Merge pull request #8094 from s-hadinger/pwm_flicker2

Fix PWM flickering during wifi connection (#8046)
arendst · Apr 8, 2020 · 8d97bcd · 8d97bcd
2 parents 8b7aca3 + 11746d9
commit 8d97bcd
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Showing 2 changed files with 20 additions and 5 deletions.
diff --git a/tasmota/CHANGELOG.md b/tasmota/CHANGELOG.md
@@ -14,6 +14,7 @@
 - Add command ``SetOption91 1`` to enable fading at startup / power on
 - Add command ``SetOption41 <x>`` to force sending gratuitous ARP every <x> seconds
 - Add quick wifi reconnect using saved AP parameters when ``SetOption56 0`` (#3189)
+- Fix PWM flickering during wifi connection (#8046)
 
 ### 8.2.0.2 20200328
 

diff --git a/tasmota/core_esp8266_waveform.cpp b/tasmota/core_esp8266_waveform.cpp
@@ -274,24 +274,38 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
           // cyclesToGo = -((-cyclesToGo) % (wave->nextTimeHighCycles + wave->nextTimeLowCycles));
           //
           // Alternative version with lower CPU impact:
-          // while (-cyclesToGo > wave->nextTimeHighCycles + wave->nextTimeLowCycles) { cyclesToGo += wave->nextTimeHighCycles + wave->nextTimeLowCycles)};
+          // 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 = (-cyclesToGo) > ((wave->nextTimeHighCycles + wave->nextTimeLowCycles) >> 2);
           waveformState ^= mask;
           if (waveformState & mask) {
             if (i == 16) {
               GP16O |= 1; // GPIO16 write slow as it's RMW
             } else {
               SetGPIO(mask);
             }
-            wave->nextServiceCycle += wave->nextTimeHighCycles;
-            nextEventCycles = min_u32(nextEventCycles, max_32(wave->nextTimeHighCycles + cyclesToGo, microsecondsToClockCycles(1)));
+            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 += wave->nextTimeLowCycles;
-            nextEventCycles = min_u32(nextEventCycles, max_32(wave->nextTimeLowCycles + cyclesToGo, microsecondsToClockCycles(1)));
+            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;