[request] Increase number of supported PWM channels from 3 to 5

[gregmatthewcrossley]

Summary

As per my post in the /silabs subreddit, it seems as though this core doesn't allow Arduino users to make use of more than 3 PWM pins, despite the MCU supporting more than that.

It was confusing to me because the Arduino Nano Matter product page specifies that up to 5 PWM channels can be used concurrently.

I know this repo isn't accepting community PRs right now, but here's what I've tried so far (without success):

1. On cores/gecko/pwm.h, change line 127 from:

  static const uint8_t max_pwm_channels = 3u;

to:

  static const uint8_t max_pwm_channels = 5u;

2. On cores/gecko/pwm.cpp, add below line 27:

#include "em_cmu.h"

and change line 74 from:

  this->pwm_pins[pwm_channel_idx].inst.channel = pwm_channel_idx;

to:

  // Map pwm_channel_idx to (timer, channel) pairs
  // Each timer has 3 channels (0, 1, 2)
  // Channels 0-2 use TIMER0, channels 3-5 use TIMER1, etc.
  uint8_t timer_num = pwm_channel_idx / 3;
  uint8_t channel_num = pwm_channel_idx % 3;

  TIMER_TypeDef* timer_map[] = {TIMER0, TIMER1, TIMER2, TIMER3, TIMER4};
  this->pwm_pins[pwm_channel_idx].inst.timer = timer_map[timer_num];
  this->pwm_pins[pwm_channel_idx].inst.channel = channel_num;

  // Enable the clock for the timer peripheral
  CMU_Clock_TypeDef timer_clocks[] = {cmuClock_TIMER0, cmuClock_TIMER1, cmuClock_TIMER2, cmuClock_TIMER3, cmuClock_TIMER4};
  CMU_ClockEnable(timer_clocks[timer_num], true);

and change line 78 from:

sl_pwm_init(&this->pwm_pins[pwm_channel_idx].inst, &pwm_config);

to:

  // Initialize the PWM - check if it succeeds
  sl_status_t status = sl_pwm_init(&this->pwm_pins[pwm_channel_idx].inst, &pwm_config);
  if (status != SL_STATUS_OK) {
    // PWM init failed - mark channel as free again
    this->pwm_pins[pwm_channel_idx].pin = PIN_NAME_MAX;
    return false;
  }