GSM Module

How do I connect this module to Arduino UNO?
http://www.futurashop.it/allegato/8100-TDGGSM_900.asp?L2=CORRELATI&L1=8100-TDG134&L3=&cd=8100-TDGGSM_900&nVt=&d=60,00

Datasheet:
http://www.futuraelettronica.net/pdf_ita/8100-TDGGSM_900.pdf

Or this one?
http://www.futurashop.it/allegato/8170-SIM900.asp?L2=MODULI%20GSM&L1=MODULI%20GSM%20E%20SISTEMI%20GPS&L3=&cd=8170-SIM900&nVt=&d=48,00#sopra

There appear to quite a few serial handshaking signals that you may not need so I reckon the following...

RESET -> any spare digital pin, use to reset the board
ON/OFF -> any spare digital pin, use to power up/down the board
VCC/GND -> same on Arduino
RX -> any spare digital pin, use as your serial output (probably, depends on their naming convention)
TX -> any spare digital pin, use as your serial input (probably, depends on their naming convention)
CTS/DCD/RTS/DTR ? some may need to be tied to enable an internal UART
RI -> may be usable as an interrupt

It looks fairly straight forward but you really need a proper data sheet, even if you get the pins right what are you going to say to the thing?


Rob

You can see the datasheets by clicking on PDF icon in the page.
First datasheet is quite useless, but second one says:
"Control via AT commands GSM 07.07, 07.05"

But isn't enough to just connect RX, TX to arduino to control a serial-controlled device?

First datasheet is quite useless, but second one says:

OK I found the second one and it's little better than the first. I haven't used AT commands for 20 years so unless someone else here is up to speed on them you'd better start Googling, better still ask the guys selling this to point you in the right direction.

On one sheet the chip is referred to as a GSM1, whereas the other sheet is about an SIM900, are they the same chip? The SIM900 talks about SPI, I2C etc but these atren't on the schematic. The SIM900 does however have a stack of UART_xxx pins which presumably are the handshaking lines on the first sheet.

Looking at a few of the pins they do appear to be the same.

But isn't enough to just connect RX, TX to arduino to control a serial-controlled device?

CTS/DCD/RTS/DTR etc are handshaking signals, presumably they are used or they wouldn't be there. If they are used then some of them will need to be tied low (or maybe high).

But apart from that you're right, you should just need Tx and Rx. BUT, what are you going to say and what do you expect from the device.

You need to know

a) What are the AT commands it needs, and
b) What (if any) handshaking lines need to be dealt with.

With a chip of this complexity there should be a programmer's manual of some kind. Get onto sim.com (I tried but the site was down) and see if they have a real data sheet.


Rob