starting with the basics, if you apply 3.3 volts between vcc and ground of the transmitter and 5v between vcc and ground on the reciever, how many volts do you measure between the ground and data pin in the reciever when the vcc and data pin are shorted together on the transmitter and also when the data pin on the transmitter is grounded? before asking about the beagle, let’s make sure the link hardware works. past this point I’d be inclined to use a serial port on each end rather than gpio.
Eric