Add support for i2c3 in SDK

[Sashi]

for the i2c_3 to work the following is needed to modify the SDK. 

nrf/subsys/spm/Kconfig

```

config SPM_NRF_TWIM3_NS

bool "TWIM3 is Non-Secure"

default y

```

and

spm.c

```

#ifdef NRF_TWIM3

PERIPH("NRF_TWIM3", NRF_TWIM3, CONFIG_SPM_NRF_TWIM3_NS),

#endif

```

Can this be added to the stock SDK?  

for that matter, other configurations should be added as well, such as SPI 1 etc..  is there a reason this is not added in the SDK?

[Håkon Alseth]

Hi,

 

SPI*, TWI*, and UARTE* are all shared peripherals, meaning that SPIM0 and TWIM0 cannot be enabled at the same time. You'll then have to use for instance SPIM0 and TWIM1.

Since SPIM3 is added to the spm module, you should be able to use TWIM3 as well:

https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/subsys/spm/Kconfig#L155

 

Shared peripherals can be identified here, where their base address is the same:

https://infocenter.nordicsemi.com/topic/ps_nrf9160/memory.html#topic

 

Kind regards,

Håkon