HI, When I use the SAADC example, I found that the data collected during the simultaneous 8-channel acquisition has abnormal data on both channels。
I've ported the SAADC program to it ：nRF5_SDK_12.3.0_d7731ad\examples\ble_peripheral\ble_app_uart\pca10040\s132\arm5_no_packs
#define SAMPLES_IN_BUFFER 8
volatile uint8_t state = 1;
static const nrf_drv_timer_t m_timer = NRF_DRV_TIMER_INSTANCE(3);
static nrf_saadc_value_t m_buffer_pool[2][SAMPLES_IN_BUFFER];
static nrf_ppi_channel_t m_ppi_channel;
static uint32_t m_adc_evt_counter;
void timer_handler(nrf_timer_event_t event_type, void * p_context)
{
}
void saadc_sampling_event_init(void)
{
ret_code_t err_code;
err_code = nrf_drv_ppi_init();
APP_ERROR_CHECK(err_code);
nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
timer_cfg.bit_width = NRF_TIMER_BIT_WIDTH_32;
err_code = nrf_drv_timer_init(&m_timer, &timer_cfg, timer_handler);
APP_ERROR_CHECK(err_code);
/* setup m_timer for compare event every 400ms */
uint32_t ticks = nrf_drv_timer_ms_to_ticks(&m_timer, 400);
nrf_drv_timer_extended_compare(&m_timer,
NRF_TIMER_CC_CHANNEL0,
ticks,
NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
false);
nrf_drv_timer_enable(&m_timer);
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);
int i;
//NRF_LOG_INFO("ADC event number: %d\r\n", (int)m_adc_evt_counter);
printf("ADC event number: %d\r\n", (int)m_adc_evt_counter);
for (i = 0; i < SAMPLES_IN_BUFFER; i++)
{
//NRF_LOG_INFO("%d\r\n", p_event->data.done.p_buffer[i]);
printf("%d\r\n", p_event->data.done.p_buffer[i]);
}
m_adc_evt_counter++;
}
}
void saadc_init(void)
{
ret_code_t err_code;
nrf_drv_saadc_config_t saadc_config = NRF_DRV_SAADC_DEFAULT_CONFIG;
saadc_config.resolution = NRF_SAADC_RESOLUTION_12BIT;
err_code = nrf_drv_saadc_init(NULL, saadc_callback);
APP_ERROR_CHECK(err_code);
nrf_saadc_channel_config_t channel_config =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);
nrf_saadc_channel_config_t channel_config1 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);
nrf_saadc_channel_config_t channel_config2 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN2);
nrf_saadc_channel_config_t channel_config3 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN3);
nrf_saadc_channel_config_t channel_config4 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN4);
nrf_saadc_channel_config_t channel_config5 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN5);
nrf_saadc_channel_config_t channel_config6 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN6);
nrf_saadc_channel_config_t channel_config7 =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN7);
err_code = nrf_drv_saadc_channel_init(0, &channel_config);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(1, &channel_config1);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(2, &channel_config2);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(3, &channel_config3);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(4, &channel_config4);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(5, &channel_config5);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(6, &channel_config6);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(7, &channel_config7);
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)
{
uint32_t err_code;
bool erase_bonds;
//Initialize.
APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
uart_init();
buttons_leds_init(&erase_bonds);
ble_stack_init();
gap_params_init();
services_init();
advertising_init();
conn_params_init();
printf("\r\nUART Start!\r\n");
err_code = ble_advertising_start(BLE_ADV_MODE_FAST);
APP_ERROR_CHECK(err_code);
printf("SAADC HAL simple example.\r\n");
saadc_init();
saadc_sampling_event_init();
saadc_sampling_event_enable();
//Enter main loop.
for (;;)
{
power_manage();
}
}
This is the conversion result
ADC event number: 9
40
31
26
336
129
83
66
60
The voltage of these eight channels are the same about 0.6v
