Is there any application note on interfacing GSM modem with PSoC 3. primarly i want to interface the GSM modem with PSoC 3 and communicate with Hyperteminal by sending and recieving simple text messages.

We do not have any project or App Note for GSM modem. However, it is easy interface any GSM modem with PSoC via UART. Any GSM modem can accept commands from PSoC. These commands are called AT commands. Different AT commands sent from PSoC to GSM modem is interpreted differently and the modem performs suitable operation. Hence, a possible implementation to interface GSM modem with PSoC is to connect, the GSM modem to RX and TX lines of PSoC and send AT commands. Each GSM modem datasheet provides a set of AT Commands that the modem can accept. Go through this datasheet and send these commands from PSoC. 

Hi Cbraj,

You can download a sample project on UART and modify it to send AT commands to send and receive text messages from GSM Modem.

You can connect the GSM modem to a PC to send and receive text messages via Hyperterminal. In this case UART is used for communication between the GSM modem and PC.

When you are interfacing the GSM Modem with PSoC, you are replacing the PC with PSoC so that the UART is used to send AT commands to GSM modem by PSoC.

Hi Cbraj,

If we take an example of GSM modem SIM300, then the AT commands which have to be used to send text message would be something like this:

AT+CMGF=1 0x0D

AT+CMGS="xxxxxxxxxx" 0x0D

"Message to be sent" 0x1A

Here 0x0D is the Carriage Return (Equivalent of this in PC is the 'Enter' key).

The equivalent of 0x1A in PC is 'Control + Z'.

xxxxxxxxxx refers to the phone number to which the text message is to be sent.

These commands have to be sent via UART.

A project is attached which demonstrates the sending of these commands. You can modify it according to your requirement.