HL7800 periodically reconnects

IoT Modules
1

I don’t know if this is normal or not. About 1 or 2 times an hour the unsolicited message that +CREG status is 0 (disabled registration) or 4 (unknown) and automatically reconnects. Sometimes it takes several seconds to reconnect. I had set CREG=2. That reports the same cell tower is connected to each time. Identifying <lac> and <ci> below are replaced with x’s. The output below is from about 2 hours duration.

+CREG: 0
+CREG: 2
+CREG: 5,“xxxx”,“xxxxxxxx”,7
+CREG: 4
+CREG: 5,“xxxx”,“xxxxxxxx”,7
+CREG: 4
+CREG: 5,“xxxx”,“xxxxxxxx”,7
+CREG: 4
+CREG: 5,“xxxx”,“xxxxxxxx”,7
+CREG: 4
+CREG: 5,“xxxx”,“xxxxxxxx”,7
+CREG: 0
+CREG: 2
+CREG: 2
+CREG: 0
+CREG: 2
+CREG: 5,“xxxx”,“xxxxxxxx”,7

2

@sales

So its a bit of a difficult question to answer, as the 4 could be output because of PSM power save mode. Without a log file (layer 3 from the debug UART) its hard to say. If you send the following then it will give a bit more background.

ati
at+cgmr
at+cgdcont?
at+csq
at+cpsms?
at+cops?
at+cops=?

Also getting the responses (including the +CREG ones) with time stamps can help diagnose what might be wrong.

Regards

Matt

3

I haven’t enabled any power saving modes. The system responds immediately to any AT command.
I previously upgraded the firmware.
I will bring out the other UART interfaces in the next PCB revision for debugging.
It seems that RSSI signal strength is low.
I would like to find the technical resource for the log file interface.

Commands output:

HL7800-M
OK
HL7800-M.4.4.6.0
OK
+CGDCONT: 1,“IP”,“xxxxxx.xxx”,0,0,0,0,0,0,+CGDCONT: 2,“IPV4V6”,0,0,0,0,0,0,
OK
+CSQ: 6,99
OK
+CPSMS: 0,“11100000”,“11100000”,“00101100”,“00001010”
OK
+COPS: 0,0,“xxxxxxxx”,7
OK
+COPS: (1,“AT&T”,“AT&T”,“310410”,7),(0,“313100”,7),(3,“Verizon”,“Verizon”,“311480”,7),(0-3),(0-2)
OK
+CESQ: 99,99,255,255,6,13
OK

4

@sales

So comments I would make are.

  • Not great signal strength but its workable.
  • PSM is off so the unit is not going into it.
  • I suspect that the network/the back end infrastructure is causing the unit to come on and off it. Again a layer 3 log file from the debug port would help here.

Regards

Matt