let analogWrite coexist with open-drain mode

Author: dok-net

cores/esp8266/core_esp8266_wiring_digital.cpp

@@ -82,7 +82,7 @@ extern void __pinMode(uint8_t pin, uint8_t mode) {
 }
 
 extern void IRAM_ATTR __digitalWrite(uint8_t pin, uint8_t val) {
-  stopWaveform(pin); // Disable any Tone or startWaveform on this pin
+  stopWaveform(pin); // Disable any Tone, startWaveform, or analogWrite on this pin
   if(pin < 16){
     if(val) GPOS = (1 << pin);
     else GPOC = (1 << pin);

cores/esp8266/core_esp8266_wiring_pwm.cpp

@@ -44,7 +44,14 @@ extern void __analogWriteFreq(uint32_t freq) {
 }
 
 extern void __analogWrite(uint8_t pin, int val) {
-  analogWriteMode(pin, val, false);
+  if (pin > 16) {
+    return;
+  }
+  bool openDrain = false;
+  if (analogMap & 1UL << pin) {
+    openDrain = GPC(pin) & (1 << GPCD);
+  }
+  analogWriteMode(pin, val, openDrain);
 }
 
 extern void __analogWriteMode(uint8_t pin, int val, bool openDrain) {
@@ -59,23 +66,22 @@ extern void __analogWriteMode(uint8_t pin, int val, bool openDrain) {
   }
 
   if (analogMap & 1UL << pin) {
-  // Per the Arduino docs at https://www.arduino.cc/reference/en/language/functions/analog-io/analogwrite/
-  // val: the duty cycle: between 0 (always off) and 255 (always on).
-  // So if val = 0 we have digitalWrite(LOW), if we have val==range we have digitalWrite(HIGH)
-
     analogMap &= ~(1 << pin);
+    const bool isOpenDrain = GPC(pin) & (1 << GPCD);
+    if (isOpenDrain != openDrain) {
+      GPC(pin) ^= (1 << GPCD);
+    }
   }
   else {
-    if(openDrain) {
-      pinMode(pin, OUTPUT_OPEN_DRAIN);
-    } else {
-      pinMode(pin, OUTPUT);
-    }
+    pinMode(pin, openDrain ? OUTPUT_OPEN_DRAIN : OUTPUT);
   }
   uint32_t high = (analogPeriod * val) / analogScale;
   uint32_t low = analogPeriod - high;
   // Find the first GPIO being generated by checking GCC's find-first-set (returns 1 + the bit of the first 1 in an int32_t)
   int phaseReference = __builtin_ffs(analogMap) - 1;
+  // Per the Arduino docs at https://www.arduino.cc/reference/en/language/functions/analog-io/analogwrite/
+  // val: the duty cycle: between 0 (always off) and 255 (always on).
+  // So if val = 0 we have digitalWrite(LOW), if we have val==range we have digitalWrite(HIGH)
   if (_setPWM(pin, val, analogScale)) {
     analogMap |= (1 << pin);
   } else if (startWaveformClockCycles(pin, high, low, 0, phaseReference, 0, true)) {

libraries/Servo/src/Servo.cpp

@@ -116,8 +116,7 @@ void Servo::writeMicroseconds(int value)
     _servoMap &= ~(1 << _pin);
     // Find the first GPIO being generated by checking GCC's find-first-set (returns 1 + the bit of the first 1 in an int32_t)
     int phaseReference = __builtin_ffs(_servoMap) - 1;
-    if (startWaveform(_pin, _valueUs, REFRESH_INTERVAL - _valueUs, 0, phaseReference))
-    {
+    if (startWaveform(_pin, _valueUs, REFRESH_INTERVAL - _valueUs, 0, phaseReference)) {
       _servoMap |= (1 << _pin);
     }
   }