/// \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);
}
/// \method read()
/// Read the value on the analog pin and return it. The returned value
/// will be between 0 and 4095.
STATIC mp_obj_t adc_read(mp_obj_t self_in) {
pyb_obj_adc_t *self = self_in;
adc_config_channel(&self->handle, self->channel);
uint32_t data = adc_read_channel(&self->handle);
return mp_obj_new_int(data);
}
/// \method read_timed(buf, freq)
/// Read analog values into the given buffer at the given frequency. Buffer
/// can be bytearray or array.array for example. If a buffer with 8-bit elements
/// is used, sample resolution will be reduced to 8 bits.
///
/// Example:
///
/// 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);
int typesize = mp_binary_get_size('@', bufinfo.typecode, NULL);
// Init TIM6 at the required frequency (in Hz)
timer_tim6_init(mp_obj_get_int(freq_in));
// 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
adc_config_channel(self);
for (uint index = 0; index < bufinfo.len; index++) {
// Wait for the timer to trigger
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 (typesize == 1) {
value >>= 4;
}
mp_binary_set_val_array_from_int(bufinfo.typecode, bufinfo.buf, index, value);
}
/// \method read_timed(buf, freq)
/// Read analog values into the given buffer at the given frequency. Buffer
/// can be bytearray or array.array for example. If a buffer with 8-bit elements
/// is used, sample resolution will be reduced to 8 bits.
///
/// Example:
///
/// 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);
int typesize = mp_binary_get_size('@', bufinfo.typecode, NULL);
// Init TIM6 at the required frequency (in Hz)
timer_tim6_init(mp_obj_get_int(freq_in));
// Start timer
HAL_TIM_Base_Start(&TIM6_Handle);
// 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 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);
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);
}
STATIC uint32_t adc_config_and_read_channel(ADC_HandleTypeDef *adcHandle, uint32_t channel) {
adc_config_channel(adcHandle, channel);
uint32_t raw_value = adc_read_channel(adcHandle);
#if defined(STM32F4) || defined(STM32F7)
// ST docs say that (at least on STM32F42x and STM32F43x), VBATE must
// be disabled when TSVREFE is enabled for TEMPSENSOR and VREFINT
// conversions to work. VBATE is enabled by the above call to read
// the channel, and here we disable VBATE so a subsequent call for
// TEMPSENSOR or VREFINT works correctly.
if (channel == ADC_CHANNEL_VBAT) {
ADC->CCR &= ~ADC_CCR_VBATE;
}
#endif
return raw_value;
}
