https://devzone.nordicsemi.com/f/nordic-q-a/37396/twi-causes-nrf_error_internal-and-fatal-errorI have a hardware with NRF52832 module and successfully used the example twi-scanner to locate my I2C peripheral. I copied these parts over: My own code produces this error on the line APP_ERROR_CHECK(err_code); in m41t62_test : &lt;info&gt; TWI: Transferen-USTelligent Community 13Mon, 13 Aug 2018 10:48:31 GMThttps://devzone.nordicsemi.com/thread/143907?ContentTypeID=1Mon, 13 Aug 2018 10:48:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:431d3c75-d6be-49e1-aea1-50f16ee59908Bastian<p>Hi, I have external pullups on the lines. I set the GPIO to input no pull and now it works. Toggeling the SCL pin is not neccessary though. Thank you for your help</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/143813?ContentTypeID=1Sun, 12 Aug 2018 12:20:23 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3ad43df3-d50c-4465-95e9-6ed697064e0cAndre<p>Error 3 usually means something is pulling the SDA line low.&nbsp; Verify you are using the correct pins. Are you missing some pull ups? If you have no external pull ups mounted, try</p> <p><pre class="ui-code" data-mode="c_cpp">twi_config.scl_pull = NRF_GPIO_PIN_PULLUP; twi_config.sda_pull = NRF_GPIO_PIN_PULLUP;</pre></p> <p>If that does nothing, then try to determine if the peripheral might be pulling the sda line low. In order to recover from this condition, uninitialise the twi, configure the SCL pin as output, toggle it 16 times with some delay, and re-initialise the twi and try again.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/143803?ContentTypeID=1Sat, 11 Aug 2018 21:05:59 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4a979960-a674-427a-9ced-7105e7b7b104Bastian<p>Using the twi-scanner example I can see data running along the pin with the scope. Using the code in my application does nothing on the pin.</p><div style="clear:both;"></div>