Xiao SAMD21 cannot sleep and wake from external interrupt

Products & Technology XIAO
6

Hi there,

So I don’t believe so but , I know there is such a thing with other ESP32’s you set it and let the Hardware handle it. The ESP32 uses a subsystem called LEDC (LED Control) for PWM output. It’s hardware-driven and very flexible.

You configure:

  • PWM frequency (e.g., 25 kHz for motor)
  • PWM resolution (e.g., 10 bits for 0–1023)
  • Duty cycle (e.g., 500 for ~50%)
    Then the LEDC peripheral maintains the output without needing CPU cycles.

Sleep Modes and PWM

Sleep Mode LEDC PWM Output? Notes
Light Sleep :white_check_mark: Yes Timer and LEDC stay active, CPU paused
Deep Sleep :x: No Only RTC and ULP stay active — LEDC halts

Something like this is implemented.

ledcSetup(0, 25000, 10);     // Channel 0, 25kHz, 10-bit resolution
ledcAttachPin(5, 0);         // Pin 5 to channel 0
ledcWrite(0, 512);           // 50% duty

// Optionally go to light sleep
esp_sleep_enable_timer_wakeup(1000000); // wake after 1s
esp_light_sleep_start();

HTH
GL :slight_smile: PJ :v:

Samd21 is the light weight Xiao, check the Others too :+1: