, mainly because I was doing it in BASIC on an unexpanded 8 MHz Commodore Amiga A500. The image below that Fraqtive rendered in almost no time would have taken me days:
But it turns out that the first rendering of what we now call the Mandelbrot set wasn’t produced by Benoit Mandelbrot, but by Brooks & Matelski a year or two earlier:
What I’ve tried to do — and come close, but not actually managed to exactly replicate — is create period-appropriate code to reproduce that graphic. Since the paper was presented in 1978, there’s a fair chance that the authors had access to a machine running FORTRAN-77 or a near equivalent. FORTRAN’s particularly good for this:
- it has a built-in COMPLEX type that extends regular mathematical functions;
- it has just good enough string handling to output a line of spaces/asterisks. I would not have wanted to write this in FORTRAN-66, as that language had no string manipulation facilities at all.
So here’s the code. It should compile on any Fortran compiler:
PROGRAM BRKMAT ! GENERATE FIGURE FROM BROOKS-MATELSKI PAPER C.1978 ! THAT EVENTUALLY BECAME KNOWN AS THE MANDELBROT SET ! - SCRUSS, 2020-06 ! REF: BROOKS, ROBERT, AND J. PETER MATELSKI. ! "THE DYNAMICS OF 2-GENERATOR SUBGROUPS OF PSL (2, C)." ! RIEMANN SURFACES AND RELATED TOPICS: PROCEEDINGS OF THE ! 1978 STONY BROOK CONFERENCE, ! ANN. OF MATH. STUD. VOL. 97. 1981: FIG. 2, P. 81 REAL MAP, CR, CI INTEGER I, J, K, M, ROWS, COLS, MAXIT COMPLEX C, Z PARAMETER (ROWS=31, COLS=70, MAXIT=36) CHARACTER*80 OUT CHARACTER CH*1 DO J=1,ROWS CI=MAP(REAL(J), 1.0, REAL(ROWS), -0.89, 0.89) DO I=1,COLS CR=MAP(REAL(I), 1.0, REAL(COLS), -2.0, 0.45) C=CMPLX(CR, CI) Z=CMPLX(0.0, 0.0) CH='*' DO 100, K=1,MAXIT Z = Z**2 + C IF (ABS(Z) .GT. 2) THEN CH=' ' GO TO 101 END IF 100 CONTINUE 101 OUT(I:I)=CH END DO WRITE(*,*)OUT END DO END REAL FUNCTION MAP(X, XMIN, XMAX, YMIN, YMAX) REAL X, XMIN, XMAX, YMIN, YMAX MAP = YMIN + (YMAX - YMIN) * ((X - XMIN) / (XMAX - XMIN)) END
The results are close:
but not quite right. Maybe Brooks & Matelski had access to an Apple II and wrote something in BASIC? I could be entirely period-accurate and write something in PDP-8 BASIC on my SBC6120, but not today.
It really is much easier using a language with complex number support when working with the Mandelbrot set. Here’s the same program in Python3, which bears more of a resemblance to FORTRAN-77 than it might admit:
#!/usr/bin/python3 # brkmat - Brooks-Matelski proto ASCII Mandelbrot set - scruss, 2020-06 # -*- coding: utf-8 -*- def valmap(value, istart, istop, ostart, ostop): return ostart + (ostop - ostart) * ((value - istart) / (istop - istart)) rows = 31 cols = 70 maxit = 36 for y in range(rows): ci = valmap(float(y + 1), 1.0, float(rows), -0.89, 0.89) for x in range(cols): cr = valmap(float(x + 1), 1.0, float(cols), -2.0, 0.45) c = complex(cr, ci) z = complex(0.0, 0.0) ch = '*' for k in range(maxit): z = z**2 + c if (abs(z) > 2.0): ch = ' ' break print(ch, end='') print()
I found out about the Brooks-Matelski paper from this article: Who Discovered the Mandelbrot Set? – Scientific American. It’s none too complimentary towards Benoit Mandelbrot.
I’ve extended the MicroPython examples for the BrainPad Classic so that all of the devices work: scruss/brainpad-micropython: Micropython examples for the BrainPad Classic (BP2) from GHI Electronics.
The ones that already worked in the original examples repo are:
- light sensor
- OLED screen
- temperature sensor: although my calibration may be a bit off on the MCP9701a used on the board
- timer blink example: STM32 Timers are cool and we should use them
- PWM RGB LED example: floating-point silliness with HSV(ish) Colour Wheel in Python
- buzzer: simple tones plus tunes (in RTTTL) via dhylands / upy-rtttl
- servos: I may have forgotten to put the example in there, but the standard Servo(1) code should work.
Yes, it would be nice to have a slick unified library like the BBC micro:bit does. For later, though.
nomming from our deck
#!/usr/bin/python3 # -*- coding: utf-8 -*- # colourshen.py - stdin to rainbow stdout # scruss, 2020-06 from colors import * # see https://pypi.org/project/ansicolors/ import sys wheel_pos = 0 def cos_wheel(pos): # Input a value 0 to 255 to get a colour value. # scruss (Stewart Russell) - 2019-03 - CC-BY-SA from math import cos, pi if pos < 0: return (0, 0, 0) pos %= 256 pos /= 255.0 return (int(255 * (1 + cos(pos * 2 * pi)) / 2), int(255 * (1 + cos((pos - 1 / 3.0) * 2 * pi)) / 2), int(255 * (1 + cos((pos - 2 / 3.0) * 2 * pi)) / 2)) def hex_wheel(pos): rgb = cos_wheel(pos) return('#%02x%02x%02x' % rgb) def wheel_print(s): global wheel_pos incr = int(256/(1+len(s)))-1 if incr < 1: incr = 1 for c in s: print(color(c, fg=hex_wheel(wheel_pos)), end='') wheel_pos = (wheel_pos+incr) % 256 print() for txt in sys.stdin: wheel_print(txt.rstrip())
(fixed a very obvious ahem! in the code, hope no-one noticed …)