Probs with A6 GSM module and Arduino

G’day all, I have 2 of these modules and neither works as expected. I am testing with the sketches on DFRobots website.

The first does not respond at all and the 2nd shows backward ? characters in the Arduino serial monitor. I think this is a character for decimal 255 which is not what I would expect in response to AT commands.

I’ve read that these module can be quite current hungry and at the moment I have access only to USB power. I’m going to collect a 3A psu tomorrow so will update this after that.

If you’ve had any experience with these I’d love to read how you got on.

Mike H

Problem resolved. The GSM module does indeed chew through the juice. A 3A psu has fixed the problem.

Mike H


Neat, glad to hear you got it working, Mike!

Well, the initial problem was simply the baud rate for the modem. You may find as I did that it defaults to 115200, not 9600. When you set the serial monitor to 115200 you will get a lot of rubbish (corrupted) characters, so I suggest you set it to run at 9600.

I still have a problem though. It will NOT send an SMS or make a phone call. This is extraordinarily frustrating. I’d love to hear from anybody with similar issues.

Hi Mike60090, I have the same problem with an A9G module. I have an Optus prepaid SIM installed which it is happy with (AT+cpin? => +CPIN:READY) but it won’t register on a network (AT+CREG? =>
+CREG: 1,2).
Did you end up solving your problem? Sounds the same as mine.

Hi All,

Very sorry - this one has slipped passed our check gate! Our system auto imported this product from DFRobot’s listing. This is a 2G device and there’s no 2G networks in Australia anymore. The frequencies used for GSM have been reallocated for 4G standards.

The A9G will still of course work as a GPS as per Leigh’s review, but not as an IoT modem. The A9 is more or less useless in Australia.

We’ll send an email out to all affected customers ASAP!