AT commands via UART (RS232) from terminal to GR64


I need to send AT commands to a GR64. I’m using a MAX232 to convert RS232 to TTL levels for input to GR64.
I’ve wandered the forums to no avail.

I have 3 pins from RS232 (from PC) hooked up (DTM1, DFM1, and ground). I got the RS232 link (through the MAX232) to work with a microcontroller (that I will eventually attach to the GR64) so it seems to be on the GR64 side.

There is no response from the GR64 when I connect what I think is “correct”. If I fiddle around (remove common ground for example) I can get the GR64 to respond but it just echos the command. Other than that, I sometimes get gibberish returned, not sure under which conditions…

My GR64 dev-kit is on order (actually the carrier board alone is on order - apparently you order that separately).

Questions for you experts:
-Do I need to connect “Control signals (RTS1, CTS1)”. The docs don’t state this. They seem to be optional (?). (Section of the GR64 Integrators manual)
-Do I need to connect VREF? (I tried leaving it on VCC of GR64 board or on +V on MAX232 supply).

Can anyone suggest a better approach/product? I’ve ordered a Fastrack GO to try to just use a USB from a microcontroller (and supply the voltage).

Any advice is greatly appreciated.


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Apparently I just needed to look at UART1 diagram for Q64. … Rev003.pdf