1 wire network with an Atari 8-bit

Arcanis-Will · April 9, 2014

Looks good and you seem to be on the right path. You've already identified an non-obvious issue which is the fact that you can't just plug in the adapter since the Atari pinout is non-standard.

Also (if it was not already obvious to you), from looking at the schematic I see that the DB-9 adapter gets its power from the serial port on either RTS or DTR so your program will need to assert one of those control lines then wait a short time before attempting to talk to the adapter. I looked at the Atari schematic and it seems like you should use port 1. If you have a multimeter and you are using that DB-9 connector with the built-in screw terminals then you see either +10 or -8 volts on the control lines. it would be really easy to debug your initialization step and confirm that you have the +10 volts working on the right pin. If things don't seem to work you could go back and recheck that.

The 850 Operator's Manual has a lot of good information. I assume you will be using the Concurrent I/O mode? Seems like it is the only mode that fits the needs of realtime send & receive but it has the limitation that you can't do other peripheral access while it is active. So you should be sure to have a polling function that does not leave the Atari in concurrent mode permanently. My first attempt would be to write a polling subroutine that enables concurrent mode, gets an update, then disables it again before returning. This way it won't block you from saving your program to disk and/or loading data files, printing, etc.

Oh and the 850 that I have is also very brittle. The edge of the case had snapped off but luckily it was pushed inside so I still had it. I was able to superglue mine as well.

Good luck! Looks like fun!

Edited April 9, 2014 by Arcanis-Will

dneedham · April 9, 2014

Arcanis-Will Quote: "Also (if it was not already obvious to you), from looking at the schematic I see that the DB-9 adapter gets its power from the serial port on either RTS or DTR so your program will need to assert one of those control lines then wait a short time before attempting to talk to the adapter. I looked at the Atari schematic and it seems like you should use port 1. If you have a multimeter and you are using that DB-9 connector with the built-in screw terminals then you see either +10 or -8 volts on the control lines. it would be really easy to debug your initialization step and confirm that you have the +10 volts working on the right pin. If things don't seem to work you could go back and recheck that.

The 850 Operator's Manual has a lot of good information. I assume you will be using the Concurrent I/O mode? Seems like it is the only mode that fits the needs of realtime send & receive but it has the limitation that you can't do other peripheral access while it is active. So you should be sure to have a polling function that does not leave the Atari in concurrent mode permanently. My first attempt would be to write a polling subroutine that enables concurrent mode, gets an update, then disables it again before returning. This way it won't block you from saving your program to disk and/or loading data files, printing, etc."

Thanks for the great insight, I had looked at the 1-wire adapter schematic and was wondering about how it was getting power. Thanks for the advice, I agree that it looks like concurrent mode is what I have to use. I downloaded the 850 Operator's Manual and the 850 Technical Manual. I have the feeling I will be memorizing a lot of each manual Thanks again for the advice, I will post my findings, probably this weekend. Too much to do at work!

Edited April 9, 2014 by dneedham