HELP with Burst Mode HRTIM

[GiovanniL]

Hi everyone,

I am working on an STM32G4 project using the HRTIM1 peripheral.

My goal is to generate a burst of exactly 3 PWM pulses on Timer A and Timer B simultaneously, triggered by an External Event (Sync Input / EEV).

The Goal:

1. System waits for an external trigger (e.g., from TIM3 via TRGO or physical pin).

2. Upon trigger, HRTIM Timer A and Timer B start.

3. They output exactly 3 PWM cycles.

4. They stop and wait for the next trigger (Single-Shot Retriggerable).

The Configuration:

I am using STM32CubeIDE and HAL, but I also tried direct register access.

• Master Timer: Acts as a dummy/pass-through for synchronization.

• Timer A & B:

  • Mode: Single-Shot Retriggerable.

  • Prescaler: Div1.

  • Period: 1000 ticks.

  • Repetition Counter: 2 (Targeting $N+1 = 3$ pulses).

  • Start on Sync: Enabled.

  • Reset on Sync: Enabled.

  • Preload Enable: Disabled (To force immediate register update).

The Problem:

Despite setting REPxR = 2, I consistently see only 1 pulse on the scope when the trigger arrives. It seems the timer resets and starts, but the Repetition Counter value is ignored or treated as 0 for the first run.

Any help will be appreciated

Thank you