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[STM32F4] Handle higher range pwm periods 

As first reported on STM32F3 family in #1682, we need to cope
with periods in the seconds range as well. This is fixed here in
the same way as was done for STM32F3 by using the pre-scaler.
pull/2103/head
Laurent MEUNIER 2016-06-28 18:19:58 +02:00
parent ce5ee179cd
commit ab45ef0378
2 changed files with 31 additions and 9 deletions
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1
hal/targets/hal/TARGET_STM/TARGET_STM32F4/common_objects.h
View File

@ -42,6 +42,7 @@ extern "C" {
struct pwmout_s {
PWMName pwm;
PinName pin;
uint32_t prescaler;
uint32_t period;
uint32_t pulse;
uint8_t channel;

35
hal/targets/hal/TARGET_STM/TARGET_STM32F4/pwmout_api.c
View File

@ -94,6 +94,7 @@ void pwmout_init(pwmout_t* obj, PinName pin)
obj->pin = pin;
obj->period = 0;
obj->pulse = 0;
obj->prescaler = 1;
pwmout_period_us(obj, 20000); // 20 ms per default
}
@ -121,7 +122,7 @@ void pwmout_write(pwmout_t* obj, float value)
// Configure channels
sConfig.OCMode = TIM_OCMODE_PWM1;
sConfig.Pulse = obj->pulse;
sConfig.Pulse = obj->pulse / obj->prescaler;
sConfig.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfig.OCNPolarity = TIM_OCNPOLARITY_HIGH;
sConfig.OCFastMode = TIM_OCFAST_DISABLE;
@ -241,12 +242,31 @@ void pwmout_period_us(pwmout_t* obj, int us)
return;
}
TimHandle.Init.Period = us - 1;
/* To make it simple, we use to possible prescaler values which lead to:
* pwm unit = 1us, period/pulse can be from 1us to 65535us
* or
* pwm unit = 500us, period/pulse can be from 500us to ~32.76sec
* Be careful that all the channels of a PWM shares the same prescaler
*/
if (us > 0xFFFF) {
obj->prescaler = 500;
} else {
obj->prescaler = 1;
}
// TIMxCLK = PCLKx when the APB prescaler = 1 else TIMxCLK = 2 * PCLKx
if (APBxCLKDivider == RCC_HCLK_DIV1)
TimHandle.Init.Prescaler = (uint16_t)((PclkFreq) / 1000000) - 1; // 1 us tick
TimHandle.Init.Prescaler = (uint16_t)(((PclkFreq) / 1000000) * obj->prescaler) - 1; // 1 us tick
else
TimHandle.Init.Prescaler = (uint16_t)((PclkFreq * 2) / 1000000) - 1; // 1 us tick
TimHandle.Init.Prescaler = (uint16_t)(((PclkFreq * 2) / 1000000) * obj->prescaler) - 1; // 1 us tick
if (TimHandle.Init.Prescaler > 0xFFFF)
error("PWM: out of range prescaler");
TimHandle.Init.Period = (us - 1) / obj->prescaler;
if (TimHandle.Init.Period > 0xFFFF)
error("PWM: out of range period");
TimHandle.Init.ClockDivision = 0;
TimHandle.Init.CounterMode = TIM_COUNTERMODE_UP;
@ -254,12 +274,12 @@ void pwmout_period_us(pwmout_t* obj, int us)
error("Cannot initialize PWM\n");
}
// Set duty cycle again
pwmout_write(obj, dc);
// Save for future use
obj->period = us;
// Set duty cycle again
pwmout_write(obj, dc);
__HAL_TIM_ENABLE(&TimHandle);
}
@ -276,6 +296,7 @@ void pwmout_pulsewidth_ms(pwmout_t* obj, int ms)
void pwmout_pulsewidth_us(pwmout_t* obj, int us)
{
float value = (float)us / (float)obj->period;
printf("pwmout_pulsewidth_us: period=%d, us=%d, dc=%d%%\r\n", obj->period, us, (int) (value*100));
pwmout_write(obj, value);
}