https://devzone.nordicsemi.com/f/nordic-q-a/2169/i2c-bus-with-no-external-pull-upHi, We are using nRF51422 in our project and we observe a strange thing, that even there is no external pull up resistors, the I2C communication using the built-in TWI port is still working fine, I would like to check with you whether this is the caseen-USTelligent Community 13Fri, 02 May 2014 05:32:49 GMThttps://devzone.nordicsemi.com/thread/9179?ContentTypeID=1Fri, 02 May 2014 05:32:49 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6b9a492a-eb14-401b-a341-cb4387ddad56Antonio<p>Are these internal pullup present even when the nRF51422 is sleeping?</p> <p>Thanks,</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/9178?ContentTypeID=1Wed, 09 Apr 2014 13:26:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:16ee9da5-35ac-49e4-b289-cbe97671114eJoseph<p>Hi Peter, you are right. Thank you!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/9177?ContentTypeID=1Wed, 09 Apr 2014 12:01:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ae90b97d-c16d-4653-9aee-97c3465d786aPetter Myhre<p>Hi Joseph</p> <p>The nRF51422 supports internal pullups for use with the TWI module. Unmodified, our hardware TWI driver uses internal pullups. I would examine how the GPIOs are configured to find out.</p> <p>Please let me know if there is anything else.</p><div style="clear:both;"></div>