NRF52: Legacy TWI Driver not linking on SDK15 (undefined reference)

Question

Hello,

I am trying to use the Legacy TWI Driver in SDK 15. I have setup my my sdk_config.h file to remove all references to NRFX (New TWI Driver). Only enabling the "nrf_drv_twi" driver via CMSIS configuration wizard, unfortunately the linker fails to find reference to many of the TWI functions. As referenced here: https://devzone.nordicsemi.com/f/nordic-q-a/34317/undefined-reference-to-nrfx_twi_tx/132496 ; there are quirks in associating the older legacy functions. I have also experimented with combinations of enabling the NRFX driver, enabling TWIM, enabling EASY DMA (legacy TWIM), etc. to no avail.

Compiler Output:

Linker Error

Here is my sdk_config.h file:

sdk_config.h

Any ideas on how to resolve this would be appreciated.

Thanks

Jørgen Holmefjord · Accepted Answer

Hi, 
 Did you include the source files in your project? Note that you need to add the following files to you project, in addition to enable the modules in sdk_config.h: 
 
 integration
rfx\legacy
rf_drv_twi.c 
 modules
rfx\drivers\src
rfx_twi.c / nrfx_twim.c 
 
 Best regards, Jørgen

haxxa · Answer

Based on your guidance, I investigated further and realised my preprocessor directories were inconsistent. I have now got it working. I really should have picked up on this. Sometimes it's the really basic errors you overlook.

Thanks for your help.