I just spent a few minutes looking at the specifications for the devices, and found that these devices will
not work with each other on any Arduino form device when stacked.
I will summarize, and you can read the specifications to verify my analysis.
The X-Bee shield use COM1. (D0 and D1)
You can configure the GRPS device to use a hardware UART(COM1) or a software UART which uses
pins D7 and D8. Since COM1 is already in use, you would have to use a software UART and D7 and D8.
The Touch Shield uses the D7 and D8 as data pins. Conflict!
So, you are not able to stack the shields. You could use wire jumpers, and reassign the pins, which
would require changes to drivers, if they are available.
Where did I get the COM1 info? From you. “So, I found Xbee using COM1, and works excellent.”
It looks like the Gadgeteer connectors 1 and 2 are U types. That means they have UART support.
The schematic shows that they are connected to UART pins on the chip. In fact, connector 2
seems to have two UARTS.
The association of COM2 and COM3 to CPU pins is done within the firmware. I am not sure
which connector supports which COM port. With Gadgeteer, you do not need to know.
I would take a jumper and connect pin 4 to pin 5 (loopback) and write a small program which sends and receives.
Use this program to find with COM port is associated with which connector.
I was on the fence about modules for the longest, but I finally made the jump. I don’t know how many hours I have spent cutting trace wires, soldering and fixing shields to get these things to work together, and in the end it all looks like a christmas tree with hacked drivers and the occational cat chewing over something I didn’t notice.
“So, I found Xbee using COM1, and works excellent.”