NRF/NRFX TWI manager configurations & NRFX_TWI0_INST_IDX undeclared

Have you tried to set TWI0_ENABLED and TWI_ENABLED to 1 (not NRFX_TWI..), I think that will solve your problem.

The reason for this is that NRFX_TWI0_ENABLED is defined as follows (in the file apply_old_config.h):

#undef NRFX_TWI0_ENABLED
#define NRFX_TWI0_ENABLED   (TWI0_ENABLED && !TWI0_USE_EASY_DMA)

Best regards, Simon

I have the same issue. I'm trying to use the "nrfx_twim.h" library and functions in the ble_app_hrs example. I am getting the same error. I have NRFX_TWIM_ENABLED = 1, NRFX_TWIM0_ENABLED = 1, THen I set, TWI_ENABLED = 1 and TWI0_ENABLED = 1. I can't figure out why if I am using the new libraries and functions I should need the apply_old_config.h file. I also can't figure out why that section of code in nrfx_twim.h is failing. I added debuggers in main.c and the output confirms the asserted definitions above are correct. What am I missing? BTW, I am trying to compile with GCC. I switched the functions from  nrf_drv to nrfx_ because it won't compile in GCC, although it did compile in Keil with nrf_drv_

Update: I guess something else in the sdk_config file is forcing apply_old_config, so I have to go back to nrf_drv_ functions--but I am back to getting "undefined reference to 'nrfx_twi_tx" and "nrfx_twi_rx".  In sdk_config.h iI have only set TWI_ENABLED  and  NRFX_TWI_ENABLED  since that was in the logical statement and it still failed. Then I put in a print line to see if TWI_PRESENT was defined and it was. So I'm confused as to why this redefinition in  is not executing and the nrfx_twi_tx function is not defined. Way down in nrfx_twi.h where this function is defined I ran the same NRFX_CHECK error check and it passed. I can muck with nrfx_twi.h and get errors so I know it is being called by nrf_drv_twi.h and TWI_PRESENT is defined. So why are they functions being defined?  

Looks like my nrfx_twi.c function is not being compiled--I can muck with it but it doesn't do anything. I need to figure out how to modify the makefile to link it.

Update: Solved. For some reason the Keil project was able to find and link nrfx_twi.c and nrf_drv_twi.c but I had to manually add them to the makefile for gcc.

UPDATE
I get TRUE finally when I do the opposite, actually. I took another shot at purging every non-nrfx mention of TWI from the sdk_config and now it gives me both true and compiles as intended! I must have left something behind last I tried this. THANK YA'LL for the help :D !!
 

Gave it a shot with
TWI0_ENABLED 1
TWI0_USE_EASY_DMA 1
with the nrfx_twi definitions both present and completely striped from the sdk_config. Seems like it simply overwrites if it's already present/defined, but at this point I'm trying everything. Neither method fixes this unfortunately.

so nrfx_twi.c is definitely being brought in and compiled; Added  a few tests in here as well to see what's going on...
 

#if NRFX_CHECK(NRFX_TWI_ENABLED)
    #error "NRFX_TWI_ENABLED TRUE"
#else
    #error "NRFX_TWI_ENABLED FALSE"
#endif

With the above I'm getting NRFX_TWI_ENABLED FALSE on compile.
Also tried massaging that into

#if NRFX_TWI_ENABLED==0
    #error "NRFX_TWI_ENABLED FALSE"
#else
    #error "NRFX_TWI_ENABLED TRUE"
#endif

And still, FALSE.

The result's the same
No matter what I change, add, or remove, NRFX_TWI_ENABLED is 0

Glad to hear that you finally made it work. Please ask if you enter any more problems.

Cheers, Simon