SEROUT2 to GSM Modem

[tommyers]

as an addition to the previous post.........

I have just connected my PIC hardware to my serial lead back to my PC and then run hyperterminal. The commands which I think I am generating by the PIC are being received ok by hyperterminal!

Cheers

Tom

[frustrator]

Mate that's a good one.

The only thing I can think of at the moment is to make sure all the cables to the modem are wired around the correct way.

Is there any data the computer sends first via hyperterm to initialize the modem?

Please let me know how you go with this...

Chris

[tommyers]

Hi Chris,

Thank you for your post.

I have since solved the problem which I reported. I had already tried your suggestion, since there was two way communication between the modem and hyperterm / PIC because I were receiving acknowledgements from the modem to some commands and error messages from others.

The commands which gave me errors were those which generated a transmission i.e. AT+CMGS or the command which transmits a previously stored message at some loction <i>, AT+CMSS. The response from the AT+CMSS was +CMS ERROR: 321 which suggested I were trying to transmit an invalid memory index, which I knew to be false as I had successfully transmitted the message in this location using hyperterminal! Annoyingly, there was no error reported when using the AT+CMGS command, it just sat there and no SMS was received on my phone!

I bolied the problem down to something with my PIC hardware / software. Moreover it was something to do with the transmission commands, as every other command worked.

I noticed that when I tried to transmit an message the power LED on the board 'dipped' in brightness --- further investigation led me to spot that the modem needed 2A peak for transmission, however the power supply I were using only could deliver 1.1A. This seemed enough when ONLY the modem was being powered and the commands were coming from hyperterm, however when all my PIC circuit were sucking juice and trying to transmit then there was not enough power for everything!

I am sure you will agree this is a real suctle problem! I would have thought that there would have been some 'transmission error' messages which would be returned in situations like this - some feedback for the user!

What project are you working on? Are you using a GSM modem?

Regards

Tom

[frustrator]

Haha thats a good one. I actually thought of that today, the power drain would increase.

Your frustration came through in that first post. I sure would be.


Mate I am working on a GSM/GPRS terminal project. I wish to connect to a GPRS network, then access a mail server. Simple?

My problem is at the moment I can connect to my APN gateway, but hyperterm just sits there saying CONNECT. Great, I've connected to the GPRS APN, but can't get any further. I'm thinking I may have to write software to connect but surely you could do it all through hyperterm? I'm really unsure, it's all new to me.

I use the AT+CGDCONT to define my APN then dial *99***1# to connect. That's all I can find in the manual. Any ideas?

Chris

[tommyers]

Hi Chris,

I am not familar with GPRS, I have only used a GSM modem. The modem I have been using is the GM862-QUAD from roundsolutions. I speak very highly of roundsolutions (www.roundsolutions.com). They offer great quality products delivered to your door via UPS. They have a very repsonsive and upto date online from, discussing many aspects of their products, they have a great technical support team, should you ever need them - which will be unlikely as their documentation is written from an engineering perspective and soon gets you up and running.

May I ask whose modem you are using? Also, if you can provide me with some more details about your project - documentation, software etc.. I would be happy to take a look (I may fancy doing some GPRS work some day!). You may email me on: [email protected]

Cheers

Tom