Tag: Arduino

All things Arduino

USB Charger: Abosi Waveforms

For comparison with the Anonymous White Charger of Doom, I bought a trio of Abosi USB chargers:

Abosi charger – dataplate

The symbology indicates it’s UL, but not CE, listed. Consumer Reports has a guide to some of the symbols; I can’t find anything more comprehensive.

Applying the same 8 Ω + 100 µF load as before:

Abosi charger – 8 ohm 100 uF detail – 100 ma-div

The voltage (yellow) and current (green, 100 mA/div) waveforms look downright tame compared to some of the other chargers!

I made a cursory attempt to crack the case open, but gave up before doing any permanent damage. Hey, that UL listing (and, presumably, the interior details) means they’re three times the price of those Anonymous chargers!

2020-07-02
Anonymous White USB Charger: Teardown

Prompted by ericscott’s comment, I had to tear down the Anonymous White USB Charger to see what caused the bizarre current waveform when connected to the Arduino in a Glass Tile:

Tiles 2×2 – anon white charger – pulse detail – 50 mA-div

Start by grabbing opposite corners in a small vise and gently cracking the solvent-bonded joint between the sections:

Anon white charger – case cracking

Pull the base past the molded latches:

Anon white charger – case opened

Behold: components!

Anon white charger – PCB top

On both sides of both PCBs!

Anon white charger – PCB bottom

The top half of both boards, above the isolation cut, handles the line voltage and the lower half handles the 5 V USB output. You’ll note the absence of extra-cost parts like voltage feedback or ahem safety fuses.

The IC on the right half is labeled DP3773, which doesn’t seem to exist, but is surely similar to the LP3773 Low-Power Off-Line / PSR Controller.

Treating the whole regulator as a black box simplifies the schematic:

Anonymous white charger – schematic

The cap bridging the two sides should be a Y capacitor, but it’s an ordinary 1 nF ceramic cap with a generous 1 kV rating. As far as I can tell, having it inject AC line noise directly into the +5 V side of the USB supply is just a bonus.

The base markings again:

Anonymous white charger – dataplate

Whaddaya want for a buck, right?

Other folks give better teardown pr0n …

2020-06-26
Glass Tiles: USB Charger Current Waveforms

Looking at what comes out of various USB chargers, with the Tek current probe monitoring the juice:

USB Current-Probe Extender – in action

First, a known-good bench supply set to 5.0 V:

Tiles 2×2 – bench supply – 50 mA-div

The yellow trace is the Glass Tile Heartbeat output, which goes high during the active part of the loop. The purple trace shows the serial data going to the SK6812 RGBW LEDs. The green trace is the USB current at 50 mA/div, with the Glass Tile LED array + Arduino drawing somewhere between 50 and 100 mA; most of that goes to the LEDs.

The current steps downward by about 10 mA just after the data stream ends, because that’s where the LEDs latch their new PWM values. The code is changing a single LED from one color to another, so the current will increase or decrease by the difference of the two currents.

A charger from my Google Pixel 3a phone (actually made by Flextronics and, uniquely, UL listed), with Google’s ever-so-trendy and completely unreadable medium gray lettering on a light gray plastic body:

Google Pixel charger – dataplate

The current waveform looks only slightly choppy:

Tiles 2×2 – Google Flextronics charger – 50 mA-div

An AmazonBasics six-port USB charger ~~from~~ tested by Intertek:

AmazonBasics charger – dataplate

The waveform:

Tiles 2×2 – Amazon Basics Intertek Basics charger – 50 mA-div

A blackweb (their lack of capitalization) charger, also ~~made~~ tested by Intertek:

blackweb charger – dataplate

The current:

Tiles 2×2 – blackweb charger – 50 mA-div

Finally, one from a lot of dirt-cheap chargers from eBay:

Anonymous white charger – dataplate

Which has the most interesting current waveform of all:

Tiles 2×2 – anon white charger – 50 mA-div

A closer look:

Tiles 2×2 – anon white charger – pulse detail – 50 mA-div

From the 75 mA baseline, the charger is ramming 175 mA pulses at 24 kHz into the filter cap on the Arduino Nano PCB! The green trace has a few seconds of (digital) persistence, so you’re seeing a lot of frequency jitter; the pulses most likely come from a voltage comparator controlling the charger’s PWM cycle.

It’s about what one should expect for $1.28 apiece, right?

