Sleepy TM1934

[ldalep]

I am having an issue with a TM1934 LED strip. It appears that the chip will reset after ~500ms. If I continue to issue refreshes to the strip all is fine. I am wondering if there is a work around with WS2812FX software? For example it appears that there is only a refresh on say Mode 0 static when there is >= what ever the speed is set. If I set the speed at ~100 I have no issues with this mode and others using the TM1934 strip. I noticed this to be true when I was changing static colors on ws2812 when going from DMX controllers. Simple there I just decreased the speed to 10.

[moose4lord]

WS2812FX inherits code from Adafruit_NeoPixel library, which technically only supports WS2812-style LEDs. The TM1934 driver chip is similar to a WS2812B, but has a weird reset command that resets the chip if the data line is held low for longer than 200us. Essentially the chip expects to the Din pin to constantly update the LEDs with data, regardless of wether the LED data changes or not. By contrast, WS2812 LEDs latch the data, so only need to be updated when the data changes.

So we'd need to feed data to the TM1934 at least every 200us, even if the LED data hasn't changed. I came up with this sketch:

#include <WS2812FX.h>

#define LED_PIN   14  // digital pin used to drive the LED strip
#define LED_COUNT 64  // number of LEDs on the strip

WS2812FX ws2812fx = WS2812FX(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

unsigned long showTimer = 0;

void setup() {
  Serial.begin(115200);

  ws2812fx.init();
  ws2812fx.setBrightness(8);

  // parameters: index, start, stop, mode, color, speed, reverse
  ws2812fx.setSegment(0,  0,  7, FX_MODE_BLINK, 0xFF0000, 1000, false); // segment 0 is leds 0 - 9
  ws2812fx.setSegment(1,  8, 15, FX_MODE_SCAN,  0x00FF00, 1000, false); // segment 1 is leds 10 - 19
  ws2812fx.setSegment(2, 16, LED_COUNT-1, FX_MODE_COMET, 0x0000FF, 1000, true);  // segment 2 is leds 20 - 29

  ws2812fx.start();
}

void loop() {
  unsigned long now = micros();

  ws2812fx.service();

  if(ws2812fx.isFrame()) {  // if just ran show() function, reset the show timer
    showTimer = now;
  }

  if(showTimer - now > 200) { // if greater than 200us since last show, execute show() function
    ws2812fx.execShow();
    showTimer = now;
  }
}

I don't have a TM1934 to test with, so it may work or it may not. It's a bit of a hack, but hopefully that points you in the right direction.

[ldalep]

Thank you for the quick reply. This works fine. The only thing was that I found that the "reset (where the chip shuts down)" was around 400000us ???? This is where I noted with my past experiences. Also I had to reverse the if statement to read

if( now - showTimer)

Thanks again for the help