✨ ESP32 - Hardware PWM for fan, cutter, servos (MarlinFirmware#23802)

Author: HoverClub

Marlin/Configuration_adv.h

@@ -3464,7 +3464,7 @@
   #define SPINDLE_LASER_USE_PWM                // Enable if your controller supports setting the speed/power
   #if ENABLED(SPINDLE_LASER_USE_PWM)
     #define SPINDLE_LASER_PWM_INVERT    false  // Set to "true" if the speed/power goes up when you want it to go slower
-    #define SPINDLE_LASER_FREQUENCY     2500   // (Hz) Spindle/laser frequency (only on supported HALs: AVR and LPC)
+    #define SPINDLE_LASER_FREQUENCY     2500   // (Hz) Spindle/laser frequency (only on supported HALs: AVR, ESP32 and LPC)
   #endif
 
   //#define AIR_EVACUATION                     // Cutter Vacuum / Laser Blower motor control with G-codes M10-M11

Marlin/src/HAL/ESP32/HAL.cpp

@@ -73,9 +73,16 @@ uint16_t MarlinHAL::adc_result;
 esp_adc_cal_characteristics_t characteristics[ADC_ATTEN_MAX];
 adc_atten_t attenuations[ADC1_CHANNEL_MAX] = {};
 uint32_t thresholds[ADC_ATTEN_MAX];
-volatile int numPWMUsed = 0,
-             pwmPins[MAX_PWM_PINS],
-             pwmValues[MAX_PWM_PINS];
+
+volatile int numPWMUsed = 0;
+volatile struct { pin_t pin; int value; } pwmState[MAX_PWM_PINS];
+
+pin_t chan_pin[CHANNEL_MAX_NUM + 1] = { 0 }; // PWM capable IOpins - not 0 or >33 on ESP32
+
+struct {
+  uint32_t freq; // ledcReadFreq doesn't work if a duty hasn't been set yet!
+  uint16_t res;
+} pwmInfo[(CHANNEL_MAX_NUM + 1) / 2];
 
 // ------------------------
 // Public functions
@@ -254,25 +261,81 @@ void MarlinHAL::adc_start(const pin_t pin) {
   adc1_set_attenuation(chan, atten);
 }
 
-void analogWrite(pin_t pin, int value) {
-  // Use ledc hardware for internal pins
-  if (pin < 34) {
-    static int cnt_channel = 1, pin_to_channel[40] = { 0 };
-    if (pin_to_channel[pin] == 0) {
-      ledcAttachPin(pin, cnt_channel);
-      ledcSetup(cnt_channel, 490, 8);
-      ledcWrite(cnt_channel, value);
-      pin_to_channel[pin] = cnt_channel++;
+// ------------------------
+// PWM
+// ------------------------
+
+int8_t channel_for_pin(const uint8_t pin) {
+  for (int i = 0; i <= CHANNEL_MAX_NUM; i++)
+    if (chan_pin[i] == pin) return i;
+  return -1;
+}
+
+// get PWM channel for pin - if none then attach a new one
+// return -1 if fail or invalid pin#, channel # (0-15) if success
+int8_t get_pwm_channel(const pin_t pin, const uint32_t freq, const uint16_t res) {
+  if (!WITHIN(pin, 1, MAX_PWM_IOPIN)) return -1; // Not a hardware PWM pin!
+  int8_t cid = channel_for_pin(pin);
+  if (cid >= 0) return cid;
+
+  // Find an empty adjacent channel (same timer & freq/res)
+  for (int i = 0; i <= CHANNEL_MAX_NUM; i++) {
+    if (chan_pin[i] == 0) {
+      if (chan_pin[i ^ 0x1] != 0) {
+        if (pwmInfo[i / 2].freq == freq && pwmInfo[i / 2].res == res) {
+          chan_pin[i] = pin; // Allocate PWM to this channel
+          ledcAttachPin(pin, i);
+          return i;
+        }
+      }
+      else if (cid == -1)    // Pair of empty channels?
+        cid = i & 0xFE;      // Save lower channel number
     }
-    ledcWrite(pin_to_channel[pin], value);
+  }
+  // not attached, is an empty timer slot avail?
+  if (cid >= 0) {
+    chan_pin[cid] = pin;
+    pwmInfo[cid / 2].freq = freq;
+    pwmInfo[cid / 2].res = res;
+    ledcSetup(cid, freq, res);
+    ledcAttachPin(pin, cid);
+  }
+  return cid; // -1 if no channel avail
+}
+
+void MarlinHAL::set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t v_size/*=_BV(PWM_RESOLUTION)-1*/, const bool invert/*=false*/) {
+  const int8_t cid = get_pwm_channel(pin, PWM_FREQUENCY, PWM_RESOLUTION);
+  if (cid >= 0) {
+    uint32_t duty = map(invert ? v_size - v : v, 0, v_size, 0, _BV(PWM_RESOLUTION)-1);
+    ledcWrite(cid, duty);
+  }
+}
+
+int8_t MarlinHAL::set_pwm_frequency(const pin_t pin, const uint32_t f_desired) {
+  const int8_t cid = channel_for_pin(pin);
+  if (cid >= 0) {
+    if (f_desired == ledcReadFreq(cid)) return cid; // no freq change
+    ledcDetachPin(chan_pin[cid]);
+    chan_pin[cid] = 0;              // remove old freq channel
+  }
+  return get_pwm_channel(pin, f_desired, PWM_RESOLUTION); // try for new one
+}
+
+// use hardware PWM if avail, if not then ISR
+void analogWrite(const pin_t pin, const uint16_t value, const uint32_t freq/*=PWM_FREQUENCY*/, const uint16_t res/*=8*/) { // always 8 bit resolution!
+  // Use ledc hardware for internal pins
+  const int8_t cid = get_pwm_channel(pin, freq, res);
+  if (cid >= 0) {
+    ledcWrite(cid, value); // set duty value
     return;
   }
 