They’re down to $1.19 today: who knows what the waveform might be?

Update: Having gotten a clue from a comment posted instantly after I fat-fingered the schedule for this post, I now know Intertek is a testing agency, not a manufacturer.

2020-06-22
USB Current Probe Extender

Having gotten two answers from two USB meters, I figured it was time to get primal:

USB Current-Probe Extender – wiring

That’s a pair of USB breakout connectors and lengths of nice silicone wire (24 AWG power & 28 AWG data), with just enough slack for a Tek A6302 current probe:

USB Current-Probe Extender – in action

So I can see the actual current waveform of a Glass Tile box running from a bench power supply:

Tiles 2×2 – bench supply – 50 mA-div

The top trace is the firmware heartbeat from the Arduino Nano, the middle trace is the SK6812 LED data stream, and the bottom trace is the USB current at 50 mA/div. The current steps downward by about 10 mA (just after the data burst) when one of the tiles changes color and and LED shuts off.

The current probe reveals some mysteries, such as this waveform from a dirt-cheap USB charger:

Tiles 2×2 – anon white charger – 50 mA-div

I wonder why it’s ramming 100 mA current spikes into the circuit, too. At least now I can see what’s going on.

2020-06-16

Glass Tiles: Matrix for SK6812 PCBs

Tweaking the glass tile frame for press-fit SK6812 PCBs in the bottom of the array cells:

Glass Tile Frame - cell array - openscad — Glass Tile Frame – cell array – openscad

Which looks like this with the LEDs and brass inserts installed:

Glass Tile - 2x2 array - interior — Glass Tile – 2×2 array – interior

The base holds an Arduino Nano with room for wiring under the cell array:

Glass Tile Frame - base - openscad — Glass Tile Frame – base – openscad

Which looks like this after it’s all wired up:

Glass Tile - 2x2 array - wiring — Glass Tile – 2×2 array – wiring

The weird colors showing through the inserts are from the LEDs. The red thing in the upper left is a silicone insulation snippet. Yes, that’s hot-melt glue holding the Arduino Nano in place and preventing the PCBs from getting frisky.

Soak a handful of glass tiles overnight in paint stripper:

Glass Tiles - paint stripper soak — Glass Tiles – paint stripper soak

Whereupon the adhesive slides right off with the gentle application of a razor scraper. Rinse carefully, dry thoroughly, and snap into place.

Tighten the four M3 SHCS and it’s all good:

Glass Tile - 2x2 array - operating — Glass Tile – 2×2 array – operating

So far, I’ve had two people tell me they don’t know what it is, but they want one:

Glass Tile - various versions — Glass Tile – various versions

The OpenSCAD Customizer lets you set the array size:

Glass Tile Frame - 3x3 - press-fit SK6812 LEDs — Glass Tile Frame – 3×3 – press-fit SK6812 LEDs

However, just because you can do something doesn’t mean you should:

Glass Tile Frame - 6x6 cell array - openscad — Glass Tile Frame – 6×6 cell array – openscad

Something like this might be interesting:

Glass Tile Frame - 2x6 cell array - openscad — Glass Tile Frame – 2×6 cell array – openscad

In round numbers, printing the frame takes about an hour per cell, so a 2×2 array takes three hours and 3×3 array runs around seven hours. A 6×6 frame is just not happening.

The OpenSCAD source code as a GitHub Gist:

	// Illuminated Tile Grid
	// Ed Nisley – KE4ZNU
	// 2020-05

	/* [Configuration] */

	Layout = "Build"; // [Cell,CellArray,MCU,Base,Show,Build]

	Shape = "Square"; // [Square, Pyramid, Cone]

	Cells = [2,2];

	CellDepth = 15.0;

	Inserts = true;

	SupportInserts = true;

	/* [Hidden] */

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

	function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

	Protrusion = 0.1; // make holes end cleanly

	ID = 0;
	OD = 1;
	LENGTH = 2;

	Tile = [25.0 + 0.1,25.0 + 0.1,4.0];

	WallThick = 4*ThreadWidth;
	FloorThick = 3.0;

	Flange = [2ThreadWidth,2ThreadWidth,0]; // ridge supporting tile

	Separator = [3ThreadWidth,3ThreadWidth,Tile.z – 1]; // between tiles

	Screw = [3.0,6.0,3.5]; // M3 SHCS, OD=head, LENGTH=head
	Insert = [3.0,4.2,8.0]; // threaded brass insert

