I am attempting to modify the peripheral_uart example for nRF52833 to send analog data from CH[3] of the saadc to the nrf connect app.
I have enabled the saadc in my sdk_config.h found here \nRF5_SDK_17.1.0_ddde560\config\nrf52833\config\:
#ifndef NRFX_SAADC_ENABLED #define NRFX_SAADC_ENABLED 1 #endif //... #ifndef SAADC_ENABLED #define SAADC_ENABLED 1 #endif
And I have added the following code to my main loop in the example program:
void main(void)
{
// For reading analog pin 2 / channel 3
volatile int16_t result = 0;
volatile float precise_result = 0;
// Start HFCLK from crystal oscillator, this will give the SAADC higher accuracy
NRF_CLOCK->TASKS_HFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
;
NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
// Configure SAADC singled-ended channel, Internal reference (0.6V) and 1/6 gain.
// Read analog from IN_MCU -- AIN2/P0.04 - 10 -- AIN2 is channel 3, page 373: https://infocenter.nordicsemi.com/pdf/nRF52833_OPS_v0.7.pdf
NRF_SAADC->CH[3].CONFIG = (SAADC_CH_CONFIG_GAIN_Gain1_6 << SAADC_CH_CONFIG_GAIN_Pos) |
(SAADC_CH_CONFIG_MODE_SE << SAADC_CH_CONFIG_MODE_Pos) |
(SAADC_CH_CONFIG_REFSEL_Internal << SAADC_CH_CONFIG_REFSEL_Pos) |
(SAADC_CH_CONFIG_RESN_Bypass << SAADC_CH_CONFIG_RESN_Pos) |
(SAADC_CH_CONFIG_RESP_Bypass << SAADC_CH_CONFIG_RESP_Pos) |
(SAADC_CH_CONFIG_TACQ_3us << SAADC_CH_CONFIG_TACQ_Pos);
// Configure the SAADC channel with VDD as positive input, no negative input(single ended).
NRF_SAADC->CH[3].PSELP = SAADC_CH_PSELP_PSELP_VDD << SAADC_CH_PSELP_PSELP_Pos;
NRF_SAADC->CH[3].PSELN = SAADC_CH_PSELN_PSELN_NC << SAADC_CH_PSELN_PSELN_Pos;
// Configure the SAADC resolution.
NRF_SAADC->RESOLUTION = SAADC_RESOLUTION_VAL_14bit << SAADC_RESOLUTION_VAL_Pos;
// Configure result to be put in RAM at the location of "result" variable.
NRF_SAADC->RESULT.MAXCNT = 1;
NRF_SAADC->RESULT.PTR = (uint32_t)&result;
// No automatic sampling, will trigger with TASKS_SAMPLE.
NRF_SAADC->SAMPLERATE = SAADC_SAMPLERATE_MODE_Task << SAADC_SAMPLERATE_MODE_Pos;
// Enable SAADC (would capture analog pins if they were used in CH[0].PSELP)
NRF_SAADC->ENABLE = SAADC_ENABLE_ENABLE_Enabled << SAADC_ENABLE_ENABLE_Pos;
// Calibrate the SAADC (only needs to be done once in a while)
NRF_SAADC->TASKS_CALIBRATEOFFSET = 1;
while (NRF_SAADC->EVENTS_CALIBRATEDONE == 0)
;
NRF_SAADC->EVENTS_CALIBRATEDONE = 0;
while (NRF_SAADC->STATUS == (SAADC_STATUS_STATUS_Busy << SAADC_STATUS_STATUS_Pos))
;
// Start the SAADC and wait for the started event.
NRF_SAADC->TASKS_START = 1;
while (NRF_SAADC->EVENTS_STARTED == 0)
;
NRF_SAADC->EVENTS_STARTED = 0;
// Do a SAADC sample, will put the result in the configured RAM buffer.
NRF_SAADC->TASKS_SAMPLE = 1;
while (NRF_SAADC->EVENTS_END == 0)
;
NRF_SAADC->EVENTS_END = 0;
// Convert the result to voltage
// Result = [V(p) - V(n)] * GAIN/REFERENCE * 2^(RESOLUTION)
// Result = (VDD - 0) * ((1/6) / 0.6) * 2^14
// VDD = Result / 4551.1
precise_result = (float)result / 4551.1f;
precise_result; // to get rid of set but not used warning
// Stop the SAADC, since it's not used anymore.
NRF_SAADC->TASKS_STOP = 1;
while (NRF_SAADC->EVENTS_STOPPED == 0)
;
NRF_SAADC->EVENTS_STOPPED = 0;
uint8_t therm_data[20];
sprintf((char *)therm_data, "%f", precise_result);
// Send measurement to nRF Toolbox app
int err = 0;
err = bt_nus_send(NULL, therm_data, sizeof(therm_data));
if (err)
{
LOG_ERR("Failed to send thermistor data (err: %d)", err);
return;
}
};
I can still see uart data tx and rx, but I do not see any of the analog data I am trying to read and send using bt_nus_send() - am I missing a characteristic or something else? From the documentation it appears that using this function I should be able to send any data: developer.nordicsemi.com/.../nus.html
I aim to just send analog data to one of the nrf apps and would appreciate any resources or pointers in the right direction.
Edit: forgot to add a link