+  // not a hardware PWM pin OR no PWM channels available
   int idx = -1;
 
   // Search Pin
   for (int i = 0; i < numPWMUsed; ++i)
-    if (pwmPins[i] == pin) { idx = i; break; }
+    if (pwmState[i].pin == pin) { idx = i; break; }
 
   // not found ?
   if (idx < 0) {
@@ -281,15 +344,15 @@ void analogWrite(pin_t pin, int value) {
 
     // Take new slot for pin
     idx = numPWMUsed;
-    pwmPins[idx] = pin;
+    pwmState[idx].pin = pin;
     // Start timer on first use
     if (idx == 0) HAL_timer_start(MF_TIMER_PWM, PWM_TIMER_FREQUENCY);
 
     ++numPWMUsed;
   }
 
   // Use 7bit internal value - add 1 to have 100% high at 255
-  pwmValues[idx] = (value + 1) / 2;
+  pwmState[idx].value = (value + 1) / 2;
 }
 
 // Handle PWM timer interrupt
@@ -300,9 +363,9 @@ HAL_PWM_TIMER_ISR() {
 
   for (int i = 0; i < numPWMUsed; ++i) {
     if (count == 0)                   // Start of interval
-      WRITE(pwmPins[i], pwmValues[i] ? HIGH : LOW);
-    else if (pwmValues[i] == count)   // End of duration
-      WRITE(pwmPins[i], LOW);
+      digitalWrite(pwmState[i].pin, pwmState[i].value ? HIGH : LOW);
+    else if (pwmState[i].value == count)   // End of duration
+      digitalWrite(pwmState[i].pin, LOW);
   }
 
   // 128 for 7 Bit resolution

Marlin/src/HAL/ESP32/HAL.h

@@ -64,6 +64,12 @@
 #define CRITICAL_SECTION_START() portENTER_CRITICAL(&spinlock)
 #define CRITICAL_SECTION_END()   portEXIT_CRITICAL(&spinlock)
 
+#define HAL_CAN_SET_PWM_FREQ   // This HAL supports PWM Frequency adjustment
+#define PWM_FREQUENCY  1000u   // Default PWM frequency when set_pwm_duty() is called without set_pwm_frequency()
+#define PWM_RESOLUTION   10u   // Default PWM bit resolution
+#define CHANNEL_MAX_NUM  15u   // max PWM channel # to allocate (7 to only use low speed, 15 to use low & high)
+#define MAX_PWM_IOPIN    33u   // hardware pwm pins < 34
+
 // ------------------------
 // Types
 // ------------------------
@@ -83,7 +89,7 @@ typedef Servo hal_servo_t;
 void tone(const pin_t _pin, const unsigned int frequency, const unsigned long duration=0);
 void noTone(const pin_t _pin);
 
-void analogWrite(pin_t pin, int value);
+void analogWrite(const pin_t pin, const uint16_t value, const uint32_t freq=PWM_FREQUENCY, const uint16_t res=8);
 
