I am getting the following error when trying to connect via ppp. My configuration is an rPi zero W, connected via USB. GPS stream to rPi is working great. Here is the error:
Dec 15 23:39:57 automocpi chat[1841]: AT+CGDCONT=1,”IP”,”hologram”^M^M Dec 15 23:39:57 automocpi chat[1841]: ERROR^M Dec 15 23:39:58 automocpi pppd[1800]: Device ttyACM0 is locked by pid 1839