https://devzone.nordicsemi.com/f/nordic-q-a/81006/i2c-bus-spikesHi Team, These are the SDA and SCL lines of nRF52832 connected to a sensor. the clock frequency defined in the code is 400 KHz, but its coming as 200 KHz on oscilloscope. I think this is due to the weak internal pull up resistors. I believe this shoulden-USTelligent Community 13Mon, 25 Oct 2021 11:54:25 GMThttps://devzone.nordicsemi.com/thread/335712?ContentTypeID=1Mon, 25 Oct 2021 11:54:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:48595986-7d82-4610-b9de-10853fc17498H&#229;kon Alseth<p>Hi,</p> <p>&nbsp;</p> [quote user=""]1) I know that the poor shape of the signals are due to weak internal pullup resistors. <span style="text-decoration:underline;">Can I ask you if this poor shape can cause reading wrong data ?</span> For the first square (marked red), shows that the data is changing during the rising edge of clock. We are currently reading correct values, <span style="text-decoration:underline;">but is this prone to errors ?</span>&nbsp;[/quote] <p>Yes, this can cause errors in communication. You should consider either going to 100 kHz mode, or add stronger pull-up resistors.</p> [quote user=""]2) I sometimes notice noise on SDA line as shown in the above figure. Is it okay to notice such spikes during the negative cycle of clock ? Can this cause wrong data ? How can I avoid this ?[/quote] <p>You should add proper pull-ups and redo the scoping. This&nbsp;could be a edge detection on the slave side (ie. ACKing of the packet).</p> <p>&nbsp;</p> <p>Kind regards,</p> <p>Håkon</p><div style="clear:both;"></div>