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
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.
:)
"Tap only transmit line of GSM module .... dont tap transmit line."
Two serial ports on the PC allows both directions to be monitored.
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.
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.