Integrate Siemens TC35i Modem to micro controller

[zulkifli]

Hi All,

I have a query here regard to TC35i module.
I have a project to integrate between this module to uC. the problem is that, to talk to this module, it using AT command while, to write a code in uC using C or assembly. What i'm trying to do is to talk to each other using serial comm. which is available through pin out and in from the siemens module. refer to the block diagram attach, could anybody help me on how to integrate between this two?

**broken link removed**

Thanks

 

[dknguyen]

DId you try reading the Siemen's datasheets? I know it can be confusing but that's the only real way to go about it.

 

[zulkifli]

I did read all the datasheet from siemens. But, most of the time it mention using direct connection from module to computer and using hyperTerminal to send AT command.

 

[dknguyen]

WHat you are supposed to type into hyperterminal is exactly what the microcontroller is supposed to send over the UART. Hyperterminal is just a program to let a human send UART messages. A microcontroller does it directly by typing code that sends signals over the UART pins.

So if the datasheet tells you to type in "START" into hyperterminal, "START" is exactly what you program the microcontroller to send (in ASCII of course). ANd it says the modem will send back "MESSAGE 100" for you to read in hyperterminal, "MESSAGE 100" in ASCII is exactly what you get the microcontroller to search for.

SOmetimes if a device uses a UART but is not meant to be read in hyperterminal they may just have things in binary that makes no sense for a human to read. For example, sending the binary number 0xFF (or 0b11111111) might be the command for the modem to reset. THis is because it's faster to send just 1 byte to do something rater than to send 5 bytes for "RESET" (one byte per ASCII character). Since it's not meant to be displayed on a hypertemrinal screen in text form for a human, you can just send a different number for every command rather than a keyword in ACSII for that command.

 

[zulkifli]

Can i say and please confirm if i'm right before i start to work on this. So, for example, to talk to siemens module to know the version of the module by sending through hyperTerminal "AT^ver", so what i have to do to send the conversion type of "AT^ver" in ascii? if correct, thanks so much and i will try it at home and will get back to you if any problems if that ok. cheers

 

[dknguyen]

Yes, that is correct. You probably also have to enter an <enter> or <new line> or <clear line> or a combination of those characters in ASCII to tell you are finished sending the command (the modem will also end off it's responses like that). It should be somewhere in the datasheet.

 

[Silversolar]

Dear zulkifli,
I suggest that you get familiar with working with the TC35i modem connected to your PC serial port using the Hyper Terminal software with "AT" commands before you connect the TC35i to the uC. The Hyper Terminal configuration needs to be set with the correct port number (example Com1), Baudrate (example 9600 bits per second), Data bits (8), Parity (None), stop bit (1) and flow control (example none). If the setting is correct, type "AT" and Enter on the Hyper Terminal and the TC35i should response an "OK" on the screen.

Look into the rest of the ETSI AT commands of the TC35i to be familiar with how it works and try to duplicate the sequence of AT commands using the uC with the same baud rate you are using with the Hyper Terminal. Use a MAX232 chip between the uC and the TC35Ci serial port to translate the 0-5V of the uC to +12-12v signal required by the TC35i. Use PICBASIC or any convenient software to program the uC in sending AT commands. Correct signal frequency and polarity are key to successful connection.

Good luck.