FS: USB "POST box" adaptors (for debugging Archimedes / Risc PC systems that don't boot)

[myelin]

As seen in the Acorn "POST box" display adaptor (0086,804) thread, I have designed a PCB with an FPGA running Phil Pemberton's POST interface, plus a USB microcontroller that provides a communication channel to let you fully interface with the self-test code present in RISC OS 2.01 - 3.70. This lets you do the following in a machine that doesn't make it all the way through the boot process:

- see the detailed self-test output (over a USB serial port, for easy copying and pasting)
- read and write memory, run bus cycles, and execute code (from a Python script running on the host machine)

I plan to make more of these, because they're so very useful. Thanks to this project, I managed to repair the most corroded A5000 I've ever seen, which I was starting to think would never be possible.

I'm just making them at cost, so they're US$20 plus US$11 for shipping to the UK, which works out to around £25 all up.

You'll get a board like one of the ones pictured above, and will need to add a micro USB cable (for connection to your laptop) and six female-to-female "DuPont" wires (for connection to the target machine).

If interested, please post here, and I'll add you to the queue at the end of this post, and PM you asking for payment and a shipping address when I have a board ready for you. Please be patient, as they're being assembled by hand and my production capacity here is about three a week The plan is to just keep ordering components and PCBs when they run out, and make and post a few at a time, so there aren't any "batches" as such, just a backlog that I'll hopefully eventually get through!

And of course this is open source, so you're welcome to make your own if you like: PCB, HDL + firmware

In use
- Board #1: r1, myelin
- Board #2: r1, philpem
- Board #3: r1, steve3000
- Board #4: r1, anightin
- Board #5: r2, myelin
- Board #6: r2, IanJeffray

Sent
- Board #7: r2, danielj
- Board #8: r2, dangardner
- Board #9: r2, RobC

Ready to post out

Building/testing

Queue
- herrwieger
- spanners
- sbadger
- BeebMaster
- KarateEd
- IanS
- stevebubs
- Xavier x 2
- Corum
- 1024MAK
- VectorEyes
- Paul
- DutchAcorn
- 8271
- CJS
- Boydie
- lcww1
- Stevetuc
- steven_gilson

[herrwieger]

Hi!

Sounds awesome. I take one if shipping to Germany is possible.

Great work!

best regards,

Thomas

[anightin]

Yes please!

Best

Andy

[dangardner]

One for me too please!

[steve3000]

ohhh, yes, one for me please

[RobC]

I'd love one too please! It might let me finally sort out my A5000s...

[spanners]

Yes! Put me down for one.

D.

[danielj]

Me too

d.

[sbadger]

Yes please (to UK)

[myelin]

Great! Looks like there's enough interest to use up all the PCBs I have here, and if this continues, do a second run.

philpem sent some notes from his initial tests and there's a couple of things I'd like to get more info on, so the two boards I have right now will go to anightin and steve3000 for more testing, and I'll go order some more components so I can make some for everyone else!

[BeebMaster]

I'd like one please, if it's not too late.

[myelin]

Sounds awesome. I take one if shipping to Germany is possible.

Shipping to Germany is no problem You're first on the list after the two priority testers.

I'd like one please, if it's not too late.

Not too late at all! I plan to do this as a continuous thing, making a few boards at a time and slowly working through the queue. It'll take a while (a few weeks maybe?) but unless I decide to stop making these, they'll always be available.

I realized that not actually offering built versions of my designs was causing lots of useful things to be forgotten, so I'm planning on doing the same thing with some of my other designs, like the Electron FX2/Tube/PiTubeDirect interface, the Econet hub, and maybe some other bits and pieces. It looks like building POST box boards will keep me busy for the next little while though

[steve3000]

Great! Looks like there's enough interest to use up all the PCBs I have here, and if this continues, do a second run.

philpem sent some notes from his initial tests and there's a couple of things I'd like to get more info on, so the two boards I have right now will go to anightin and steve3000 for more testing, and I'll go order some more components so I can make some for everyone else!

Brilliant, I’ll dig out my dead A5000 this weekend!

[KarateEd]

Hi Myelin,

I would love to have one of those. I see you probably would have to do another run but count me in if you do so.

Thanks,

[myelin]

I would love to have one of those. I see you probably would have to do another run but count me in if you do so.

That's the plan! I'll update here as components arrive and boards get built

[IanS]

Looks like a useful addition to the toolkit. Please add me to the list. Thanks.

