Hi all

I have a cellular modem that supports text and pdu format SMS messages, I have read on the internet that the PDU format is more commonly implemented and I have gone down this track and have a working send and receive system with all the appropriate error checking etc on my NXP P89LPC925. while this is all well and good, I have under estimated the amount of RAM that the whole process takes. (121bytes in Data and 110bytes in Xdata) this includes a 50Byte message buffer, and a 100Byte UART buffer

Now I have the issue where I can't do anything useful with the SMS, as it uses all the RAM to buffer and parse the messages (and even then only very short ones).

Would I be better off going to text mode on the modem? I personally can't see how, as I still need to read all the messages in first. but I maybe able to process the text on the fly rather than having to buffer it and then decode it.

Any ideas?

I need to implement I2C on the micro as well, and this also requires a little bit of RAM.

I found a good application note. "AVR323: Interfacing GSM modems" on the atmel website. www.atmel.com/dyn/resources/prod_documents/doc8016.pdf

I modified the code slightly to use unsigned chars, and also a full state machine for the modem responses, as this gets rid of while(I wait for a timeout) loop in the code, and allows my watchdog to keep operating.

Regards

Marshall