SIMCOM A7670G Disconnecting, reconnecting, and failing to receive/send SMS in a few hours.

[Aaron2]

I am working with A7670G modules to replace SIM800L in agriculture projects. My question is, testing the A7670G, everything operates perfectly on startup for random short time periods(1hr, 3hr, 10 hr), then suddenly when an event occurs the A7670G does not (respond) read SMS or send SMS with a given input from MCU. The direct serial output from module preceding this failure includes:
+CGEV: NW PDN DEACT 1
+CGEV: NW REATTACH
+IMSUEEVENT: 0,7
+CGEV: EPS PDN ACT 1
+CGEV: NW PDN DEACT 1
+CGEV: NW REATTACH
+IMSUEEVENT: 0,7
+CGEV: EPS PDN ACT 1

Setting idle overnight, there may be 3-5 of these sets of items:
+CGEV: EPS PDN ACT 1
+CGEV: NW PDN DEACT 1
+CGEV: NW REATTACH
+IMSUEEVENT: 0,7

Then, sending an SMS to the A7670G may take 20 minutes to get a response.

The registration status is: +COPS: 0,2,"310260",7. Signal strength is very good. The flashing network indicator never stops and the module always responds to AT commands. The previous SIM800L modules I used were very reliable and just worked. What could be causing this behavior?

Any advice greatly appreciated.

 

[aliarifat794]

An unstable power supply can cause such issues. Check the voltage and current ratings of your power supply.

 

[KlausST]

An unstable power supply can cause such issues.

You may olso check them with a scope.
And you should check for floating inputs.

Klaus

 

[Aaron2]

I spoke to John Faucher, the Simcom rep in California US, and I was educated on the Simcom A7670G(A-Series) vs the SIM7670G(SIM-Series). He explained that the "A" prefix (like A7670G) means the module has the ASR Microelectronics baseband chipsets that are not certified for use in the United States, and will likely be shut off completely in 3 months. But the "SIM" prefix (like SIM7670G) Uses the Qualcomm baseband chipset and is certified/approved for use in the US. The SIM7600 boards we are testing now seem to never disconnect or fail to send or receive SMS/Data. Ordering a SIM7670G for testing next(best price).

From SIM7670G FCC certification docs.