Twi interface

[yashchabria]

Which is the preferred way,  accessing sensor via the TWI

1) NRFX_Driver

2) TWI HAL 

what options do I need to select in the SDK_CONFIG.h to use the twi_driver api. 

[yashchabria]

Also, what does this imply  'NRF_DRV_TWI_INSTANCE_0' was not declared , I have enabled TWI in sdk_config.h

[yashchabria]

I sorted the 'NRF_DRV_TWI_INSTANCE_0' issue with sdk_config.h

[Simon]

The "abstraction flow" for accessing the twi peripherals (and the other peripherals) in SDK 15.x.x is the following:

TWI driver (Legacy layer) → TWI driver (NRFX)   → TWI HAL

• The Legacy TWI driver is a glue layer that remaps to the NRFX functions (see this link for an explanation how it works)
  • It is not pure remapping, some functionality is added in between 
• The NRFX TWI driver accesses the HAL driver, and makes it more simple to use the TWI HAL 
• The TWI HAL accesses the TWI registers directly

Unless you need complete control and flexibility of what you are doing I would not recommend you to use the TWI HAL, as it requires a lot of extra work. Regarding the choice of driver, there has been some discussion about this. However, I would recommend you to use the TWI driver, since all the examples in the SDK uses this and I think it will be less to troublesome. Also the legacy driver is more compatible with BLE functionality.

In the sdk_config.h file, you should use the legacy definitions and ignore the NRFX definitions, as explained here.

Best regards,

Simon