/// \method read_timed(buf, timer) /// /// Read analog values into `buf` at a rate set by the `timer` object. /// /// `buf` can be bytearray or array.array for example. The ADC values have /// 12-bit resolution and are stored directly into `buf` if its element size is /// 16 bits or greater. If `buf` has only 8-bit elements (eg a bytearray) then /// the sample resolution will be reduced to 8 bits. /// /// `timer` should be a Timer object, and a sample is read each time the timer /// triggers. The timer must already be initialised and running at the desired /// sampling frequency. /// /// To support previous behaviour of this function, `timer` can also be an /// integer which specifies the frequency (in Hz) to sample at. In this case /// Timer(6) will be automatically configured to run at the given frequency. /// /// Example using a Timer object (preferred way): /// /// adc = pyb.ADC(pyb.Pin.board.X19) # create an ADC on pin X19 /// tim = pyb.Timer(6, freq=10) # create a timer running at 10Hz /// buf = bytearray(100) # creat a buffer to store the samples /// adc.read_timed(buf, tim) # sample 100 values, taking 10s /// /// Example using an integer for the frequency: /// /// adc = pyb.ADC(pyb.Pin.board.X19) # create an ADC on pin X19 /// buf = bytearray(100) # create a buffer of 100 bytes /// adc.read_timed(buf, 10) # read analog values into buf at 10Hz /// # this will take 10 seconds to finish /// for val in buf: # loop over all values /// print(val) # print the value out /// /// This function does not allocate any memory. STATIC mp_obj_t adc_read_timed(mp_obj_t self_in, mp_obj_t buf_in, mp_obj_t freq_in) { pyb_obj_adc_t *self = self_in; mp_buffer_info_t bufinfo; mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_WRITE); size_t typesize = mp_binary_get_size('@', bufinfo.typecode, NULL); TIM_HandleTypeDef *tim; #if defined(TIM6) if (mp_obj_is_integer(freq_in)) { // freq in Hz given so init TIM6 (legacy behaviour) tim = timer_tim6_init(mp_obj_get_int(freq_in)); HAL_TIM_Base_Start(tim); } else #endif { // use the supplied timer object as the sampling time base tim = pyb_timer_get_handle(freq_in); } // configure the ADC channel adc_config_channel(&self->handle, self->channel); // 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 so we sample at the correct frequency while (__HAL_TIM_GET_FLAG(tim, TIM_FLAG_UPDATE) == RESET) { } __HAL_TIM_CLEAR_FLAG(tim, TIM_FLAG_UPDATE); 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 #if defined(STM32F4) || defined(STM32F7) ADCx->CR2 |= (uint32_t)ADC_CR2_SWSTART; #elif defined(STM32L4) SET_BIT(ADCx->CR, ADC_CR_ADSTART); #else #error Unsupported processor #endif } // wait for sample to complete #define READ_TIMED_TIMEOUT (10) // in ms adc_wait_for_eoc_or_timeout(READ_TIMED_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); }
STATIC uint32_t adc_read_channel(ADC_HandleTypeDef *adcHandle) { HAL_ADC_Start(adcHandle); adc_wait_for_eoc_or_timeout(EOC_TIMEOUT); uint32_t value = ADCx->DR; HAL_ADC_Stop(adcHandle); return value; }