SIM900R with 16F877A Communication Problem

[ezflyr]

Hi,

Are you trying to receive/parse the SMS text message that follows in response to the 'CMGR' command? If so, you should just tell us that!

Cheers,

John

[umutso]

Hi

I got it working now. And no not want to parse SMS that I m dealing with 2 way communication via tcp stack. Data goes ok and want to parse the data back which is working.

Now I need one thing more. I want to store some int values in the internal EEPROM of 877a. I can write to address without error. For eg 66 decimal. When I want to read it I always receive garbage from the address with read_eeprom(1) simply. And I write with write_eeprom(1,intvalue).

What do you think the problem can be?

Thanks
_________________
Umut Sonkurt

[ezflyr]

Hi,

Are you writing an int8 value to the EEPROM? Your code should work as written. Have you tried other EEPROM memory locations to see if they have the same problem? An EEPROM memory cell has a finite write cycle life, and if you exceed that life (such as by putting the Write inside a loop), it's possible to kill an individual memory location.

If other memory cells have the same problem, write a small test program that writes to EEPROM, and then immediately reads the value right back with nothing else in the program. Does that work? If not, post this test program!

John

[SSR]

The OP.

Have you used any converter between the GPRS and Controller? Because i have read that SIM900 runs on 3V.

[ezflyr]

Hi,

Frankly, the SIM900 datasheet is a much better resource for this information than the CCS forum!

The SIM900 can be powered from 3.0V to 4.2V. If you want to make your life easier, just power your PIC and your GSM module at the same voltage, and you will eliminate the need for 'level converters' between the PIC and the GSM module....

John

[SSR]

Thanks John. I was missing this.