Eric,
So i should put a 100 Ohm resistor in series on the tx line from the compass (rx pin on the mcu).
This from the 5V TX line from the Compass module to the Dev pcb
[5V source driving a 3.3V input [but 5V a tolerant input]
You say that shoud be ok for the receive, but the transmit...?
The TX from the Dev pcb source is at 3.3V to a 5V input on the Compass.
Its worth a try to see if the Compass will accept a 3.3V input
Also, driving the compass from the Z8 - do you meant supplying power to the compass module from one of the output pins of the Z8 (3.3v)? Would I also put a current limiting resistor there too?
No I would NOT suggest that, power the Compass from 5V in order to meet the spec.
What are your guesses with the serial protocol for that module - default 9600BAUD, 8 data bits, no parity, 1 stop bit, no flow control?
Looking at the Compass datasheet, I cant see the RS232 data update rate, so I guess its just continous.?
Initially use the defaults 9600, is fast enough for a Compass.
Sorry about all the (silly) questions