[myelin]

Looks like a useful addition to the toolkit. Please add me to the list. Thanks.

Added!

[danielj]

Thanks Phil - impressive work on these and impressive results on the A5000

d.

[stevebubs]

Please could you add me to the list. Have a few machines that could do with a bit of TLC.

[myelin]

Please could you add me to the list. Have a few machines that could do with a bit of TLC.

Added!

[myelin]

anightin and steve3000, your boards are in the mail!

Some early test data is back from philpem, who has been using his board... so one big thing is to be extra careful about the cable wiring, as this has no reverse polarity protection (or, well, the static protection diodes in the 74HCT125 and 74LCX125 end up becoming clamping diodes; the 74LCX125 on philpem's board now heats up every time he uses it...). Apparently his A4000 has the silkscreen the wrong way around for the POST connector, so you'll want to use a multimeter to double check that pin 1 is connected to 5V and not ground before powering up the target system.

I spent quite a long time getting this design to handle the two independent power supplies properly, so that you could switch the target on and off and plug/unplug the USB cable whenever you like without either side parasitically powering the other, but completely forgot about handling cable faults. I'm going to revise the design to make it more tolerant of cable faults (more resistors, some polyfuses and diodes, and an isolator chip) before making any more, unless anyone would prefer to get a rev 1 board sooner rather than wait for the tougher rev 2.

^^^ If you *would* rather get a rev 1 board straight away rather than wait an extra month or so, just post here, and I'll add a note next to your name in the queue!

[BeebMaster]

Think I'd better wait for Rev 2, since I'm still reeling from blowing up an external HDD's SATA controller the other week by feeding it incorrect polarity...

Where's the Third Doctor when you need him!

[danielj]

^^^ If you *would* rather get a rev 1 board straight away rather than wait an extra month or so, just post here, and I'll add a note next to your name in the queue!

I'm quite happy to have a non-fire-proof product I won't hold you responsible for any explosions!


d.

[anightin]

anightin and steve3000, your boards are in the mail!

Some early test data is back from philpem, who has been using his board... so one big thing is to be extra careful about the cable wiring, as this has no reverse polarity protection (or, well, the static protection diodes in the 74HCT125 and 74LCX125 end up becoming clamping diodes; the 74LCX125 on philpem's board now heats up every time he uses it...). Apparently his A4000 has the silkscreen the wrong way around for the POST connector, so you'll want to use a multimeter to double check that pin 1 is connected to 5V and not ground before powering up the target system.

I spent quite a long time getting this design to handle the two independent power supplies properly, so that you could switch the target on and off and plug/unplug the USB cable whenever you like without either side parasitically powering the other, but completely forgot about handling cable faults. I'm going to revise the design to make it more tolerant of cable faults (more resistors, some polyfuses and diodes, and an isolator chip) before making any more, unless anyone would prefer to get a rev 1 board sooner rather than wait for the tougher rev 2.

^^^ If you *would* rather get a rev 1 board straight away rather than wait an extra month or so, just post here, and I'll add a note next to your name in the queue!

Well noted and thanks Myelin!

[steve3000]

anightin and steve3000, your boards are in the mail!

Looking forward to recieving it! And thanks for the advice to check connector polarity. I do have one partly dead A5000 where the electrolytic capacitors are all fitted backwards, but I think the silkscreen was ok...

[Corum]

I also would like to buy an adapter.
Shipping to Germany

best regards
Corum

[KarateEd]

As much as I hate to wait, I suppose I should wait for revision 2 because my tendency is to get things reversed at times. That also seems, for some reason, to cause extra projects.

[1024MAK]

Hi myelin

Can you please add me to the list for one “POST” adaptor.

Mark

[philpem]

Some early test data is back from philpem, who has been using his board... so one big thing is to be extra careful about the cable wiring, as this has no reverse polarity protection (or, well, the static protection diodes in the 74HCT125 and 74LCX125 end up becoming clamping diodes; the 74LCX125 on philpem's board now heats up every time he uses it...). Apparently his A4000 has the silkscreen the wrong way around for the POST connector, so you'll want to use a multimeter to double check that pin 1 is connected to 5V and not ground before powering up the target system.

Turns out my A4000 has the silkscreen the right way round. My cable flipped the pins 1->6, 2->5, etc. I've changed the cable out for a 1->1 wired one with colour coding...

[VectorEyes]

Given that I have about 5 RiscPCs and a variety of other machines that could do with some fixing ... at some point in the future ... please could I be added to the queue?

Thanks!