diff --git a/cores/esp8266/core_esp8266_waveform.cpp b/cores/esp8266/core_esp8266_waveform.cpp
index 597a8e88ab..0338dbc952 100644
--- a/cores/esp8266/core_esp8266_waveform.cpp
+++ b/cores/esp8266/core_esp8266_waveform.cpp
@@ -170,6 +170,13 @@ static inline ICACHE_RAM_ATTR uint32_t min_u32(uint32_t a, uint32_t b) {
return b;
}
+static inline ICACHE_RAM_ATTR int32_t max_32(int32_t a, int32_t b) {
+ if (a < b) {
+ return b;
+ }
+ return a;
+}
+
// Stops a waveform on a pin
int ICACHE_RAM_ATTR stopWaveform(uint8_t pin) {
// Can't possibly need to stop anything if there is no timer active
@@ -259,6 +266,17 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
// Check for toggles
int32_t cyclesToGo = wave->nextServiceCycle - now;
if (cyclesToGo < 0) {
+ // See #7057
+ // The following is a no-op unless we have overshot by an entire waveform cycle.
+ // As modulus is an expensive operation, this code is removed for now:
+ // cyclesToGo = -((-cyclesToGo) % (wave->nextTimeHighCycles + wave->nextTimeLowCycles));
+ //
+ // Alternative version with lower CPU impact:
+ // while (-cyclesToGo > wave->nextTimeHighCycles + wave->nextTimeLowCycles) { cyclesToGo += wave->nextTimeHighCycles + wave->nextTimeLowCycles); }
+ //
+ // detect interrupt storm, for example during wifi connection.
+ // if we overshoot the cycle by more than 25%, we forget phase and keep PWM duration
+ int32_t overshoot = ((uint32_t)-cyclesToGo) > ((wave->nextTimeHighCycles + wave->nextTimeLowCycles) >> 2);
waveformState ^= mask;
if (waveformState & mask) {
if (i == 16) {
@@ -266,16 +284,26 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
} else {
SetGPIO(mask);
}
- wave->nextServiceCycle = now + wave->nextTimeHighCycles;
- nextEventCycles = min_u32(nextEventCycles, wave->nextTimeHighCycles);
+ if (overshoot) {
+ wave->nextServiceCycle = now + wave->nextTimeHighCycles;
+ nextEventCycles = min_u32(nextEventCycles, wave->nextTimeHighCycles);
+ } else {
+ wave->nextServiceCycle += wave->nextTimeHighCycles;
+ nextEventCycles = min_u32(nextEventCycles, max_32(wave->nextTimeHighCycles + cyclesToGo, microsecondsToClockCycles(1)));
+ }
} else {
if (i == 16) {
GP16O &= ~1; // GPIO16 write slow as it's RMW
} else {
ClearGPIO(mask);
}
- wave->nextServiceCycle = now + wave->nextTimeLowCycles;
- nextEventCycles = min_u32(nextEventCycles, wave->nextTimeLowCycles);
+ if (overshoot) {
+ wave->nextServiceCycle = now + wave->nextTimeLowCycles;
+ nextEventCycles = min_u32(nextEventCycles, wave->nextTimeLowCycles);
+ } else {
+ wave->nextServiceCycle += wave->nextTimeLowCycles;
+ nextEventCycles = min_u32(nextEventCycles, max_32(wave->nextTimeLowCycles + cyclesToGo, microsecondsToClockCycles(1)));
+ }
}
} else {
uint32_t deltaCycles = wave->nextServiceCycle - now;
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