	ScrewRecess = Screw[LENGTH] + 4*ThreadThick;

	LEDPCB = [9.6,9.6,2.9]; // round SK6812, squared-off sides

	LED = [5.0 + 2HoleWindage,5.0 + 2HoleWindage,1.3];

	LEDOffset = [0.0,0.0,0.0]; // if offset from PCB center

	CellOAL = [Tile.x,Tile.y,0] + Separator + [0,0,CellDepth] + [0,0,FloorThick];

	ArrayOAL = [Cells.xCellOAL.x,Cells.yCellOAL.y,CellOAL.z]; // just the LED cells

	BlockOAL = ArrayOAL + [2WallThick,2WallThick,0]; // LED cells + exterior wall
	echo(str("Block OAL: ",BlockOAL));

	InsertOC = ArrayOAL – [Insert[OD],Insert[OD],0] – [WallThick,WallThick,0];
	echo(str("Insert OC: ",InsertOC));

	TapeThick = 1.0;

	Arduino = [44.0,18.0,8.0 + TapeThick]; // Arduino Nano to top of USB Mini-B plug
	USBPlug = [15.0,11.0,9.0]; // USB Mini-B plug insulator
	USBOffset = [0,0,5.0]; // offset from PCB base

	WiringSpace = 3.5;
	WiringBay = [(Cells.x – 1)CellOAL.x + LEDPCB.x,(Cells.y – 1)CellOAL.y + LEDPCB.x,WiringSpace];

	PlateOAL = [BlockOAL.x,BlockOAL.y,FloorThick + Arduino.z + WiringSpace]; // allow wiring above Arduino
	echo(str("Base Plate: ",PlateOAL));

	echo(str("Screw length: ",(PlateOAL.z – ScrewRecess) + Insert.z/2," to ",(PlateOAL.z – ScrewRecess) + Insert.z));

	LegendRecess = 1*ThreadThick;

	//————————

	module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes
	Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
	FixDia = Dia / cos(180/Sides);
	cylinder(d=(FixDia + HoleWindage),h=Height,$fn=Sides);
	}


	//———————–
	// Base and optics in single tile

	module LEDCone() {

	hull() {
	translate([0,0,CellDepth + Tile.z/2])
	cube(Tile – 2*[Flange.x,Flange.y,0],center=true);

	if (Shape == "Square") {
	translate([0,0,LEDPCB.z/2])
	cube([Tile.x,Tile.y,LEDPCB.z] – 2*[Flange.x,Flange.y,0],center=true);
	}
	else if (Shape == "Pyramid") {
	translate([0,0,LEDPCB.z/2])
	cube(LEDPCB,center=true);
	}
	else if (Shape == "Cone") {
	translate([0,0,LEDPCB.z/2])
	cylinder(d=1.0*LEDPCB.x,h=LED.z,center=true);
	}
	else {
	echo(str("Whoopsie! Invalid Shape: ",Shape));
	cube(5);
	}
	}
	}

	// One complete LED cell

	module LEDCell() {

	difference() {

	translate([0,0,CellOAL.z/2])
	cube(CellOAL + [Protrusion,Protrusion,0],center=true); // force overlapping adjacent sides!

	translate([0,0,CellOAL.z – Separator.z + Tile.z/2])
	cube(Tile,center=true);

	translate([0,0,LEDPCB.z])
	LEDCone();

	// cube([LED.x,LED.y,CellOAL.z],center=true);

	translate(-LEDOffset + [0,0,-CellOAL.z/2])
	rotate(180/8)
	PolyCyl(LEDPCB.x,CellOAL.z,8);
	}

	}

	// The whole array of cells

	module CellArray() {
	difference() {
	union() {
	translate([CellOAL.x/2 – Cells.xCellOAL.x/2,CellOAL.y/2 – Cells.yCellOAL.y/2,0])
	for (i=[0:Cells.x – 1], j=[0:Cells.y – 1])
	translate([iCellOAL.x,jCellOAL.y,0])
	LEDCell();
	if (Inserts) // bosses
	for (i=[-1,1], j=[-1,1])
	translate([iInsertOC.x/2,jInsertOC.y/2,0])
	rotate(180/8)
	cylinder(d=Insert[OD] + 2*WallThick,h=Insert[LENGTH],$fn=8);
	}
	if (Inserts) // holes
	for (i=[-1,1], j=[-1,1])
	translate([iInsertOC.x/2,jInsertOC.y/2,-Protrusion])
	rotate(180/8)
	PolyCyl(Insert[OD],Insert[LENGTH] + FloorThick + Protrusion,8);

