[Help] Receive respone AT message from module SIM548C

[Delfy_Coltech]

Hi everybody!

I am doing a small project that uses dsPIC and module SIM548C.
I want to interface my PIC with that module.

I use UART1 (baud=19200) port of PIC to do that. You know that, when an AT command is sent to SIM module. It will respond with a string.

I want to receive all string responses from module SIM. How do I do this?

This is my code

[Ttelmah]

Several different possible things.

First, a 'string' in C, requires a null terminator. Without this, when you print your buffer, you will get loads of garbage displayed, as the print walks through memory, printing things, until it accidentally hits a '0'.
Normally strings from something like a modem, will have a line feed at the end of the line!. So check for this in your code, and if it is seen, add the terminating '0' to the buffer, and prematurely reset 'i'.
Also, remember the buffer should be _longer_ than the longest string you expect, by at least the character for the terminator...

Second, are you sure the module you are using is talking at 19200bps. Some require an initialisation to be sent when they first wake up (typically three line feeds), to set the baud rate to use. Unless this is happening, you module may be talking at the wrong rate. I think the default for the module you describe, is 115200bps, not 19200bps....

Third are you sure of your wiring?. You do realise that the module you have 'talks' RS232, _not_ TTL levels like the PIC, so a MAX232 or similar buffer is required between the PIC and this unit.

Best Wishes

[Delfy_Coltech]

Hi Mr. Ttelmah!
The third one, This modem can connect directly to microcontroller.
The second one, It also supports autobauding, so we don't need to setup baudrate for it. But I will try to setup a fix baudrate.
And the first one, I know that, I have written code to receive line feed and carriage return.

I think, 3 comments are very useful! I will review all

Thanks alot!
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Mechatronics Department, Coltech, VNUH
Hanoi, Vietnam.
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