https://devzone.nordicsemi.com/f/nordic-q-a/22974/can-nrf52-sdk-twi-master-write-a-series-of-registersI want to save precious CPU cycles by writing 40 i2c (TWI) registers in one shot. Can I somehow set up the TWI master to write 40 registers (each 16-byte address with 8-bit data)? Further, can this be done for two slave devices with two different slaveen-USTelligent Community 13Thu, 22 Jun 2017 10:18:32 GMThttps://devzone.nordicsemi.com/thread/90393?ContentTypeID=1Thu, 22 Jun 2017 10:18:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4fc94d5d-0a85-4765-ab51-e6634f29969bJ&#248;rgen Holmefjord<p>Hi,</p> <p><a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v13.0.0/group__nrf__drv__twi.html?cp=4_0_0_6_8_24_3_28#ga2c5ea8408254dfa9cbff55dbee171a95"><code>nrf_drv_twi_tx</code></a> take a pointer to the data, <em>p_data</em>, and a <em>length</em> parameter indicating the lenght of the data. The transfer function support a length up to 256 bytes. The code snippet in the <a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v13.0.0/hardware_driver_twi.html?cp=4_0_0_2_16_1#hardware_driver_twi_basic">TWI master documentation</a> shows how this is done. It is also possible to trigger a transfer directly from RAM using <a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v13.0.0/hardware_driver_twi.html?cp=4_0_0_2_16_2_0#hardware_driver_twi_ppi">EasyDMA and PPI</a>.</p> <p>It is not possible to transfer to multiple devices connected to the same bus simultaneously, but you can initialize <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/twim.html?cp=2_1_0_32_7#unique_1822381857">both TWI instances</a> available on the nRF52832, and start one transfer on each instance.</p> <p>You will have to check the datasheet of the device you are interfacing, if it support this method of writing.</p> <p>Best regards,</p> <p>Jørgen</p><div style="clear:both;"></div>