Interface spec for PPT interface? - Need specs - can't find them!

[mantonj]

I am trying to get one of the many Tx->Parallel port interface circuits working. It is complicated by the fact that I have a JR Quattro receiver (four channel), that puts out a 1V peak-to-peak signal, which is lower than other radios, and even (it seems) than other JR's.

I know something about electronics (I am a PhD student in Electrical Engineering). I have a reasonable lab at home, but nice instruments don't help if I don't know what the electrical and logical protocol is for the parallel port interface for FMS.

I've looked through the docs on the FMS website, and all I find are example circuits (which are apparently of varying quality). I've visited users' websites, but the only really good info I got was for the serial port interface.

Can anyone give a straightforward description of the parallel port FMS interface, including parallel port pin numbers, electrical signal strengths (voltage and current, if appropriate - though I can get that from the IEEE 1284 standard), control signal formats, and, if necessary logical signal format (it looks like it just takes the pulsed signal coming out of the buddy port, so logical format is probably un-necessary).

OS - Win98 SR2

If I can get some good info, I promise to compile it into something that is accessible to the layman, to benefit the community as a whole.

Jonathan

[Steve Lewin]

I think you may be overcomplicating this. The signal format is the standard transmitter encoder output format. It is used to toggle nAck (Pin 10) at the usual TTL levels. Ground is on any of pins 18 to 25. No other pins are used and all control, timing etc are in software. It doesn't matter if you invert the signal or not. It wags nAck up and down. That's all.

Just use one of the many circuits containing a transistor and it should work.

Steve