	}

	difference() {
	translate([0,0,CellOAL.z/2])
	cube(BlockOAL,center=true);
	translate([0,0,CellOAL.z])
	cube(ArrayOAL + [0,0,2*CellOAL.z],center=true);

	}
	}

	// Arduino bounding box
	// Origin at center bottom of PCB

	module Controller() {
	union() {
	translate([0,0,Arduino.z/2])
	cube(Arduino,center=true);
	translate([Arduino.x/2 – Protrusion,-USBPlug.y/2,USBOffset.z + TapeThick – USBPlug.z/2])
	cube(USBPlug + [Protrusion,0,0],center=false);
	}
	}

	// Baseplate

	module BasePlate() {

	difference() {
	translate([0,0,PlateOAL.z/2])
	cube(PlateOAL,center=true);

	translate([PlateOAL.x/2 – Arduino.x/2 – 2*WallThick,0,FloorThick])
	Controller();

	translate([PlateOAL.x/2 – Arduino.x/2 – 2*WallThick,0,FloorThick + PlateOAL.z/2])
	cube([Arduino.x – 2*2.0,WiringBay.y,PlateOAL.z],center=true); // cutouts beside MCU

	translate([0,0,PlateOAL.z – WiringBay.z + PlateOAL.z/2 – Protrusion])
	cube([PlateOAL.x – 2*WallThick,WiringBay.y,PlateOAL.z],center=true); // cutout above MCU
	translate([0,0,PlateOAL.z – WiringBay.z + PlateOAL.z/2 – Protrusion])
	cube([WiringBay.x,PlateOAL.y – 2*WallThick,PlateOAL.z],center=true); // cutout above MCU


	if (Inserts)
	for (i=[-1,1], j=[-1,1])
	translate([iInsertOC.x/2,jInsertOC.y/2,-Protrusion])
	rotate(180/8) {
	PolyCyl(Screw[ID],2*PlateOAL.z,8);
	PolyCyl(Screw[OD],ScrewRecess + Protrusion,8);
	}

	cube([45,17.0,2*LegendRecess],center=true);
	}

	linear_extrude(height=2*LegendRecess) {
	translate([0,1])
	rotate(-0*90) mirror([1,0,0])
	text(text="Ed Nisley",size=6,font="Arial:style:Bold",halign="center");
	translate([0,-6.5])
	rotate(-0*90) mirror([1,0,0])
	text(text="softsolder.com",size=4.5,font="Arial:style:Bold",halign="center");
	}

	Fin = [Screw[OD]/2 – 1.5ThreadWidth,2ThreadWidth,ScrewRecess – ThreadThick];
	if (Inserts && SupportInserts)
	color("Yellow")
	for (i=[-1,1], j=[-1,1])
	translate([iInsertOC.x/2,jInsertOC.y/2,0]) {
	rotate(180/8)
	cylinder(d=6*ThreadWidth,h=ThreadThick,$fn=8);
	for (a=[0:90:360])
	rotate(a)
	translate([Fin.x/2 + ThreadWidth/2,0,(ScrewRecess – ThreadThick)/2])
	cube(Fin,center=true);
	}
	}


	//———————–
	// Build things

	if (Layout == "Cell")
	LEDCell();

	else if (Layout == "CellArray")
	CellArray();

	else if (Layout == "MCU")
	Controller();

	else if (Layout == "Base")
	BasePlate();

	else if (Layout == "Show") {
	translate([0,0,3*PlateOAL.z])
	CellArray();
	BasePlate();
	translate([PlateOAL.x/2 – Arduino.x/2 – 2*WallThick,0,FloorThick])
	color("Orange",0.3)
	Controller();
	}

	else if (Layout == "Build") union() {
	translate([0,0.6*BlockOAL.y,0])
	CellArray();
	translate([0,-0.6*BlockOAL.x,0])
	rotate(90)
	BasePlate();
	}

view raw Glass Tile Frame.scad hosted with ❤ by GitHub

2020-06-11

Glass Tiles: Glow vs. Flash Firmware

Although it’s not obvious in a still picture, the firmware now supports both the continuously changing colors of the Nissan fog lamp (mashed with tweaks from the vacuum tube lights) and the randomly changing colors from the LED matrix, both using SK6812 LEDs rather than the failing WS2812 modules:

Glass Tile - glow vs flash — Glass Tile – glow vs flash

Flash is a misnomer, as the tiles simply change from one color to the next, but I’ve never been adept at picking catchy names. In any event, the glass tiles on the left show nice pastel shades, in contrast to the bright primary(-ish) colors appearing on the right.

