[aprssig] APRS-B? (FSK data?)

[Scott Miller]

> 1) sure, it needs SPI serial data handshaking and control to setup the
> chip and all the parameters, but I am still confused about the FSK/DATA
> pin.

I've run them in internal retimed mode, where the module handles syncing 
and clock recovery and you get bytes out of the FIFO over SPI in 
response to an interrupt.  Inputs and outputs are provided for direct 
FSK, where you skip those parts of the module.

> 2) After all the configuration is set by the external CPU or PIC chip and
> configured for FIFO OFF, then does this single  FSK/DATA pin act like a
> simple SERIAL DATA TX/RX line?  (meaning it could be directly connected to

It's an FSK input.  Driving it high sends the FM carrier one direction, 
driving it low sends it the other.

> I was assuming the external controls via SPI were only for set up and
> control, but that the FSK/DATA pin then became a transparent wireless link
> to the other end of the link?

Please, let's not plan on kludging these things together.  It's only a 
few bucks more to add an MCU on there to handle framing, error 
correction, and so forth.

I'll mail you some off-list.

Scott