Hi,
Here is my code.
I plan to use 3 ADC (2 single ended, 1 differential) on NRF52832.
#define SAMPLES_IN_BUFFER (3)
#define TEMP_pin (NRF_SAADC_INPUT_AIN7)
#define BAT_ADC_pin (NRF_SAADC_INPUT_AIN6)
#define DIFF_P_pin (NRF_SAADC_INPUT_AIN5)
#define DIFF_N_pin (NRF_SAADC_INPUT_AIN4)
const nrf_drv_timer_t MY_TIMER_0 = NRF_DRV_TIMER_INSTANCE(0);
static const nrf_drv_timer_t m_timer = NRF_DRV_TIMER_INSTANCE(0);
static nrf_saadc_value_t m_buffer_pool[2][SAMPLES_IN_BUFFER];
static nrf_ppi_channel_t m_ppi_channel;
#define NRF_DRV_SAADC_SINGLE_ENDED(PIN_P, GAIN) \
{ \
.resistor_p = NRF_SAADC_RESISTOR_DISABLED, \
.resistor_n = NRF_SAADC_RESISTOR_DISABLED, \
.gain = GAIN, \
.reference = NRF_SAADC_REFERENCE_INTERNAL, \
.acq_time = NRF_SAADC_ACQTIME_10US, \
.mode = NRF_SAADC_MODE_SINGLE_ENDED, \
.burst = NRF_SAADC_BURST_DISABLED, \
.pin_p = (nrf_saadc_input_t)(PIN_P), \
.pin_n = NRF_SAADC_INPUT_DISABLED \
}
#define NRF_DRV_SAADC_DIFFERENTIAL(PIN_P, PIN_N, GAIN) \
{ \
.resistor_p = NRF_SAADC_RESISTOR_DISABLED, \
.resistor_n = NRF_SAADC_RESISTOR_DISABLED, \
.gain = GAIN, \
.reference = NRF_SAADC_REFERENCE_INTERNAL, \
.acq_time = NRF_SAADC_ACQTIME_10US, \
.mode = NRF_SAADC_MODE_DIFFERENTIAL, \
.pin_p = (nrf_saadc_input_t)(PIN_P), \
.pin_n = (nrf_saadc_input_t)(PIN_N) \
}
//=========================================================================
//=========================================================================
void saadc_sampling_event_init(void) {
ret_code_t err_code;
err_code = nrf_drv_ppi_init();
APP_ERROR_CHECK(err_code);
uint32_t timer_compare_event_addr = nrf_drv_timer_compare_event_address_get(&m_timer,
NRF_TIMER_CC_CHANNEL0);
uint32_t saadc_sample_task_addr = nrf_drv_saadc_sample_task_get();
/* setup ppi channel so that timer compare event is triggering sample task in SAADC */
err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_ppi_channel_assign(m_ppi_channel,
timer_compare_event_addr,
saadc_sample_task_addr);
APP_ERROR_CHECK(err_code);
}
//=========================================================================
//=========================================================================
void saadc_sampling_event_enable(void) {
ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);
APP_ERROR_CHECK(err_code);
}
//=========================================================================
//=========================================================================
void saadc_callback(nrf_drv_saadc_evt_t const * p_event) {
if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
{
ret_code_t err_code;
err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);
printf("%5d, %5d, %5d\n", p_event->data.done.p_buffer[0], p_event->data.done.p_buffer[1], p_event->data.done.p_buffer[2]);
}
}
//=========================================================================
//=========================================================================
void saadc_init(void) {
ret_code_t err_code;
err_code = nrf_drv_saadc_init(NULL, saadc_callback);
APP_ERROR_CHECK(err_code);
nrf_saadc_resolution_set(NRF_SAADC_RESOLUTION_12BIT);
// channel 0
// ADC range = 0.6V / GAIN = 0.6 / (1/6) = 3.6V
nrf_saadc_channel_config_t channel_0_config = NRF_DRV_SAADC_SINGLE_ENDED(BAT_ADC_pin, NRF_SAADC_GAIN1_6);
err_code = nrf_drv_saadc_channel_init(0, &channel_0_config);
APP_ERROR_CHECK(err_code);
// channel 1
// ADC range = 0.6V / GAIN = 0.6 / (1/2) = 1.2V
nrf_saadc_channel_config_t channel_1_config = NRF_DRV_SAADC_SINGLE_ENDED(TEMP_pin, NRF_SAADC_GAIN1_6);
err_code = nrf_drv_saadc_channel_init(1, &channel_1_config);
APP_ERROR_CHECK(err_code);
// channel 2
// ADC range = 0.6V / GAIN = 0.6 / 1 = +-0.6 V
// ADC range = 0.6V / GAIN = 0.6 / 2 = +-0.3 V
// ADC range = 0.6V / GAIN = 0.6 / 4 = +-0.15V
nrf_saadc_channel_config_t channel_2_config = NRF_DRV_SAADC_DIFFERENTIAL(DIFF_P_pin, DIFF_N_pin, NRF_SAADC_GAIN1);
err_code = nrf_drv_saadc_channel_init(2, &channel_2_config);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);
}
//=========================================================================
//=========================================================================
int main(void) {
nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
nrf_drv_timer_init(&MY_TIMER_0, &timer_cfg, &my_timer_handler);
nrf_drv_timer_extended_compare(&MY_TIMER_0,
NRF_TIMER_CC_CHANNEL0,
nrf_drv_timer_ms_to_ticks(&MY_TIMER_0, 50),
NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
true);
nrf_drv_timer_enable(&MY_TIMER_0);
//
saadc_init();
saadc_sampling_event_init();
saadc_sampling_event_enable();
}
Only the first time convert, I can get correct order output ADC_ch0, ADC_ch1 and ADC_ch2,
otherwise, I discover the output order is ADC_ch2, ADC_ch0 and ADC_ch1.
How to solve this problem?
