Been using a USB Multi Tech modem with Verizon through my Pi that I was given to test. Got through some issues but have it connecting now, whats odd is I went through all the updates for the Pi and what not. If I use a year old image my AT shutdown command for the modem works great and merely resets the modem only with no Pi change.
Since the updating to current whenever I send the AT command to shutdown the modem (I have a small script to watch teh ppp connection for auto reconnect. If its sees no PPP connection it then resets the modem as I was having issues with busy line, then trys to redial.)
is the AT command, since I have updated when I run my script or that command only from Minicom it resets the entire device. I was thinking maybe something to do with hotplug issues but I have tried the upgraded cap and still remains the same. The modem pulls power seperatly I have a 5v 4amp PSU that splits to power the pi and modem on a shared line.
Curious if anyone has a thought to why the entire system restarts itself when before updating it works all day long.
EDIT: measured boards current while running the command and voltage stays around 5 so it seems that it is not a current drop.