I have a GSM862-GPS and breakout board and I am hoping to get it communicating over UART with a Freescale HCS12X microprocessor (this one specifically)
The GSM powers on fine, I have an LED hooked up to the PWR_CTL pin and when I power on it stays lit.
My level translation circuit is working fine. The Freescale uses 0-5v and the GSM uses 0-2.8v. I use a voltage divider (470/560) for Freescale TX and it should accept the 0-2.8v from the GSM on the RX. I have tested this by sending the command AT<carriage return> through the Freescale then through the divider and then looping it back to my Freescale's RX. The Freescale correctly reads the AT<carriage return>.
I have an oscilliscope hooked up and triggering from the GSMs RX line. (The manual mentions that RX and TX are named from a software standpoint, so RX on the GSM is its output). I turn the GSM module on, then when I press a button on my Freescale it sends AT<carriage return>, however I do not get a response from the GSM (confirmed on the oscilliscope). I would be expecting to recieve OK, but I get nothing.
I haven't seen many topics on getting stuck here, has anyone gotten past this point (GSM<>microprocessor over UART)? Does anyone have any ideas/suggestions as to the problem I'm having? I would love to get basic communication between the two devices working. I currently believe it could have to do with some of my UART settings on the Freescale. I'm currently using 38400 baud.
Thanks for your time,