Commit dfad7f47 authored by Damien George's avatar Damien George
Browse files

stmhal: Optimise ADC.read_timed() so that it can sample up to 750kHz.

parent 44cd46a7
......@@ -225,22 +225,49 @@ STATIC mp_obj_t adc_read_timed(mp_obj_t self_in, mp_obj_t buf_in, mp_obj_t freq_
// Start timer
HAL_TIM_Base_Start(&TIM6_Handle);
// This uses the timer in polling mode to do the sampling
// We could use DMA, but then we can't convert the values correctly for the buffer
// configure the ADC channel
adc_config_channel(self);
// This uses the timer in polling mode to do the sampling
// TODO use DMA
uint nelems = bufinfo.len / typesize;
for (uint index = 0; index < nelems; index++) {
// Wait for the timer to trigger
// Wait for the timer to trigger so we sample at the correct frequency
while (__HAL_TIM_GET_FLAG(&TIM6_Handle, TIM_FLAG_UPDATE) == RESET) {
}
__HAL_TIM_CLEAR_FLAG(&TIM6_Handle, TIM_FLAG_UPDATE);
uint value = adc_read_channel(&self->handle);
if (index == 0) {
// for the first sample we need to turn the ADC on
HAL_ADC_Start(&self->handle);
} else {
// for subsequent samples we can just set the "start sample" bit
ADCx->CR2 |= (uint32_t)ADC_CR2_SWSTART;
}
// wait for sample to complete
uint32_t tickstart = HAL_GetTick();
while ((ADCx->SR & ADC_FLAG_EOC) != ADC_FLAG_EOC) {
#define READ_TIMED_TIMEOUT (10) // in ms
if (((HAL_GetTick() - tickstart ) > READ_TIMED_TIMEOUT)) {
break; // timeout
}
}
// read value
uint value = ADCx->DR;
// store value in buffer
if (typesize == 1) {
value >>= 4;
}
mp_binary_set_val_array_from_int(bufinfo.typecode, bufinfo.buf, index, value);
}
// turn the ADC off
HAL_ADC_Stop(&self->handle);
// Stop timer
HAL_TIM_Base_Stop(&TIM6_Handle);
......
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