gsm interfacing with arm7

hello
i am using sim300 and lpc2148 in my project. i am able to send the AT commands through uart1. bt unable to receive the response of module. it is showing a garbage on lcd 16x2

 RE: gsm interfacing with arm7

must be a bad lcd,,,, change it,,,,,,,,

 RE: gsm interfacing with arm7

1) How do you know that you are able to send AT commands through uart1? Maybe you are sending garbage to the module?

2) How do you know if the response from the module is real data, or garbage?

3) How do you know if your print code is able to print real data to the LCD?

For some reason, you give a minimalisting description that you have a problem. But no information at all about what you have done to try to figure out where the problem is. And since we haven't seen the code, we most definitely can't help spot any errors there either.

So what exactly was your goal with this thread? Just to inform us that there might be something wrong with SIM300 modules so we should avoid them? Or that ARM7-based processors are not compatible with SIM300? Or that SIM300 can't be used in projects with 16x2 LCD modules?

 RE: gsm interfacing with arm7

shashank,

first connect gsm module to pc and check it using UART. This will confirm that your model is working correctly or not.

Then instead of sending that data to LCD You can tap serial line between modem and lpc2148 board and see the response on PC hyperterminal.

Tap only transmit line of GSM module .... dont tap transmit line.

:)

 RE: gsm interfacing with arm7

"Tap only transmit line of GSM module .... dont tap transmit line."

Two serial ports on the PC allows both directions to be monitored.

 RE: gsm interfacing with arm7

oooppss I meant to say tap only transmit line of modem.... dont tap receive line..

I said this because when I did this, serial communication was not working.

 RE: gsm interfacing with arm7

Yes, trying to connect two transmitters to the same wire will not work well for RS-232 since the RS-232 transmitters don't have any enable support - they are not intended for bus designs.

But it really is very nice to connect the uc->modem line to the RX line of one PC serial port, and the modem->uc line to the RX line of another PC serial port. There are several programs available that can concurrently log data from multiple serial ports, and timestamp the data. That allows a developer to see the sequence of data sent to the modem, and data (echo and responses) sent back from the modem. Of course assuming that all connected parties have suitable baudrates, bit count, parity, etc.

I normally have a "pi" cable that connects unit A to unit B, while also sending RX and TX to two separate connectors for sniffing.