How to block the code while interrupts are executing?

[sowmya]

Hello,

I am working with S110 stack and the custom application. I wanted to use the ADC driver with blocking and interrupts enabled. But the application is blocking and it blocked the ISR thereby I am not getting ADC interrupt too. This is the configuration snippet:

void adc_init(void)
{

NRF_ADC->CONFIG = (ADC_CONFIG_EXTREFSEL_None << ADC_CONFIG_EXTREFSEL_Pos) | 
                  (ADC_CONFIG_PSEL_AnalogInput3 << ADC_CONFIG_PSEL_Pos) | 
                  (ADC_CONFIG_REFSEL_VBG << ADC_CONFIG_REFSEL_Pos) | 
                  (ADC_CONFIG_INPSEL_AnalogInputOneThirdPrescaling << ADC_CONFIG_INPSEL_Pos) | 
                  (ADC_CONFIG_RES_10bit << ADC_CONFIG_RES_Pos);

NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Enabled;
NRF_ADC->INTENSET = ADC_INTENSET_END_Msk;
NVIC_SetPriority(ADC_IRQn, NRF_APP_PRIORITY_LOW);
NVIC_EnableIRQ(ADC_IRQn);
}

Blocking function is:

Conv_Completed = false;
NRF_ADC->TASKS_START = 1;
while(Conv_Completed == false);

ADC ISR is:

void ADC_IRQHandler(void)
{
uint32_t ADC_result;
NRF_ADC->EVENTS_END 	= 0;
NRF_ADC->TASKS_STOP 	= 1;

ADC_result				= NRF_ADC->RESULT;
NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Disabled;
Conv_Completed = true;
}

Can any one tell hoe to use blocking code ? I am not interested in using Scheduler since it will block the application events until the scheduler tasks are complete.

Regards,
Sowmya

[Einar Thorsrud]

In your case, you must make sure that the priority of ADC_IRQHandler() is higher than the priority where you wait for the Conv_Completed flag. How do you call that piece of code? As you have this problem, it seems it's called from a interrupt context. Either you should try to call it from the main context (effectively lowering its priority), or you need to increase the priority of ADC_IRQHandler().

[sowmya]

Thank you for the reply. Yes I called it from main but still interrupt was not hitting and it was in the blocking statement while(Conv_Completed == false);. How to set the priority of the variable?

Update: The code snippet will be like this:

void read_adc()
{
 Conv_Completed = false;
 NRF_ADC->TASKS_START = 1;
 while(Conv_Completed == false);
 }

Yes previous I was calling from timer isr. Now I changed and calling from main, but still interrupt is not coming.

[Einar Thorsrud]

If you execute the code in this comment from main() somehow rather than a interrupt, I do not see what the problem can be. You could always try to change the priority of ADC IRQ to NRF_APP_PRIORITY_HIGH, though it should not be needed. What is the state of the ADC peripheral after it has been started? Could you check with a debugger?