Problem with GPRS shield (no communication at all)

jimbo.we · August 5, 2011, 3:31am

guan:

jimbo.we:

You can try to solder a wire to PIN1 of SIM900, and wire it to GND. In this way, you don’t need to pushing button all the time. By the way, when push the PWRKEY button PIN1 and PIN2 of SIM900 are connect together.

OK, as I said, I didn’t use the PWRKEY button, I used a jumper to connect pin 1 directly to GND.

I have now tried to run the updater in 19200 and 115200 bauds, and listened in. In 19200 baud, the firmware updater keeps sending decimal 255 and never receives a response. In 115200, the firmware updater keeps sending decimal 22, and never receives a respond. I’ve attached the logs.

By the way, this document suggests that there is a different debug port UART on the SIM900 and that this should be used for debugging and firmware updates. Are you sure the firmware updater will work with the regular UART?

About the UART， it is the right one。 I have confirm it with our supplier.