The colors are random numbers from 1 to 7, because 0 produces a somewhat ugly dark cell. The SK6812 modules have a white LED in addition to the RGB LEDs in the WS2812 modules, so I replace the “additive white” R+G+B color with the more-or-less true white (warm, for these modules) LED.

The new color goes into a cell picked at random (0 through 3, for 2×2 frames), except if the cell already holds the same color, whereupon a simple XOR flips the colors, except if the cell is already full-on white, whereupon it becomes half-on white to avoid going completely dark.

The glass tiles must change colors at a much slower pace than the 8×8 LED matrix, because there are so few cells; a random delay between 500 ms and 6 s seems about right.

They look really great in a dim room!

The Arduino source code as a GitHub Gist:

	// Neopixel lighting for glass tiles
	// Ed Nisley – KE4ANU – May 2020

	#include <Adafruit_NeoPixel.h>
	#include <Entropy.h>

	//———-
	// Pin assignments

	const byte PIN_NEO = A3; // DO – data to first Neopixel
	const byte PIN_MODE = 2; // DI – select mode
	const byte PIN_SPEED = 3; // DI – select speed
	const byte PIN_SELECT = 4; // DO – drive adjacent pins low

	const byte PIN_HEARTBEAT = 13; // DO – Arduino LED

	//———-
	// Constants

	// number of pixels
	#define PIXELS 9

	// lag between adjacent pixels in degrees of slowest period
	#define PIXELPHASE 45

	// update LEDs only this many ms apart (minus loop() overhead)
	#define UPDATEINTERVAL 50ul

	// number of steps per cycle, before applying prime factors
	#define RESOLUTION 500

	//———-
	// Globals

	// instantiate the Neopixel buffer array

	Adafruit_NeoPixel strip = Adafruit_NeoPixel(PIXELS, PIN_NEO, NEO_GRBW + NEO_KHZ800);

	struct pixcolor_t {
	unsigned int Prime;
	unsigned int NumSteps;
	unsigned int Step;
	float StepSize;
	float Phase;
	byte MaxPWM;
	};

	unsigned int PlatterSteps;

	byte PrimeList[] = {3,5,7,13,19,29};

	unsigned int MaxTileTime;

	// colors in each LED
	enum pixcolors {RED, GREEN, BLUE, WHITE, PIXELSIZE};

	struct pixcolor_t Pixels[PIXELSIZE]; // all the data for each pixel color intensity

	uint32_t UniColor;

	enum dispmode {GLOW, FLASH}; // based on input pin

	unsigned long UpdateMS;

	unsigned long MillisNow;
	unsigned long MillisThen;

	//– Select three unique primes for the color generator function
	// Then compute all the step parameters based on those values

	void SetColorGenerators(void) {

	Pixels[RED].Prime = PrimeList[random(sizeof(PrimeList))];

	do {
	Pixels[GREEN].Prime = PrimeList[random(sizeof(PrimeList))];
	} while (Pixels[RED].Prime == Pixels[GREEN].Prime);

	do {
	Pixels[BLUE].Prime = PrimeList[random(sizeof(PrimeList))];
	} while (Pixels[BLUE].Prime == Pixels[RED].Prime \|\|
	Pixels[BLUE].Prime == Pixels[GREEN].Prime);

	do {
	Pixels[WHITE].Prime = PrimeList[random(sizeof(PrimeList))];
	} while (Pixels[WHITE].Prime == Pixels[RED].Prime \|\|
	Pixels[WHITE].Prime == Pixels[GREEN].Prime \|\|
	Pixels[WHITE].Prime == Pixels[BLUE].Prime);

	if (!digitalRead(PIN_SPEED)) { // force fast for debugging
	Pixels[RED].Prime = 3;
	Pixels[GREEN].Prime = 5;
	Pixels[BLUE].Prime = 7;
	Pixels[WHITE].Prime = 11;
	}

	printf("Primes: %d %d %d %d\r\n",Pixels[RED].Prime,Pixels[GREEN].Prime,Pixels[BLUE].Prime,Pixels[WHITE].Prime);

