stm32/timer: Cannot specify timer callbacks using callback().

[yn386]

This PR fixes issue #8732.

MicroPython Version

v1.19.1

How to reproduce

Execute attached in #8732.
Specified callback is not called.

Detail of changes

Since HAL version 1.17.0, HAL_TIM_IC_Start_IT() checks whether specified channel of timer is busy or not.

+HAL_StatusTypeDef HAL_TIM_IC_Start_IT(TIM_HandleTypeDef *htim, uint32_t Channel)
 {
+  uint32_t tmpsmcr;
+  HAL_TIM_ChannelStateTypeDef channel_state = TIM_CHANNEL_STATE_GET(htim, Channel);
+  HAL_TIM_ChannelStateTypeDef complementary_channel_state = TIM_CHANNEL_N_STATE_GET(htim, Channel);
+
   /* Check the parameters */
   assert_param(IS_TIM_CCX_INSTANCE(htim->Instance, Channel));

+  /* Check the TIM channel state */
+  if ((channel_state != HAL_TIM_CHANNEL_STATE_READY)
+      || (complementary_channel_state != HAL_TIM_CHANNEL_STATE_READY))
+  {
+    return HAL_ERROR;
+  }
+
+  /* Set the TIM channel state */
+  TIM_CHANNEL_STATE_SET(htim, Channel, HAL_TIM_CHANNEL_STATE_BUSY);
+  TIM_CHANNEL_N_STATE_SET(htim, Channel, HAL_TIM_CHANNEL_STATE_BUSY);
+

For more detail of changes, see git diff 540ae5c5 9153dc73 STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_tim.c in lib/stm32lib.

timer.c calls HAL_TIM_IC_Start() when callback parameter is not specified.

micropython/ports/stm32/timer.c

Lines 1249 to 1253 in 0b26efe

	if (chan->callback == mp_const_none) {
	HAL_TIM_IC_Start(&self->tim, TIMER_CHANNEL(chan));
	} else {
	pyb_timer_channel_callback(MP_OBJ_FROM_PTR(chan), chan->callback);
	}

After callback() is called by python, call HAL_TIM_IC_Start_IT() at

micropython/ports/stm32/timer.c

Lines 1589 to 1591 in 0b26efe

	case CHANNEL_MODE_IC:
	HAL_TIM_IC_Start_IT(&self->timer->tim, TIMER_CHANNEL(self));
	break;

but the timer is already running, so HAL_TIM_IC_Start_IT() returns HAL_ERROR and irq of timer is not enabled here.

This issue is not occurred if Timer.channel() is called with paramerter 'callback' because HAL_TIM_IC_Start_IT() is called in pyb_timer_channel_callback() and irq of timer is enabled.

To prevent this error, call HAL_TIM_IC_Stop_IT() before HAL_TIM_IC_Start_IT().
Mode PWM and OC have same issue, so I also fixed those.

[dpgeorge]

Thank you. Tested on STM32L476DISC and PYBV10 (to check it didn't change behaviour of other MCUs), rebased and merged in 989b8c7

[chrismas9]

@yn386 Thanks for the fix. Tested on NUCLEO_L452RE.