https://devzone.nordicsemi.com/f/nordic-q-a/56706/add-support-for-i2c3-in-sdkfor the i2c_3 to work the following is needed to modify the SDK. nrf/subsys/spm/Kconfig ``` config SPM_NRF_TWIM3_NS bool &quot;TWIM3 is Non-Secure&quot; default y ``` and spm.c ``` #ifdef NRF_TWIM3 PERIPH(&quot;NRF_TWIM3&quot;, NRF_TWIM3, CONFIG_SPM_NRF_TWIM3_NSen-USTelligent Community 13Mon, 20 Jan 2020 07:27:49 GMThttps://devzone.nordicsemi.com/thread/229750?ContentTypeID=1Mon, 20 Jan 2020 07:27:49 GMT137ad170-7792-4731-bb38-c0d22fbe4515:155e6eeb-d34a-4c43-9b7e-56f796aa8322H&#229;kon Alseth<p>Hi,</p> <p>&nbsp;</p> <p>SPI*, TWI*, and UARTE* are all shared peripherals, meaning that SPIM0 and TWIM0 cannot be enabled at the same time. You&#39;ll then have to use for instance SPIM0 and TWIM1.</p> <p>Since SPIM3 is added to the spm module, you should be able to use TWIM3 as well:</p> <p><a href="https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/subsys/spm/Kconfig#L155">https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/subsys/spm/Kconfig#L155</a></p> <p>&nbsp;</p> <p>Shared peripherals can be identified here, where their base address is the same:</p> <p><a href="https://infocenter.nordicsemi.com/topic/ps_nrf9160/memory.html#topic">https://infocenter.nordicsemi.com/topic/ps_nrf9160/memory.html#topic</a></p> <p>&nbsp;</p> <p>Kind regards,</p> <p>Håkon</p><div style="clear:both;"></div>