	Pixels[RED].MaxPWM = 255;
	Pixels[GREEN].MaxPWM = 255;
	Pixels[BLUE].MaxPWM = 255;
	Pixels[WHITE].MaxPWM = 255;

	unsigned int PhaseSteps = (unsigned int) ((PIXELPHASE / 360.0) *
	RESOLUTION * (unsigned int) max(max(Pixels[RED].Prime,Pixels[GREEN].Prime),Pixels[BLUE].Prime));
	printf("Pixel phase offset: %d deg = %d steps\r\n",(int)PIXELPHASE,PhaseSteps);


	for (byte c=0; c < PIXELSIZE; c++) {
	Pixels[c].NumSteps = RESOLUTION * Pixels[c].Prime; // steps per cycle
	Pixels[c].StepSize = TWO_PI / Pixels[c].NumSteps; // radians per step
	Pixels[c].Step = random(Pixels[c].NumSteps); // current step
	Pixels[c].Phase = PhaseSteps * Pixels[c].StepSize;; // phase in radians for this color

	printf(" c: %d Steps: %5d Init: %5d Phase: %3d deg",c,Pixels[c].NumSteps,Pixels[c].Step,(int)(Pixels[c].Phase * 360.0 / TWO_PI));
	printf(" PWM: %d\r\n",Pixels[c].MaxPWM);
	}
	}

	//– Helper routine for printf()

	int s_putc(char c, FILE *t) {
	Serial.write(c);
	}

	//——————
	// Set the mood

	void setup() {

	pinMode(PIN_HEARTBEAT,OUTPUT);
	digitalWrite(PIN_HEARTBEAT,LOW); // show we arrived

	pinMode(PIN_MODE,INPUT_PULLUP);
	pinMode(PIN_SPEED,INPUT_PULLUP);

	pinMode(PIN_SELECT,OUTPUT);
	digitalWrite(PIN_SELECT,LOW); // drive adjacent pins

	Serial.begin(57600);
	fdevopen(&s_putc,0); // set up serial output for printf()

	printf("\r\nAlgorithmic Art Light – Glass Tiles\r\nEd Nisley – KE4ZNU – May 2020\r\n");

	printf("Display mode: %s\r\n",digitalRead(PIN_MODE) == GLOW ? "Glow" : "Flash");
	printf("Speed: %s\r\n",digitalRead(PIN_SPEED) ? "Normal" : "Override");

	Entropy.initialize(); // start up entropy collector

	// set up pixels

	strip.begin();
	strip.show();

	// lamp test

	printf("Lamp test: flash full-on colors\r\n");

	uint32_t FullRGBW = strip.Color(255,255,255,255);
	uint32_t FullRGB = strip.Color(255,255,255,0);
	uint32_t FullR = strip.Color(255,0,0,0);
	uint32_t FullG = strip.Color(0,255,0,0);
	uint32_t FullB = strip.Color(0,0,255,0);
	uint32_t FullW = strip.Color(0,0,0,255);
	uint32_t FullOff = strip.Color(0,0,0,0);

	uint32_t TestColors[] = {FullR,FullG,FullB,FullRGB,FullW,FullRGBW,FullOff};

	for (byte i=0; i < sizeof(TestColors)/sizeof(uint32_t) ; i++) {
	printf(" color: %08lx\r\n",TestColors[i]);
	for (int j=0; j < strip.numPixels(); j++) {
	strip.setPixelColor(j,TestColors[i]);
	}
	strip.show();
	delay(1000);
	}

	// while (1) {continue;}; // all LEDs constant for burn-in testing

	// get an actual random number

	uint32_t rn = Entropy.random();

	printf("Random seed: %08lx\r\n",rn);
	randomSeed(rn);

	// set up the color generators

	SetColorGenerators();

	MaxTileTime = (digitalRead(PIN_SPEED) ? 6 : 1) * (1000.0 / UPDATEINTERVAL);

	UpdateMS = UPDATEINTERVAL;

	MillisNow = MillisThen = millis();

	}

	//——————
	// Run the mood

	void loop() {

	MillisNow = millis();
	if ((MillisNow – MillisThen) >= UpdateMS) { // time for color change?

