ADC_IRQn trouble

[Kevin Choi]

I am having trouble with setting priority of ADC_IRQn.

void ADC_init(void)
{
nrf_adc_config_t nrf_adc_config;
nrf_adc_config.reference = NRF_ADC_CONFIG_REF_VBG;
nrf_adc_config.resolution = NRF_ADC_CONFIG_RES_8BIT;
nrf_adc_config.scaling = NRF_ADC_CONFIG_SCALING_INPUT_ONE_THIRD;
nrf_adc_configure(&nrf_adc_config);
nrf_adc_input_select(NRF_ADC_CONFIG_INPUT_DISABLED);
nrf_adc_int_enable(ADC_INTENSET_END_Enabled << ADC_INTENSET_END_Pos);
sd_nvic_SetPriority(ADC_IRQn, 2);
sd_nvic_EnableIRQ(ADC_IRQn);
}

void ADC_init(void)
{
nrf_adc_config_t nrf_adc_config;
nrf_adc_config.reference = NRF_ADC_CONFIG_REF_VBG;
nrf_adc_config.resolution = NRF_ADC_CONFIG_RES_8BIT;
nrf_adc_config.scaling = NRF_ADC_CONFIG_SCALING_INPUT_ONE_THIRD;
nrf_adc_configure(&nrf_adc_config);
nrf_adc_input_select(NRF_ADC_CONFIG_INPUT_DISABLED);
nrf_adc_int_enable(ADC_INTENSET_END_Enabled << ADC_INTENSET_END_Pos);
sd_nvic_SetPriority(ADC_IRQn, 2);
sd_nvic_EnableIRQ(ADC_IRQn);
}

static uint8_t adc_result = 0;

static void ADC_IRQHandler(void)
{
nrf_adc_conversion_event_clean();
adc_result = nrf_adc_result_get();
//isBattLow = (adc_result < 200);
isBattLow = true;
}

Both nrf_adc_start() and NRF_ADC->TASKS_START = 1 don't trigger ADC_IRQHandler() with above setting.

sd_nvic_SetPriority(ADC_IRQn, NRF_APP_PRIORITY_LOW);
sd_nvic_SetPriority(ADC_IRQn, 3);
sd_nvic_SetPriority(ADC_IRQn, NRF_APP_PRIORITY_HIGH);
sd_nvic_SetPriority(ADC_IRQn, 1);

Both nrf_adc_start() and NRF_ADC->TASKS_START = 1 make the system unresponsive with above 4 settings. I don't understand why it is happening.

[Stefan Birnir Sverrisson]

Hi

When using softdevice, try to use the ADC setup made in this example instead. The ADC init and ADC interrupt handler are at the bottom of the main.c file

[Kevin Choi]

I appreciate your response. I tried the same way as shown in the example, but still having same issue. The system becomes unresponsive when it hits NRF_ADC->TASKS_START = 1. And I saw that without sd_nvic_SetPriority(ADC_IRQn, NRF_APP_PRIORITY_LOW); ADC doesn't work. What happens to the priority of ADC_IRQn if I skip sd_nvic_SetPriority(ADC_IRQn, NRF_APP_PRIORITY_LOW); ?

[RK]

'System becomes unresponsive'. No it doesn't, it's somewhere doing something, probably in a fault handler or an error handler. Hit the break button in the debugger and find out where you are, that may give us a better idea what's happening.

[Kevin Choi]

Thank you for the comment RK. You are right. 'unresponsive' was a bad word choice. My apologies. Unfortunately, I am not able to use debugger on the design that im working on. The first thing I would do was what you said if i had debugger. All I have for debugging is three LEDs. I have lines of code that works on nrf51 Development Kit, but it is not doing same thing on my design.

[Stefan Birnir Sverrisson]

If you have different behavior on your custom board than on the nRF51-DK board with the same firmware, then it must be a hardware issue. Do you have any firmware working on your custom PCB yet, or is it just related to ADC operation? Does your custom board have third revision nRF51?