https://devzone.nordicsemi.com/f/nordic-q-a/27742/twi-scl-clock-irregularityI&#39;m noticing some irregularity on the SCL line coming from my Nordic 52832. I&#39;ve attached a Saleae logic trace here. What are the potential causes for this type of behavior? ST54_init_I2C_trace.logicdataen-USTelligent Community 13Fri, 01 Dec 2017 09:55:00 GMThttps://devzone.nordicsemi.com/thread/109466?ContentTypeID=1Fri, 01 Dec 2017 09:55:00 GMT137ad170-7792-4731-bb38-c0d22fbe4515:93717749-ef4c-44bc-a954-75b4252344f8Sigurd<p>We suspect that the pullups are too weak. We have answered the duplicate question in MyPage(case id 40611).</p> <p>Answer from MyPage:</p> <blockquote> <p>I was looking at the TWI trace data, and it looks like the pull-ups on the SCL and SDA lines are too weak for 400 kHz. Are you using the internal pull-resistors? These will limit the frequency greatly, and we recommend that you use external pull-up resistors in the range of 2.2k to 3.9k in order to use 400 kHz mode. For the 100kHz mode, the internal pull-ups (nom. 13k) will work without issues.</p> </blockquote><div style="clear:both;"></div>