/// \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 TIMx_Config(mp_obj_t timer) {
// TRGO selection to trigger DAC
TIM_HandleTypeDef *tim = pyb_timer_get_handle(timer);
TIM_MasterConfigTypeDef config;
config.MasterOutputTrigger = TIM_TRGO_UPDATE;
config.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
HAL_TIMEx_MasterConfigSynchronization(tim, &config);
// work out the trigger channel (only certain ones are supported)
if (tim->Instance == TIM2) {
return DAC_TRIGGER_T2_TRGO;
} else if (tim->Instance == TIM4) {
return DAC_TRIGGER_T4_TRGO;
} else if (tim->Instance == TIM5) {
return DAC_TRIGGER_T5_TRGO;
#if defined(TIM6)
} else if (tim->Instance == TIM6) {
return DAC_TRIGGER_T6_TRGO;
#endif
#if defined(TIM7)
} else if (tim->Instance == TIM7) {
return DAC_TRIGGER_T7_TRGO;
#endif
#if defined(TIM8)
} else if (tim->Instance == TIM8) {
return DAC_TRIGGER_T8_TRGO;
#endif
} else {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "Timer does not support DAC triggering"));
}
}
