TWI Init/Uninit Driver Bug

[Michael]

I have an application that uses many TWI buses, on many pins of the nRF51. I handle this by initializing/uninitializing a single TWI bus for different transactions. I ran into the issue where the TWI driver would get stuck in "transfer_in_progress" every once in awhile while using SDK v9.0. When debugging I could see that the "transfer_in_progress" flag is only cleared in the interrupt, so it was impossible to recover from a stuck "transfer_in_progress" after a disable/uninit. To resolve my issue I added:

m_cb[p_instance->instance_id].transfer.transfer_in_progress = false;

to the

void nrf_drv_twi_disable(nrf_drv_twi_t const * const p_instance)

function. I am probably circumventing some terrible race condition that I have created, but with this change my tests have done thousands of successful TWI transactions. The original author of the driver might have a better idea how to prevent the failure. I dislike maintaining my own driver files because it prevents me from taking SDK updates wholesale, it would be nice to have a fix in the SDK. Maybe this has been fixed in v10.0 or v11.0?

[tesc]

Hi,

I do not know if there is still a similar issue in the current SDK, but from what I can see the TWI driver is completely rewritten for SDK 11.

[Carl]

I ran into kind of the same problem with SDK v11 (nRF52).

In the beginning I initialize and enable TWI, tx and rx works fine. After deinitializing and reinitializing (to change the frequency), tx does not work anymore.

It's stuck in function twi_tx_start_transfer(...) of driver nrf_drv_twi.c in the loop while(twi_transfer(...)) at line 450.

[Kenneth]

Hi,

The intended procedure to start any I/O peripheral is to: CONFIGURE->ENABLE->START And in the reverse order to stop any I/O peripheral: STOP(wait for event)->DISABLE(->RECONFIGURE)

All HW modules is based on this principle.

If the I/O peripheral use a shared reseource with another peripheral also used by the application, then you need to carefully check all configuration settings when it is failing, in case you depend on a default value that might have changed.