Sunday 16 August 2020

MEGA65 R3 PCB Testing

This week we have been testing all the changes made on the R3 PCB. The pain has been that we have a very tight time-frame for this, and I don't have one of the new R3 PCBs here with me.  

In short, we have to tell Trenz in the next day or so, whether there are any known problems with the board, so that they can order the bare PCBs in time for the DevKits to go out later in the year.  But COVID19 and logistics have thrown a spanner in the works, because I am here in the Australian Outback -- some 17,000km from the test boards in Germany -- and international freight is, shall we say, a little problematic at the moment.

So I am having to do the whole PCB bring-up stuff remotely.  Fortunately the R3 board is very similar to the R2 board, with just a few fix-ups in various places. The list of things that have changed in some way, includes:

1. Pull-ups included on all ports that were missing them on the R2.

2. POT line support on the joysticks, in a way that is compatible with the 1351 mouse and paddles.

3. SRQ line on the IEC port is now fully present.

4. Support for 2nd internal floppy drive on the 34-pin connector.

5. Internal speaker is now stereo, and using a different amplifier.

6. digital video / audio output now uses a direct FPGA connection instead of ADV7511 buffer chip.

(1) was easy to test: If the machine boots and works with joysticks and cartridges etc, without soldering anything on the board, then it is fine, which it is.

For (2), this was also fairly straight-forward, in that hooking up a mouse and testing it with a little BASIC programme is pretty simple.

(3) and (4) were also fairly straight-forward. The real problems with remotely testing are with (5) and (6), as I can't just poke and prod with my oscilloscope.  Even just checking if new registers are showing up becomes much harder.  We have had to coordinate across the oceans and time-zones, and do a lot of remote-desktop control, so that I can interact with the R3 PCB from afar:

To add to the fun, it looks like one of the three sample boards has a fault with the IEC port circuitry.

We have of course organised to send one of the boards here, but with COVID19, its really hard to predict when the board will make it here to Australia. Then when it does arrive in Australia, it has to get to where I live at the moment.  Normally I live in a large city, but not this year. This year for various reasons I am living in the middle of the Australian Outback. While this has a number of nice benefits, such as seeing pretty wild flowers, our fun lizards and other bush critters, and even a bit of opal hunting, as the following pictures show, it does also create some logistical problems...

Sturt's Desert Pea, the state's national flower, which is almost impossible to grow purposely, but sprouts up in the Outback, wherever it feels like.

Bearded Dragon warming itself on the road.

Edge-on view of opalised fossil cockle shell.

But back to those logistical problems...

I won't give my actual address here, but let's suffice by saying that it can be approximated as something like:

"The house the other side of the caravan park in the tiny village in the middle of the Outback, about 135 km from the nearest sealed road."

For the postal service, life is relatively simple: There is a private bag for the village (kind of a postal version of the old party-line phone lines), which gets picked up from the nearest regional centre (about a 6 hour drive away!), and then delivered to us on an Outback Mail Run twice a week.  While things might not be quite as tenacious as they were in the 1950s when Tom Kruse was the famous Outback Mailman, the posty still has to drive that 135km of rough, stony and corroguated dirt road.  

Where the post can go wrong, is if the post office in the city puts the post into the wrong private bag.  Then it goes to the wrong Outback Station, who hopefully realise and put it back into the next bag for collection by the posty.  That adds a week, then add another week for it to get back to us here. And that's assuming it doesn't sit on someone's mail shelf for a week or two, before they realise it isn't for one of their workers, and put it back in the bag, and then convince the post office to not put it straight back into their bag again the next week.  In short, the post can take upto 6 weeks to get here, if things go a bit pear shaped.  Even Tom Kruse was faster than that in his old Lleyland!

But for international couriers, its even more annoying: NO couriers deliver to Arkaroola, where we live. The tourist enterprise here has to ship their own supplies in, including all food, because they can't get any delivery service apart from the post. The nearest point that they will deliver is the end of the sealed road 135km away.

Fortunately we know folks who run the caravan park there, and they are kind enough to hold couriered parcels for us, and bring them over when they visit. So in theory we can get a parcel with the R3 PCB sent to them, and then get it over here quickly after that at the standard Outback surcharge of a cold beer. But first we have to get it to them...  And that's where COVID19 is playing jip with everything: International freight is quite impacted, so it might take a few weeks to get here. Or a few days. Noone can tell us, and DHLs tracking page is also not really telling us anything useful, only that the parcel has been cleared for departure from Frankfurt. 

And in the meantime, we continue to debug remotely...

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