Hello,

I am using CY8Ckit-030 PSoC3 development kit..If i want to transmit AT commands to gsm modem then how UART of PSoC and UART of gsm modem should be connected ? And if i use UART_TX example project available in PSoC Creator then what should necessary changes should be done on UART and Character LCD components in Topdesign.cysch ? I have go through this topic http://www.cypress.com/?app=forum&id=2232&rID=52896  still there is no communication between the two.And how DCE to DCE communication done when there are female DB9 connector on both the sides?

The serial interface has never undergone a strong standardization as for instance USB or the Centronix interface. Thus a lot of experiencing (trial and error) has to be done.

First: a level-shifter is required to connect to another serial interface, MAX232 might be already on the board and should be enableg, consult the schematic.

The cable: To cross or not to cross, that's the question. Modems usually use hardware-handshake with RTS and CTS, TX and RX that has to be implemented in the PSoCs UART or (when possible) disabled in the modem.

Triple check the baud-rate!!! Check Start- and Stop-bits.

And: Make written notes, what you checked.

Bob

As Bob has mentioned, you have to do some experimenting. In my case, I had to cross the wire to make the comm work: TX on 1st connector is connected RX of 2nd connector, RX of 1st connector is connected TX of 2nd connector.

Hi vip11,

The project attached in the link you provided shows how a text message can be sent using SIM300 GSM modem to a number of your choice.

On The PC side DB9 connector, pin-2 isRx and pin-3 is Tx.

On the PSoC3 kit, Pin-2 is Tx and Pin-3 is Rx. In the GSM modem too Pin-2 is Tx and Pin-3 is Rx.

Hence, in order to establish comm b/w PSoC3 development kit and GSM modem, the pins 2 and 3 should be criss-crossed. Connect pin2 of kit to pin3 of GSM modem and vice versa.

Let us know if this works.

Thanks

bt  i have tried that gsm modem project .still it doesn't work..can you guide what other connections we can try to make it work?and how we can check whether UART is communicating or not? 

Use a scope and send "Hello world" over the UART.

Route the UART-Clock to an output pin and verify correct frequency

You'll always need a scope

You may connect the UART-TX to the UART-Rx and with a piece oft software you can see if the UART>> is able to talk to itself

Bob

Hi vip11,

As Bob has mentioned, you can test the UART by sending out sample strings like "Hello World".

One way to make sure that the UART in the project is sending out data from PSoC is to connect the UART terminals to PC's Hyperterminal. Use Hyperterminal to see if the commands such as "AT+CMGF=1" and "AT+CMGS="xxxxxxxxxx"" appears on the hyperterminal. Make sure that the baud rate set for both are same.

To be able to receive SMS via this modem make sure that the modem has acquired the channel. Waiting for a few seconds after the modem is powered on, or waiting till the Indicator LED blinks in a specific manner is another option to be sure that the channel is acquired.