Receive SMS with Picdem.net 2 and a gsmModem via RS232

jojo337 · Joined: 05 Apr 2013 Posts: 8

Hello all ! (Sorry for my mistakes, I'm french)

I actually have a Development card Picdem.net2 with a Pic18f97j60. And my program for compilation is PCW, CCS C compiler.

I'm a beginner in coding.

So I got a Telit gt864-quad modem GSM who works fine. I know a bit the AT commands. I can send sms with PIC, this is working. But I don't know how to got the answer of the command, my code doesn't work for this, so I think I can't read SMSs too.

I use printf("...") to send commands.
I use printf(lcd_putc, "...") to show things on the LCD.

For example, when I send the command AT+CPIN=0000, there is an echo, and it says OK with \r\n at the end (0d 0a in hexa) when I try it with Hyperterminal.
But with my code, i obtain "AT" on the lcd, and the code stop, don't continue.

I'm not good at coding, can you help me ? Here is the code of my program :

Here, I tried to put on the LCD the result of sending the first command.

Ttelmah · Joined: 11 Mar 2010 Posts: 19498

Some comments first:

setup_adc(ADC_CLOCK_DIV_2|ADC_TAD_MUL_0);

Hopefully you are not using the ADC. If so, either don't call setup_adc, or use:

setup_adc(ADC_OFF);

The maximum CPU clock speed supported by your setting is 2.86MHz.....

setup_spi(SPI_SS_DISABLED);
setup_spi2(SPI_SS_DISABLED);

Wrong.

setup_spi(FALSE);
setup_spi2(FALSE);

you are enabling the spi, and saying not to use slave select.....

Then the key thing is to remember that your code needs to be receiving data from the serial whenever it arrives. You can't sit in a delay, then go and see if anything has come, since it will have been lost (except for a couple of characters in the hardware buffer). You need to be using code like EX_SISR.C. to receive everything that arrives from the modem, then parse it from the buffer.

Now you don't show your RS232 setup, this _must_ have the keyword ERRORS in it. This _must_ always be present when using the hardware serial, unless your own code, handles errors. Without this, and without an interrupt driven serial receive, two characters will be received, then the UART hardware buffer will overflow. The response to this is to switch off the UART, till the error is cleared. These two characters are the 'AT' you get. Everything after this has been lost.

So:
Add errors.
Use code like EX_SISR, setup a buffer with this perhaps 64 characters long, and then read the data from this.

Best Wishes

jojo337 · Joined: 05 Apr 2013 Posts: 8

Thanks for your answer !

So for all the setup_*** lines, it was already on the code at start. I used "PIC Wizard", where we can configure a bit the code.

Here is the main.h :

ezflyr · Joined: 25 Oct 2010 Posts: 1019 Location: Tewksbury, MA

Hi,

Do this:

jojo337 · Joined: 05 Apr 2013 Posts: 8

The compilator says that there is a warning, that rs232_errors is never used when I compile.

Thanks.

temtronic · Posted: Fri Apr 05, 2013 7:04 am

hay John..yup...'defaults'..are based on the programmer's 'typical' use.
Maybe 'way back then' when the compiler was created, programmers took care of 'details' like error checking themselves...
The really bad 'default' is MCHP having I/O pins defaulting to analog and not digital use.
Might be why we're supposeed to read the datasheets and manuals !

cheers
jay

ezflyr · Joined: 25 Oct 2010 Posts: 1019 Location: Tewksbury, MA

Hi,

That's "normal", you can just ignore the warning.

Just as a friendly suggestion, all of this (GSM projects, UART data reception, 'Errors', etc., etc.) have been covered extensively in the forum. Your standard method for solving a problem should be something like this:

1. Search CCS documentation
2. Search CCS forum
3. Search Internet (Google, etc.)
4. Ask question on forum!

The question you just asked has been asked/answered 100's of times here on the forum!

John

jojo337 · Joined: 05 Apr 2013 Posts: 8

I understand. I am searching since some days now, but it wasn't the "same type of coding" (this wasn't CCS I think).

So now I can see all the text in the LCD when I added "Errors" thanks !

But if launch a second time the program, the message is not the same. It is cutted. Because the char test[50] is not resetted ?

Thanks again.

ezflyr · Joined: 25 Oct 2010 Posts: 1019 Location: Tewksbury, MA

Hi,

Who knows? It really depends on what you mean by "launch a second time the program". A more important point is that the hardware is right there in front of you, it's not in front of us. That means you should be trying to troubleshoot and solve the problem yourself, rather than running to the forum to ask a question every time you encounter something unexpected!

You've taken your GSM project a lot further than most here on the forum, so I highly encourage you to keep experimenting and keep learning, and only ask questions here when you absolutely cannot find the answer any other way!

John

jojo337 · Joined: 05 Apr 2013 Posts: 8

Ok, I will do this. Thanks.

ezflyr · Joined: 25 Oct 2010 Posts: 1019 Location: Tewksbury, MA

Hi again,

Another thought! LCD's actually make a fairly poor tool for diagnostics during software development. I prefer to dedicate a pin on my PIC to use for sending serial diagnostic messages to my PC. Connect the pin you use to the serial port of your PC via a MAX232 device. All my boards include a 4 pin header for serial diagnostics (Vcc, TxD, RxD, and Gnd). I have a small interface board that I plug into the header during program development. If you plan to do any embedded development at all, it's worth your while to do something similar! You can setup a 2nd serial port on your PIC, and use 'Streams' to direct serial data appropriately!

John

jojo337 · Joined: 05 Apr 2013 Posts: 8

Hi. We don't have a MAX232 device in my school, and the project will be finished in 1 week Sad

Last question : Is it possible to check a received message if it contains a word in the PIC ? I Try to do 'if test != "ERROR"' but didn't worked, the program stops.
I think that it is because it search only if the message is "ERROR", and not if the message contains "ERROR". But I don't find any thing about this in internet. Hae you an Idea ?

Thanks.

Ttelmah · Joined: 11 Mar 2010 Posts: 19498

This is basic C.
In C, a string is not a 'type', but an array of characters. Since it is an array, you can't compare it like a number. Look at strcmp, and get yourself a C textbook.

ezflyr · Joined: 25 Oct 2010 Posts: 1019 Location: Tewksbury, MA

Hi,

I've been trying to gently "encourage" you to spend more time researching your questions, and solving problems on your own. If you can't do this, you aren't going to ever be worth much a an "engineer"......

There is a complete program posted in the forum that receives TXT messages, and then sets relays in response. This program was written by forum user 'Gabriel', and can be found in the Code Library. Since you haven't figured out how to search the forums yet, here is the link: http://www.ccsinfo.com/forum/viewtopic.php?t=42527

If I sound frustrated, that's because I am. There is a complete program already available to do what you want, but you could not be bothered to do any research and find it! This is becoming an epidemic lately on the forum with lots of people just wanting "solutions", but not really focused on learning anything.....

John

jojo337 · Joined: 05 Apr 2013 Posts: 8

Hi.

I apologize to have bothered you. I don't want the solution and just copy/paste it. I already saw Gabriel's code but because I just started programming, I don't understand some parts of his code, even if there are comments. I try to adapt it to my code, because this was not exactly the same type of coding, not the same writing.

I will watch again this week this code with my friend. Thanks.