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Re: a DIY home build project...

Posted: Sat Feb 10, 2018 8:22 pm
by tofro
Dave wrote:An exciting project.

The propeller won't need to do QLNET because that's fully implemented in the 8302.


"Fully implemented" is a nice expression for a single 1-bit port.

Tobias

Re: a DIY home build project...

Posted: Sat Feb 10, 2018 8:40 pm
by Dave
"At present, not all the possibilities implied by the above are implemented."
-- Tony Firshman, 1999

Re: a DIY home build project...

Posted: Sat Feb 10, 2018 10:20 pm
by Pr0f
I like that one...

As for the ZX8302 - I was going to make it history in the DIY design, so moving the QLNet function to the propeller makes sense as it avoids complications with speed sensitive code.

Serial data is done by the DUART, so I just need to put a 4 byte counter somewhere for the clock.

Re: a DIY home build project...

Posted: Sun Feb 11, 2018 12:53 am
by Dave
Since QLNET is just serial data at an odd speed, can you create a special mode/clocking for a simple UART so it can handle that functionality? That way it would have a common driver with the DUART. Code re-use is good.

Re: a DIY home build project...

Posted: Sun Feb 11, 2018 11:50 am
by martyn_hill
Hi Pr0f and Dave

Dave wrote:Since QLNET is just serial data at an odd speed, can you create a special mode/clocking for a simple UART so it can handle that functionality?


A couple of subtleties of the QLNet protocol down the wire that might complicate using an UART alone:
a) The 'SCOUT' phase is effectively run at a different bit-rate to the 11.2us bit-time of actual data - around 30-50uS per 'bit' (TK2 c30uS x 16, Minerva c50uS x 10).
b) How to implement the 'contention testing' during the SCOUT phase?
c) Need to leave the wire ACTIVE between bytes (4.5 to 5 bit-times) compared to the 1 to 2 stop-bits capability of a standard UART. (The ZXNet for example sends only 2-3 bit-times between bytes and this confuses the QL).

The Propeller on the other hand could take these in its stride...

Re: a DIY home build project...

Posted: Sun Feb 11, 2018 12:27 pm
by Pr0f
That's very good info - I am sure I came across and downloaded a protocol description for the QL net, time to go look for it...

Re: a DIY home build project...

Posted: Sun Feb 11, 2018 3:23 pm
by martyn_hill
Hi Pr0f

A good overview of QLNet is available as an appendix to the Tk2 documentation (see Dilwyn's site under Tk2), but it leaves-out a lot of low-level detail, that I have been able to augment through investigation for the QLUB Adapter project. I've posted some of my findings elsewhere in the forum and once completed, intend to document more fully.

Meanwhile, if you have any specific questions, let me know.

Re: a DIY home build project...

Posted: Wed Feb 14, 2018 2:19 pm
by Peter
tofro wrote:
Dave wrote:An exciting project.

The propeller won't need to do QLNET because that's fully implemented in the 8302.


"Fully implemented" is a nice expression for a single 1-bit port.

Tobias

On the QL, two 1-bit ports, one input and one output. ;) To do it with one tristate bidirectional port (and no transistor) is Q68 specific.