 //
 // Pin Mapping for M42, M43, M226
@@ -209,12 +215,17 @@ class MarlinHAL {
   static uint16_t adc_value() { return adc_result; }
 
   /**
-   * Set the PWM duty cycle for the pin to the given value.
-   * No inverting the duty cycle in this HAL.
-   * No changing the maximum size of the provided value to enable finer PWM duty control in this HAL.
+   * If not already allocated, allocate a hardware PWM channel
+   * to the pin and set the duty cycle..
+   * Optionally invert the duty cycle [default = false]
+   * Optionally change the scale of the provided value to enable finer PWM duty control [default = 255]
    */
-  static void set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t=255, const bool=false) {
-    analogWrite(pin, v);
-  }
+  static void set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t v_size=255, const bool invert=false);
+
+  /**
+   * Allocate and set the frequency of a hardware PWM pin
+   * Returns -1 if no pin available.
+   */
+  static int8_t set_pwm_frequency(const pin_t pin, const uint32_t f_desired);
 
 };

Marlin/src/HAL/ESP32/Servo.cpp

@@ -31,28 +31,26 @@
 // so we only allocate servo channels up high to avoid side effects with regards to analogWrite (fans, leds, laser pwm etc.)
 int Servo::channel_next_free = 12;
 
-Servo::Servo() {
-  channel = channel_next_free++;
-}
+Servo::Servo() {}
 
 int8_t Servo::attach(const int inPin) {
-  if (channel >= CHANNEL_MAX_NUM) return -1;
   if (inPin > 0) pin = inPin;
-
-  ledcSetup(channel, 50, 16); // channel X, 50 Hz, 16-bit depth
-  ledcAttachPin(pin, channel);
-  return true;
+  channel = get_pwm_channel(pin, 50u, 16u);
+  return channel; // -1 if no PWM avail.
 }
 
-void Servo::detach() { ledcDetachPin(pin); }
+// leave channel connected to servo - set duty to zero
+void Servo::detach() {
+  if (channel >= 0) ledcWrite(channel, 0);
+}
 
 int Servo::read() { return degrees; }
 
 void Servo::write(int inDegrees) {
   degrees = constrain(inDegrees, MIN_ANGLE, MAX_ANGLE);
   int us = map(degrees, MIN_ANGLE, MAX_ANGLE, MIN_PULSE_WIDTH, MAX_PULSE_WIDTH);
   int duty = map(us, 0, TAU_USEC, 0, MAX_COMPARE);
-  ledcWrite(channel, duty);
+  if (channel >= 0) ledcWrite(channel, duty); // don't save duty for servos!
 }
 
 void Servo::move(const int value) {

Marlin/src/HAL/ESP32/Servo.h

@@ -30,8 +30,7 @@ class Servo {
                    MAX_PULSE_WIDTH = 2400,  // Longest pulse sent to a servo
                    TAU_MSEC = 20,
                    TAU_USEC = (TAU_MSEC * 1000),
-                   MAX_COMPARE = _BV(16) - 1, // 65535
-                   CHANNEL_MAX_NUM = 16;
+                   MAX_COMPARE = _BV(16) - 1; // 65535
 
 public:
   Servo();

Marlin/src/HAL/ESP32/inc/SanityCheck.h

@@ -25,8 +25,8 @@
   #error "EMERGENCY_PARSER is not yet implemented for ESP32. Disable EMERGENCY_PARSER to continue."
 #endif
 
-#if ENABLED(FAST_PWM_FAN) || SPINDLE_LASER_FREQUENCY
-  #error "Features requiring Hardware PWM (FAST_PWM_FAN, SPINDLE_LASER_FREQUENCY) are not yet supported on ESP32."
+#if (ENABLED(SPINDLE_LASER_USE_PWM) && SPINDLE_LASER_FREQUENCY > 78125) || (ENABLED(FAST_PWM_FAN_FREQUENCY) && FAST_PWM_FAN_FREQUENCY > 78125)
+  #error "SPINDLE_LASER_FREQUENCY and FAST_PWM_FREQUENCY maximum value is 78125Hz for ESP32."
 #endif
 
 #if HAS_TMC_SW_SERIAL
@@ -40,3 +40,7 @@
 #if ENABLED(POSTMORTEM_DEBUGGING)
   #error "POSTMORTEM_DEBUGGING is not yet supported on ESP32."
 #endif
+
+#if MB(MKS_TINYBEE) && ENABLED(FAST_PWM_FAN)
+  #error "FAST_PWM_FAN is not available on TinyBee."
+#endif