https://devzone.nordicsemi.com/f/nordic-q-a/76545/lpuart-nrf9160---nrf52840Hi, we have troubles to use 4wire NRF LPUART between nRF52840 (client) and nRF9160 Serial LTE Modem app (server). We use v1.5.1 of nRF Connect SDK. For nRF9160 we added CONFIG_SLM_CONNECT_LPUART and modified slm_at_host.c. nRF9160 prj.conf: en-USTelligent Community 13Mon, 21 Jun 2021 13:59:00 GMThttps://devzone.nordicsemi.com/thread/316295?ContentTypeID=1Mon, 21 Jun 2021 13:59:00 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5b3178fc-754e-44f7-b8b5-855c2ebdc822Carl Richard<p>Hello,&nbsp;Michal!<br /><br />Thanks for reaching out. There are known issues with the LPUART driver on v1.5.1 of NCS, and several fixes should be present in v1.6.0-rc2. I will try to dig up the specific commits, but ideally you should move to the new release and then I can help you resolving the issues you have there.<br /><br />I just tested disabling RTT when build SLM on v1.6.0-rc2 without any issues. What kind of errors are you getting?<br /><br />Best regards,<br />Carl Richard</p><div style="clear:both;"></div>