stmhal, timer: Factor code to compute PWM percent; improve 32bit case.
Also do the same for teensy timer code.
diff --git a/stmhal/timer.c b/stmhal/timer.c
index 2bd8279..93f66c6 100644
--- a/stmhal/timer.c
+++ b/stmhal/timer.c
@@ -139,7 +139,7 @@
// The following yields TIM_IT_UPDATE when channel is zero and
// TIM_IT_CC1..TIM_IT_CC4 when channel is 1..4
#define TIMER_IRQ_MASK(channel) (1 << (channel))
-#define TIMER_CNT_MASK(self) ((self)->is_32bit ? 0x3fffffff : 0xffff)
+#define TIMER_CNT_MASK(self) ((self)->is_32bit ? 0xffffffff : 0xffff)
#define TIMER_CHANNEL(self) ((((self)->channel) - 1) << 2)
TIM_HandleTypeDef TIM3_Handle;
@@ -268,6 +268,37 @@
STATIC const mp_obj_type_t pyb_timer_channel_type;
+// Helper function to compute PWM value from timer period and percent value.
+// 'val' can be an int or a float between 0 and 100 (out of range values are
+// clamped).
+STATIC uint32_t compute_pwm_value_from_percent(uint32_t period, mp_obj_t val) {
+ uint32_t cmp;
+ if (0) {
+ #if MICROPY_PY_BUILTINS_FLOAT
+ } else if (MP_OBJ_IS_TYPE(val, &mp_type_float)) {
+ cmp = mp_obj_get_float(val) / 100.0 * period;
+ #endif
+ } else {
+ // For integer arithmetic, if period is large and 100*period will
+ // overflow, then divide period before multiplying by cmp. Otherwise
+ // do it the other way round to retain precision.
+ // TODO we really need an mp_obj_get_uint_clamped function here so
+ // that we can get long-int values as large as 0xffffffff.
+ cmp = mp_obj_get_int(val);
+ if (period > (1 << 31) / 100) {
+ cmp = cmp * (period / 100);
+ } else {
+ cmp = (cmp * period) / 100;
+ }
+ }
+ if (cmp < 0) {
+ cmp = 0;
+ } else if (cmp > period) {
+ cmp = period;
+ }
+ return cmp;
+}
+
STATIC void pyb_timer_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
pyb_timer_obj_t *self = self_in;
@@ -568,7 +599,7 @@
STATIC const mp_arg_t pyb_timer_channel_args[] = {
{ MP_QSTR_callback, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
{ MP_QSTR_pin, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
- { MP_QSTR_pulse_width, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+ { MP_QSTR_pulse_width, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_pulse_width_percent, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
{ MP_QSTR_compare, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
@@ -663,30 +694,19 @@
case CHANNEL_MODE_PWM_INVERTED: {
TIM_OC_InitTypeDef oc_config;
oc_config.OCMode = channel_mode_info[chan->mode].oc_mode;
- if (vals[2].u_int != 0xffffffff) {
- // absolute pulse width value given
- oc_config.Pulse = vals[2].u_int;
- } else if (vals[3].u_obj != mp_const_none) {
+ if (vals[3].u_obj != mp_const_none) {
// pulse width percent given
uint32_t period = (__HAL_TIM_GetAutoreload(&self->tim) & TIMER_CNT_MASK(self)) + 1;
- uint32_t cmp;
-#if MICROPY_PY_BUILTINS_FLOAT
- if (MP_OBJ_IS_TYPE(vals[3].u_obj, &mp_type_float)) {
- cmp = mp_obj_get_float(vals[3].u_obj) * period / 100.0;
- } else
-#endif
- {
- cmp = mp_obj_get_int(vals[3].u_obj) * period / 100;
+ // For 32-bit timer, maximum period + 1 will overflow. In that
+ // case we set the period back to 0xffffffff which will give very
+ // close to the correct result for the percentage calculation.
+ if (period == 0) {
+ period = 0xffffffff;
}
- if (cmp < 0) {
- cmp = 0;
- } else if (cmp > period) {
- cmp = period;
- }
- oc_config.Pulse = cmp;
+ oc_config.Pulse = compute_pwm_value_from_percent(period, vals[3].u_obj);
} else {
- // nothing given, default to pulse width of 0
- oc_config.Pulse = 0;
+ // use absolute pulse width value (defaults to 0 if nothing given)
+ oc_config.Pulse = vals[2].u_int;
}
oc_config.OCPolarity = TIM_OCPOLARITY_HIGH;
oc_config.OCNPolarity = TIM_OCNPOLARITY_HIGH;
@@ -910,38 +930,33 @@
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_timer_channel_capture_compare_obj, 1, 2, pyb_timer_channel_capture_compare);
-/// \method pulse_width_ratio([value])
-/// Get or set the pulse width ratio associated with a channel. The value is
-/// a floating-point number between 0.0 and 1.0, and is relative to the period
-/// of the timer associated with this channel. For example, a ratio of 0.5
-/// would be a 50% duty cycle.
+/// \method pulse_width_percent([value])
+/// Get or set the pulse width percentage associated with a channel. The value
+/// is a number between 0 and 100 and sets the percentage of the timer period
+/// for which the pulse is active. The value can be an integer or
+/// floating-point number for more accuracy. For example, a value of 25 gives
+/// a duty cycle of 25%.
STATIC mp_obj_t pyb_timer_channel_pulse_width_percent(mp_uint_t n_args, const mp_obj_t *args) {
pyb_timer_channel_obj_t *self = args[0];
uint32_t period = (__HAL_TIM_GetAutoreload(&self->timer->tim) & TIMER_CNT_MASK(self->timer)) + 1;
+ // For 32-bit timer, maximum period + 1 will overflow. In that case we set
+ // the period back to 0xffffffff which will give very close to the correct
+ // result for the percentage calculation.
+ if (period == 0) {
+ period = 0xffffffff;
+ }
if (n_args == 1) {
// get
uint32_t cmp = __HAL_TIM_GetCompare(&self->timer->tim, TIMER_CHANNEL(self)) & TIMER_CNT_MASK(self->timer);
-#if MICROPY_PY_BUILTINS_FLOAT
- return mp_obj_new_float((float)cmp * 100.0 / (float)period);
-#else
+ #if MICROPY_PY_BUILTINS_FLOAT
+ return mp_obj_new_float((float)cmp / (float)period * 100.0);
+ #else
+ // TODO handle overflow of multiplication for 32-bit timer
return mp_obj_new_int(cmp * 100 / period);
-#endif
+ #endif
} else {
// set
- uint32_t cmp;
-#if MICROPY_PY_BUILTINS_FLOAT
- if (MP_OBJ_IS_TYPE(args[1], &mp_type_float)) {
- cmp = mp_obj_get_float(args[1]) * period / 100.0;
- } else
-#endif
- {
- cmp = mp_obj_get_int(args[1]) * period / 100;
- }
- if (cmp < 0) {
- cmp = 0;
- } else if (cmp > period) {
- cmp = period;
- }
+ uint32_t cmp = compute_pwm_value_from_percent(period, args[1]);
__HAL_TIM_SetCompare(&self->timer->tim, TIMER_CHANNEL(self), cmp & TIMER_CNT_MASK(self->timer));
return mp_const_none;
}