stmhal: Reset the timer counter to zero after changing the auto reload.

dhylands · dpgeorge · commit fd787c5e4ed3 · 2015-04-22T23:31:56.000+01:00
Because if the counter is above the new value of the auto-reload register
then it may be a long time until the timer wraps around.
diff --git a/stmhal/timer.c b/stmhal/timer.c
@@ -1088,6 +1088,10 @@ STATIC mp_obj_t pyb_timer_freq(mp_uint_t n_args, const mp_obj_t *args) {
         uint32_t prescaler = compute_prescaler_period_from_freq(self, args[1], &period);
         self->tim.Instance->PSC = prescaler;
         __HAL_TIM_SetAutoreload(&self->tim, period);
+        // Reset the counter to zero. Otherwise, if counter >= period it will
+        // continue counting until it wraps (at either 16 or 32 bits depending
+        // on the timer).
+        __HAL_TIM_SetCounter(&self->tim, 0);
         return mp_const_none;
     }
 }
@@ -1118,6 +1122,10 @@ STATIC mp_obj_t pyb_timer_period(mp_uint_t n_args, const mp_obj_t *args) {
     } else {
         // set
         __HAL_TIM_SetAutoreload(&self->tim, mp_obj_get_int(args[1]) & TIMER_CNT_MASK(self));
+        // Reset the counter to zero. Otherwise, if counter >= period it will
+        // continue counting until it wraps (at either 16 or 32 bits depending
+        // on the timer).
+        __HAL_TIM_SetCounter(&self->tim, 0); 
         return mp_const_none;
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -1088,6 +1088,10 @@ STATIC mp_obj_t pyb_timer_freq(mp_uint_t n_args, const mp_obj_t *args) {`
`1088`	`1088`	`uint32_t prescaler = compute_prescaler_period_from_freq(self, args[1], &period);`
`1089`	`1089`	`self->tim.Instance->PSC = prescaler;`
`1090`	`1090`	`__HAL_TIM_SetAutoreload(&self->tim, period);`
	`1091`	`+ // Reset the counter to zero. Otherwise, if counter >= period it will`
	`1092`	`+ // continue counting until it wraps (at either 16 or 32 bits depending`
	`1093`	`+ // on the timer).`
	`1094`	`+ __HAL_TIM_SetCounter(&self->tim, 0);`
`1091`	`1095`	`return mp_const_none;`
`1092`	`1096`	`}`
`1093`	`1097`	`}`
`@@ -1118,6 +1122,10 @@ STATIC mp_obj_t pyb_timer_period(mp_uint_t n_args, const mp_obj_t *args) {`
`1118`	`1122`	`} else {`
`1119`	`1123`	`// set`
`1120`	`1124`	`__HAL_TIM_SetAutoreload(&self->tim, mp_obj_get_int(args[1]) & TIMER_CNT_MASK(self));`
	`1125`	`+ // Reset the counter to zero. Otherwise, if counter >= period it will`
	`1126`	`+ // continue counting until it wraps (at either 16 or 32 bits depending`
	`1127`	`+ // on the timer).`
	`1128`	`+ __HAL_TIM_SetCounter(&self->tim, 0);`
`1121`	`1129`	`return mp_const_none;`
`1122`	`1130`	`}`
`1123`	`1131`	`}`