Fix for going off 100% duty cycle period.

cores/esp8266/core_esp8266_waveform.cpp

@@ -260,38 +260,45 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
 	int32_t nextEventCcys = nextEventCcy - now;
 	if (nextEventCcys <= 0) {
  uint32_t skipPeriodCcys = (-nextEventCcys / wave->periodCcys) * wave->periodCcys;
+ bool flatLine = wave->nextPhaseCcy == wave->nextOffCcy;
  if (waveformsState & (1UL << pin)) {
- wave->nextPhaseCcy += wave->periodCcys + skipPeriodCcys;
- if (wave->dutyCcys != wave->periodCcys) {
+ if (wave->dutyCcys == wave->periodCcys) {
+ wave->nextPhaseCcy += wave->periodCcys + skipPeriodCcys;
+ wave->nextOffCcy = wave->nextPhaseCcy;
+ nextEventCcy = wave->nextPhaseCcy;
+ }
+ else if (flatLine) {
+ wave->nextOffCcy = wave->nextPhaseCcy + wave->dutyCcys + skipPeriodCcys;
+ wave->nextPhaseCcy += wave->periodCcys + skipPeriodCcys;
+ nextEventCcy = wave->nextOffCcy;
+ }
+ else {
  if (pin == 16) {
  GP16O &= ~1; // GPIO16 write slow as it's RMW
  }
  else {
  ClearGPIO(1UL << pin);
  }
  waveformsState ^= 1UL << pin;
+ nextEventCcy = wave->nextPhaseCcy;
  }
- else {
- wave->nextOffCcy = wave->nextPhaseCcy;
- }
- nextEventCcy = wave->nextPhaseCcy;
  }
  else {
- if (wave->dutyCcys) {
+ wave->nextOffCcy = wave->nextPhaseCcy + wave->dutyCcys + skipPeriodCcys;
+ if (!wave->dutyCcys) {
+ wave->nextPhaseCcy = wave->nextOffCcy;
+ }
+ else {
  if (pin == 16) {
  GP16O |= 1; // GPIO16 write slow as it's RMW
  }
  else {
  SetGPIO(1UL << pin);
  }
  waveformsState ^= 1UL << pin;
- wave->nextOffCcy = wave->nextPhaseCcy + wave->dutyCcys + skipPeriodCcys;
- nextEventCcy = wave->nextOffCcy;
- }
- else {
  wave->nextPhaseCcy += wave->periodCcys + skipPeriodCcys;
- nextEventCcy = wave->nextPhaseCcy;
  }
+ nextEventCcy = wave->nextOffCcy;
  }
  }
  }