TWI master and slave on the same port

[Dominik Eugster]

Hi

I am using the nRF52840 with an external sensor which I need to config (nRF is the master). after this, nRF is acting like a I2C slave (twis) and i like to trigger an interrupt as soon as the sensor is sending some data (sensor = master, nRF = slave) To read out values from the sensor, nRF will change to master, sensor to slave.

nRF is always the master or the slave, not both at the same time of course.

Master communication is running, but as soon as I enabled the twis in the SDK config, I got the Error of an already defined IRQ:

multiple definition of `SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1_IRQHandler;

what I found in the DevZone is that nRF is using the same IDs and it would be possible to solve this with the function

nrfx_err_t nrfx_prs_acquire(void       const * p_base_addr,
                            nrfx_irq_handler_t irq_handler);

Is tis correct? How do I have to implement this function to solve the Error?

Do you have an example which shows how should this be implemented?

Thanks a lot

[Kenneth]

Have you check if it's possible to setup the sensor to always be the slave, and instead having an irq signal to inform the nRF52 when to poll the slave for data? Reason for asking is that this might reduce current consumption quite a lot, since I expect having twi slave enabled all the time will be quite power intensive (~1mA).

Kenneth

[Dominik Eugster]

No, this is not the solution I'm looking for. The current consuption is ok (mains powered application) I need the IRQ and don't like to poll, this is not possible in my solution and not a clean code in my opinion.

Is there any example to do this?

[Kenneth]

I could not find any example, but looking at the answer here and documentation here. And then also looking the the source code for both nrfx_twim.c and nrfx_twis.c I can find that you should only need set NRFX_PRS_ENABLED and NRFX_PRS_BOX_n_ENABLED (where n is the shared instance).

Then make sure that you always call uninit() of the previous shared peripheral instance before caling init() of the new shared peripheral instance, then this should work out of the box (literally and hopefully).

Kenneth

[Dominik Eugster]

ok, but should I use the complete I2C (TWI) driver with the NRFX functions or the old nrf funcions?

[Kenneth]

It doesn't matter, there is a glue layer between nrf and nrfx (so nrfx is used in both cases):

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/nrfx_migration_user_guide.html 

Kenneth