Expand PWM support from 3 to 5 simultaneous channels

cores/gecko/pwm.cpp

@@ -41,13 +41,13 @@ PwmClass::PwmClass() :
     .polarity  = PWM_ACTIVE_HIGH,
   };
 
-  for (auto& pwm_pin : pwm_pins) {
-    pwm_pin.pin = PIN_NAME_MAX;
-    pwm_pin.inst.timer = TIMER0;
-    pwm_pin.inst.channel = 0;
-    pwm_pin.inst.port = gpioPortA;
-    pwm_pin.inst.pin = 0;
-    pwm_pin.inst.location = 0;
+  for (uint8_t i = 0; i < max_pwm_channels; i++) {
+    pwm_pins[i].pin = PIN_NAME_MAX;
+    pwm_pins[i].inst.timer = get_timer_for_channel(i);
+    pwm_pins[i].inst.channel = get_cc_channel_for_pwm_channel(i);
+    pwm_pins[i].inst.port = gpioPortA;
+    pwm_pins[i].inst.pin = 0;
+    pwm_pins[i].inst.location = 0;
   }
 
   this->pwm_mutex = xSemaphoreCreateMutexStatic(&this->pwm_mutex_buf);
@@ -71,7 +71,7 @@ bool PwmClass::init(PinName pin, int frequency)
   this->pwm_pins[pwm_channel_idx].duty_cycle_percent = 101;
   this->pwm_pins[pwm_channel_idx].inst.port = getSilabsPortFromArduinoPin(pin);
   this->pwm_pins[pwm_channel_idx].inst.pin = getSilabsPinFromArduinoPin(pin);
-  this->pwm_pins[pwm_channel_idx].inst.channel = pwm_channel_idx;
+  this->pwm_pins[pwm_channel_idx].inst.channel = get_cc_channel_for_pwm_channel(pwm_channel_idx);
 
   GPIO_PinModeSet(this->pwm_pins[pwm_channel_idx].inst.port, this->pwm_pins[pwm_channel_idx].inst.pin, gpioModePushPull, 0);
   pwm_config.frequency = frequency;
@@ -240,4 +240,24 @@ void PwmClass::deinit_all_pwm_channels()
   }
 }
 
+TIMER_TypeDef* PwmClass::get_timer_for_channel(uint8_t channel_idx)
+{
+  // Channels 0-2 use TIMER0, channels 3-4 use TIMER1
+  if (channel_idx <= 2) {
+    return TIMER0;
+  } else {
+    return TIMER1;
+  }
+}
+
+uint8_t PwmClass::get_cc_channel_for_pwm_channel(uint8_t channel_idx)
+{
+  // Map PWM channel to timer's CC channel
+  if (channel_idx <= 2) {
+    return channel_idx;  // 0->CC0, 1->CC1, 2->CC2
+  } else {
+    return channel_idx - 3;  // 3->CC0, 4->CC1
+  }
+}
+
 arduino::PwmClass PWM;

cores/gecko/pwm.h

@@ -124,7 +124,7 @@ class PwmClass {
   SemaphoreHandle_t pwm_mutex;
   StaticSemaphore_t pwm_mutex_buf;
 
-  static const uint8_t max_pwm_channels = 3u;
+  static const uint8_t max_pwm_channels = 5u;
   static const uint32_t pwm_stabilization_time_ms = 2u;
 
   uint32_t duty_cycle_set_time;
@@ -165,6 +165,24 @@ class PwmClass {
    *****************************************************************************/
   uint8_t get_num_of_pwm_channels_in_use();
 
+  /**************************************************************************//**
+   * Returns the timer peripheral for the given PWM channel index
+   *
+   * @param[in] channel_idx PWM channel index (0-4)
+   *
+   * @return Pointer to timer peripheral (TIMER0 or TIMER1)
+   *****************************************************************************/
+  TIMER_TypeDef* get_timer_for_channel(uint8_t channel_idx);
+
+  /**************************************************************************//**
+   * Returns the compare/capture channel number for the given PWM channel index
+   *
+   * @param[in] channel_idx PWM channel index (0-4)
+   *
+   * @return CC channel number (0, 1, or 2)
+   *****************************************************************************/
+  uint8_t get_cc_channel_for_pwm_channel(uint8_t channel_idx);
+
   /**************************************************************************//**
    * Deinitializes all active PWM channels
    *****************************************************************************/

