I2C interrupt while softdevice enabled

[Matthias]

Hello,

i'm sorry for asking again, but i read nearly all threads about I2C and didn't get any answer yet.

I want to use the interrupt to control the I2C sequences and safe energy (instead of using while loops)

I replaced the NRF_TWI1->INTENSET.... with sd_app function below... If i start a transmition it never goes into the handler or generates an event. can anybody tell me why?

Is the NVIC_ENABLEIRQ right to use? in the end i have the usual handler.

	void init_TWI1()
{
	//I2C Init start
uint32_t err_code;
NVIC_EnableIRQ(SPI1_TWI1_IRQn);
NRF_GPIO->PIN_CNF[1] = 0x60C;
NRF_TWI1->PSELSCL = 0;	//P0 als SCL
NRF_TWI1->PSELSDA = 1;	//P1 als SDA      
NRF_TWI1->FREQUENCY = 0x06680000;	//Frequenz = 400kHz

err_code = sd_ppi_channel_assign(0,
																		&(NRF_TWI1->EVENTS_BB),
                                 &(NRF_TWI1->EVENTS_TXDSENT));

	
	
		
//I2C init end
}



	void SPI1_TWI1_IRQHandler(void) 
{
	if(NRF_TWI1->EVENTS_RXDREADY != 0)
	{
		NRF_TWI1->EVENTS_RXDREADY = 0;
	}
		if(NRF_TWI1->EVENTS_TXDSENT != 0)
	{
		NRF_TWI1->EVENTS_TXDSENT = 0;
	}
		if(NRF_TWI1->EVENTS_BB != 0)
	{
		sd_app_evt_wait();
		NRF_TWI1->EVENTS_BB = 0;
	}

}

[mnhs]

Try to use sd_nvic_enableIRQ(SPI1_TWI1_IRQn); instead of "non-sd" NVIC_EnableIRQ(). By default all the interrupt priorities are set to 0 (highest priority) which is reserved exclusively for SoftDevice. Thus, the SoftDevice may become unstable. Alternatively, you can try to set the priority of SPI1_TWI1_IRQn interrupt to 1 - 3.

I am also not sure if you can put the sd_app_evt_wait directly into interrupts. It should be in the main cycle. When the handler ends it job, it jumps back to the main cycle and goes to sd_app_evt_wait.

[Krzysztof Chruscinski]

If NRF_TWI1->INTENSET=... is removed then you have disabled peripheral interrupt and it will never go to nvic. There are two stages of interrupt control: in the peripheral using INTENSET/INTENCLR you enable particular peripheral events as interrupts and then in NVIC you control general interrupt from this peripheral.

It is recommended to access nvic using softdevice API. As TWI is not used by softdevice you can access TWI registers directly.

As mnhs mentioned, it is vital to set proper interrupt priority (1 or 3, you can also use app_irq_priority_t from app_util_platform.h in SDK)