target_connected() return error status

[tianxiaoMCU]

1. At the beginning，target_connected() return True；
2. then disconnect all cables between jlink and target（connection between PC and JLink still exist）；
3. target_connected() still return True；

[hkpeprah]

I think we'd have to try a debugging command of some sort (that would always succeed if the target is connected), and check that it fails in order to determine if the cable was un-plugged, as if the method returns true, it believes the target is still connected.

[JeremiahGillis]

I was surprised when target_connected() always returned True upon a J-Link cable disconnect or when the device was unplugged. I wonder how Segger intended this to work...

What I did, which only works with self powered device (not powered via J-Link), was to monitor VTarget in hardware_status. I have a worker thread watch this and trigger a target disconnect when the voltage is < 0.25 V. I haven't had any issues with this method.