libraries/SiliconLabs/examples/pwm_multi_channel/pwm_multi_channel.ino

@@ -0,0 +1,89 @@
+/*
+   Multi-Channel PWM
+
+   This sketch demonstrates the use of up to 5 simultaneous PWM channels on Silicon Labs boards.
+   Each channel can have an independent duty cycle (0-100%), all running at the same frequency (1kHz default).
+
+   The sketch outputs PWM signals with different duty cycles on pins D3-D7:
+   - D3: 20% duty cycle
+   - D4: 40% duty cycle
+   - D5: 60% duty cycle
+   - D6: 80% duty cycle
+   - D7: 100% duty cycle (always HIGH)
+
+   You can connect LEDs (with appropriate current-limiting resistors) to these pins to see
+   different brightness levels, or measure the PWM signals with an oscilloscope.
+
+   Hardware Implementation:
+   - Channels 0-2 use TIMER0 (CC0, CC1, CC2)
+   - Channels 3-4 use TIMER1 (CC0, CC1)
+   - All channels share the same frequency (GSDK constraint)
+   - Each channel has independent duty cycle control
+
+   Compatible with all Silicon Labs Arduino boards.
+
+   Author: Greg Matthew Crossley (github.com/gregmatthewcrossley)
+ */
+
+// Define PWM output pins
+#define PWM_PIN_1  D3
+#define PWM_PIN_2  D4
+#define PWM_PIN_3  D5
+#define PWM_PIN_4  D6
+#define PWM_PIN_5  D7
+
+// Define duty cycles (0-255, where 255 = 100%)
+#define DUTY_20_PERCENT   51   // 20% of 255
+#define DUTY_40_PERCENT   102  // 40% of 255
+#define DUTY_60_PERCENT   153  // 60% of 255
+#define DUTY_80_PERCENT   204  // 80% of 255
+#define DUTY_100_PERCENT  255  // 100% of 255
+
+void setup()
+{
+  Serial.begin(115200);
+  delay(2000);  // Wait for Serial connection
+
+  Serial.println("Multi-Channel PWM Demo");
+  Serial.println();
+  Serial.println("This demo shows 5 simultaneous PWM channels");
+  Serial.println("with different duty cycles on pins D3-D7.");
+  Serial.println();
+
+  // Configure pins as outputs
+  pinMode(PWM_PIN_1, OUTPUT);
+  pinMode(PWM_PIN_2, OUTPUT);
+  pinMode(PWM_PIN_3, OUTPUT);
+  pinMode(PWM_PIN_4, OUTPUT);
+  pinMode(PWM_PIN_5, OUTPUT);
+
+  // Start PWM on all 5 channels with different duty cycles
+  Serial.println("Starting PWM channels...");
+
+  analogWrite(PWM_PIN_1, DUTY_20_PERCENT);
+  Serial.println("  D3: 20% duty cycle");
+
+  analogWrite(PWM_PIN_2, DUTY_40_PERCENT);
+  Serial.println("  D4: 40% duty cycle");
+
+  analogWrite(PWM_PIN_3, DUTY_60_PERCENT);
+  Serial.println("  D5: 60% duty cycle");
+
+  analogWrite(PWM_PIN_4, DUTY_80_PERCENT);
+  Serial.println("  D6: 80% duty cycle");
+
+  analogWrite(PWM_PIN_5, DUTY_100_PERCENT);
+  Serial.println("  D7: 100% duty cycle (always HIGH)");
+
+  Serial.println();
+  Serial.println("All PWM channels active at 1kHz frequency!");
+  Serial.println("Connect LEDs or an oscilloscope to see the outputs.");
+}
+
+void loop()
+{
+  // PWM continues running automatically
+  // You can add code here to dynamically change duty cycles if desired
+
+  delay(1000);
+}

test/build/test_build.py

@@ -163,6 +163,7 @@
     "../../libraries/SiliconLabs/examples/ble_xg27_devkit_sensors/ble_xg27_devkit_sensors.ino":                        xg27devkit_ble_silabs,
     "../../libraries/SiliconLabs/examples/dac_sawtooth/dac_sawtooth.ino":                                              boards_with_dac,
     "../../libraries/SiliconLabs/examples/hwinfo/hwinfo.ino":                                                          all_variants,
+    "../../libraries/SiliconLabs/examples/pwm_multi_channel/pwm_multi_channel.ino":                                    all_variants,
     "../../libraries/SiliconLabs/examples/xg27devkit_sensors/xg27devkit_sensors.ino":                                  xg27devkit_ble_silabs,
     "../../libraries/SiliconLabs/examples/thingplusmatter_debug_unix/thingplusmatter_debug_unix.ino":                  all_ble_silabs,
     "../../libraries/SiliconLabs/examples/thingplusmatter_debug_win/thingplusmatter_debug_win.ino":                    all_ble_silabs,

test/build/test_sketch/test_sketch.ino

@@ -62,7 +62,11 @@ void setup()
   val = analogRead(PA1);
   Serial.println(val, OCT);
 
-  analogWrite(PA0, 128);
+  analogWrite(PA0, 51);
+  analogWrite(PA1, 102);
+  analogWrite(PA2, 153);
+  analogWrite(PA3, 204);
+  analogWrite(PA4, 255);
 
   tone(PA0, 440, 0);
   noTone(PA0);