Posted: Sun Jul 10, 2011 8:36 am Post subject: Which GSM to send SMS? Newbie question...
I want to send a SMS with a ATMEGA8 or 324 microcontroller and a GSM. I have read a lot of this subject on this forum on how to do this and which GSM to use. I have tested this with a Nokia3310 and a Siemens M35 but with no luck.
I ran in serveral problems, PDU, FBUS etc. But I want to keep things simple...
What I want is a simple and cheap GSM to use so I can connect it with my ATMEGA and send in clear text SMS messages with AT Commands.
I have a few questions about this subject:
- Please advice which GSM to buy to accomplish this? (no more than ±20 euro´s on ebay)
- Do I need to use an external oscillator or can I use the internal oscillator of the ATMEGA to send the AT commands to the GSM?
- Which pins do I need to use to connect the GSM to the ATMEGA? Now I only use one pin: from GSM Rx to ATMEGA Tx. Is that correct or do I need to connect more pins?
Posted: Sun Jul 10, 2011 9:51 pm Post subject: Re: Which GSM to send SMS? Newbie question...
rbruinsma wrote:
I want to send a SMS with a ATMEGA8 or 324 microcontroller and a GSM. I have read a lot of this subject on this forum on how to do this and which GSM to use. I have tested this with a Nokia3310 and a Siemens M35 but with no luck.
I ran in serveral problems, PDU, FBUS etc. But I want to keep things simple...
What I want is a simple and cheap GSM to use so I can connect it with my ATMEGA and send in clear text SMS messages with AT Commands.
I have a few questions about this subject:
- Please advice which GSM to buy to accomplish this? (no more than ±20 euro´s on ebay)
- Do I need to use an external oscillator or can I use the internal oscillator of the ATMEGA to send the AT commands to the GSM?
- Which pins do I need to use to connect the GSM to the ATMEGA? Now I only use one pin: from GSM Rx to ATMEGA Tx. Is that correct or do I need to connect more pins?
All help and answers are welcome, thanks!
- use a m324P or any other micro that has 2 UARTS. you need one uart for the gsm, the orther for debug
- you can best use a gsm modem like SIMCON 300 (has a connected which is easy to solder) or a SIMCON 900 (newer but SMD). you could also use a BT module if you use a mobi with BT module. Or use an old mobi which can be controlled by RS-232. All depends if you need just one, or more.
- for low baud rate you can use th einternal osc, but i would recommend using a crystal.
- you need to connect TX of mega to the RX of the modem. you must take care of the voltage. Most modems accept not more then 2.8V
- connect RX of mega to TX of the modem.
if using a phone with interface, maybe all you need is a max232 level converter. it all depends on the phone then.
- first send some AT commands :
print "AT"
and see if you get an OK back.
check out the recon project from the AN. _________________ Mark
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