	digitalWrite(PIN_HEARTBEAT,HIGH);

	if (digitalRead(PIN_MODE) == GLOW) {

	boolean CycleRun = false; // check to see if all cycles have ended
	for (byte c=0; c < PIXELSIZE; c++) { // compute next increment for each color
	if (++Pixels[c].Step >= Pixels[c].NumSteps) {
	Pixels[c].Step = 0;
	printf("Cycle %5d steps %5d at %8ld delta %8ld ms\r\n",c,Pixels[c].NumSteps,MillisNow,(MillisNow – MillisThen));
	}
	else {
	CycleRun = true; // this color is still cycling
	}
	}

	if (!CycleRun) {
	printf("All cycles ended: setting new color generator values\r\n");
	SetColorGenerators();
	}

	for (int i=0; i < strip.numPixels(); i++) { // for each pixel
	byte Value[PIXELSIZE];
	for (byte c=0; c < PIXELSIZE; c++) { // … for each color
	Value[c] = (Pixels[c].MaxPWM / 2.0) * (1.0 + sin(Pixels[c].Step * Pixels[c].StepSize – i*Pixels[c].Phase));
	}

	byte WhiteBias = min(min(Value[RED],Value[GREEN]),Value[BLUE]); // hack to reduce power
	UniColor = strip.Color((Value[RED] – WhiteBias) * Pixels[RED].MaxPWM/255,
	(Value[GREEN] – WhiteBias) * Pixels[GREEN].MaxPWM/255,
	(Value[BLUE] – WhiteBias) * Pixels[BLUE].MaxPWM/255,
	WhiteBias * Pixels[WHITE].MaxPWM/255);

	strip.setPixelColor(i,UniColor);
	}
	}

	else {

	byte c = random(1,8); // exclude 0 = all off, to avoid darkness
	printf("Color %d ",c);

	byte r = c & 0x04 ? 0xff : 0;
	byte g = c & 0x02 ? 0xff : 0;
	byte b = c & 0x01 ? 0xff : 0;
	byte w = 0;

	if (c == 7) { // use white LED instead of R+G+B
	r = g = b = 0;
	w = 0xff;
	}

	UniColor = strip.Color(r, g, b, w);

	byte i = random(strip.numPixels());
	printf("at %d ",i);

	if (UniColor == strip.getPixelColor(i)) { // flip color
	printf("^ ");
	if (w) { // white becomes dim
	w = 0x7f;
	UniColor = strip.Color(r, g, b, w);
	}
	else
	UniColor ^= 0xffffff00l; // other colors flip
	}
	else {
	printf(" ");
	}

	strip.setPixelColor(i,UniColor);

	UpdateMS = random(10,MaxTileTime) * UPDATEINTERVAL; // pick time for next update
	printf("delay: %6ld ms\r\n",UpdateMS);
	}

	strip.show(); // send out precomputed colors

	MillisThen = MillisNow;
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	}

view raw GlassTiles.ino hosted with ❤ by GitHub

2020-06-10

More WS2812 Failures

Even though I’m using what seem to be good-quality parts, one of the WS2812 RGB LEDs in a Glass Tile frame died:

Glass Tile – 2×2 – first WS2812B failure

It passed the Josh Sharpie Test:

Glass Tile – WS2812 failure – PCB unknown

After building the third Glass Tile unit, one of the LEDs didn’t light up due to an easily diagnosed problem:

Glass Tile – WS2812 failure – PCB cold solder – as found

A closer look:

Glass Tile – WS2812 failure – PCB cold solder

Shortly thereafter, the Nissan Fog Lamp developed an obvious beam problem:

Nissan Fog Lamp – failed WS2812 effect

The WS2812 had the proper voltages / signals at all its pins and was still firmly stuck to the central “heatsink”:

Nissan Fog Lamp – failed WS2812 detail

It also passed the Josh Sharpie Test:

Glass Tile – WS2812 failure – tape – unknown

I’m particularly surprised by this one, because eleven of the twelve flex-PCB WS2812s in the Hard Drive Platter light have been running continuously for years with no additional failures.

The alert reader will note the common factor: no matter what substrate the LED is (supposed to be) soldered to, no matter when I bought it, no matter what it’s wired into, a WS2812 will fail.

They’re all back in operation:

Glowing Algorithmic Art

Although nobody knows for how long …

Obviously, it’s time to refresh my programmable RGB LED stockpile!

2020-06-04