ESP32: 200ms flicker every ~17.9 seconds with RMT driver #1329
Description
I discovered an issue that LEDs have short ~200ms flicker every ~17.9 seconds.
I investigated the problem and it turned out, the it has to do with __clock_cycles(). __clock_cycles() returns a 32bit value, each time the 32bit overrun occurs you see a short LED flicker at all LEDs which values change more then 10 times per second.
The sample project below blinks one LED very fast, if you watch the LED you will see the flickering every 17,9 seconds.
Could the problem be caused in the ESP32RMTController::fillNext method?
if (mLastFill != 0 and now > mLastFill) {
doesn't handle overrun correctly
Code sample for problem reproduction
#include <Arduino.h>
#define FASTLED_INTERNAL // Disable version number message in FastLED library (looks like an error)
#include <FastLED.h>
const unsigned NUM_OF_LEDS = 256;
CRGB leds[NUM_OF_LEDS];
TaskHandle_t FASTLedTaskHnd;
void setup() {
Serial.begin(921600);
//FastLED.addLeds<WS2812B, 27, EOrder::RBG>(leds, 0, NUM_OF_LEDS);
CLEDController& controller0 = FastLED.addLeds<NEOPIXEL, 27>(leds+ 0, NUM_OF_LEDS);
controller0.clearLeds(256);
FastLED.setDither(DISABLE_DITHER);
xTaskCreatePinnedToCore(FASTLedTask,"FASTLed",4096,NULL,1,&FASTLedTaskHnd,0);
}
void FASTLedTask( void * parameter ) {
//--------------------------------
while(1) {
yield();
loopFASTLed();
delay (1);
}
}
void loop()
{
}
auto lastSecond = millis()/1000;
void loopFASTLed()
{
auto timeBefore = millis();
leds[0].r = ((timeBefore/30)&0x01)*128;
FastLED.show();
auto passedTime = millis() - timeBefore;
if ((passedTime!=8&&passedTime!=7) || timeBefore/1000!=lastSecond)
{
lastSecond = timeBefore/1000;
Serial.print("millis=");
Serial.print(timeBefore);
Serial.print(" cycles=");
Serial.print(__clock_cycles());
Serial.print(" show() took ");
Serial.print(passedTime);
Serial.println(" ms");
}
}