I’d been surviving on a series of sub-$50 multimeters for years. They’d give an approximation of a reading,then fail miserably in a variety of stupid ways. The last one, a rip-off of an Extech, decided to show me how its wires were connected to the probes. “Barely” is a fair description.
So I thought I’d buy a decent meter. One that had heft and gravitas, like the Avo 8 that my dad used to bring home from work. The Avo — seemingly constructed from bakelite, glass and lead — didn’t just take readings, it told you The Truth on its mirrored scale.
So I bought an Agilent. Reliable company, all the right features, beeps politely only when required; a very, very sensible meter. Then I found these in the package:
Dude, what?! Skins on a meter? Meters aren’t toys. Meters are sensible things used by sensible people. We don’t want our work distracted by thoughts of Space!, America!, Sports!, or Some Kind of Bug Thing Eww Squish It Squish It! If you were able to get “skins” for the Avo 8, they would be about Wisden, sheds, and the TSR2.
Pretty much everyone tries the RGB colour cycler when they get their first Arduino. This variant cycles through the HSV colour wheel, though at fixed saturations and values.
Code:
// HSV fade/bounce for Arduino - scruss.com - 2010/09/12
// Note that there's some legacy code left in here which seems to do nothing
// but should do no harm ...
// don't futz with these, illicit sums later
#define RED 9 // pin for red LED
#define GREEN 10 // pin for green - never explicitly referenced
#define BLUE 11 // pin for blue - never explicitly referenced
#define SIZE 255
#define DELAY 10
#define HUE_MAX 6.0
#define HUE_DELTA 0.01
long deltas[3] = {
5, 6, 7 };
long rgb[3];
long rgbval;
// for reasons unknown, if value !=0, the LED doesn't light. Hmm ...
// and saturation seems to be inverted
float hue=0.0, saturation=1.0, value=1.0;
/*
chosen LED SparkFun sku: COM-09264
has Max Luminosity (RGB): (2800, 6500, 1200)mcd
so we normalize them all to 1200 mcd -
R 1200/2800 = 0.428571428571429 = 109/256
G 1200/6500 = 0.184615384615385 = 47/256
B 1200/1200 = 1.0 = 256/256
*/
long bright[3] = {
109, 47, 256};
long k, temp_value;
void setup () {
randomSeed(analogRead(4));
for (k=0; k<3; k++) {
pinMode(RED + k, OUTPUT);
rgb[k]=0;
analogWrite(RED + k, rgb[k] * bright[k]/256);
if (random(100) > 50) {
deltas[k] = -1 * deltas[k]; // randomize direction
}
}
}
void loop() {
hue += HUE_DELTA;
if (hue > HUE_MAX) {
hue=0.0;
}
rgbval=HSV_to_RGB(hue, saturation, value);
rgb[0] = (rgbval & 0x00FF0000) >> 16; // there must be better ways
rgb[1] = (rgbval & 0x0000FF00) >> 8;
rgb[2] = rgbval & 0x000000FF;
for (k=0; k<3; k++) { // for all three colours
analogWrite(RED + k, rgb[k] * bright[k]/256);
}
delay(DELAY);
}
long HSV_to_RGB( float h, float s, float v ) {
/* modified from Alvy Ray Smith's site: http://www.alvyray.com/Papers/hsv2rgb.htm */
// H is given on [0, 6]. S and V are given on [0, 1].
// RGB is returned as a 24-bit long #rrggbb
int i;
float m, n, f;
// not very elegant way of dealing with out of range: return black
if ((s<0.0) || (s>1.0) || (v<0.0) || (v>1.0)) {
return 0L;
}
if ((h < 0.0) || (h > 6.0)) {
return long( v * 255 ) + long( v * 255 ) * 256 + long( v * 255 ) * 65536;
}
i = floor(h);
f = h - i;
if ( !(i&1) ) {
f = 1 - f; // if i is even
}
m = v * (1 - s);
n = v * (1 - s * f);
switch (i) {
case 6:
case 0:
return long(v * 255 ) * 65536 + long( n * 255 ) * 256 + long( m * 255);
case 1:
return long(n * 255 ) * 65536 + long( v * 255 ) * 256 + long( m * 255);
case 2:
return long(m * 255 ) * 65536 + long( v * 255 ) * 256 + long( n * 255);
case 3:
return long(m * 255 ) * 65536 + long( n * 255 ) * 256 + long( v * 255);
case 4:
return long(n * 255 ) * 65536 + long( m * 255 ) * 256 + long( v * 255);
case 5:
return long(v * 255 ) * 65536 + long( m * 255 ) * 256 + long( n * 255);
}
}
Dude, what?! Skins on a meter? Meters aren’t toys. Meters are sensible things used by sensible people. We don’t want our work distracted by thoughts of Space!, America!, Sports!, or Some Kind of Bug Thing Eww Squish It Squish It! If you were able to get “skins” for the Avo 8, they would be about Wisden, sheds, and the TSR2.