EHS5-E keeps resetting until USB is plugged | Telit Cinterion IoT Developer Community
April 1, 2017 - 9:48am, 2127 views
We have a softwareless EHS5-E (ARN14) on a PCB developed by us. EHS5-E keeps resetting itself in a 3-5 sec rhythm, see console screen capture attached.
The last type out was ^SYSLOADING, after which restart occurred again.
Nevertheless if we connected the EHS5-E to an USB port, the resetting stopped immediately and the EHS5-E began to behave normally. After we pull out the USB most devices, start to reset repeatedly again. Some don't!
Not all PCBs do exhibit this bad behaviour, only cca 15%, bad enough. I read in the documentation that, when USB is activated, the module is prohibited to enter the SLEEP state.
But I don't have a clue what exactly happens and who is to blame for it. Is it my PCB or the schematic to blame? Did it happen to you?
By the way, it's no April Fool's Day...
Very strange coincidence. Without USB module consumes less power so it would be more obvious if it reseted with USB than without. Nevertheless it looks like the first thing to blame is your hardware but it's of course too early to judge now. The module is probably soldered to the board so it would be difficult to swap with another board for test. Have you tried to do measurements of any lines?
Have you been preparing your project in accordance with the hardware description document and the reference design document here https://iot-developer.thalesgroup.com/documentation/example-schematic-eh... ?
Have you installed any software on the module, made any configuration or is all in factory default state? Please paste AT^SCFG?, AT^SPOW?, AT&V replies. Does it happen right after booting and each time or only occasionally or after some time of functioning normally?