BBC Model B implementatation for myStorm BlackIce

Speculatrix 2017-09-23 19:05:34 UTC #41

Hi Guys - Got my BlackIce today, as well as Digilent PModVGA and PModPS2 adapters. I got the icebootbeeb.raw file downloaded onto the device okay (at least, it said 'File downloaded successfully'). When I power up the BlackIce I get the white PWR LED and a single red LED. But none of the three monitors I tried claims to be seeing any signal from the VGA. What's the first thing I should check?

hoglet 2017-09-23 19:46:43 UTC #42

Here's a couple of simple tests:

Pressing caps lock on the PS/2 keyboard should toggle the red LED.

Pressing print-scrn on the PS/2 keyboard should light the green LED (while pressed)

If this works, the FPGA bitstrream and ROMs have downloaded and the problem is just the video.

If that's the case, possibly it's just the 50Hz refresh rate that's not supported by any of your monitors.

You could try the Acorn Atom design which has a 60Hz refresh rate. The would confirm your PMod VGA is working correctly.

Dave

Speculatrix 2017-09-23 20:04:23 UTC #43

Thanks Dave - I'll give all that a go tomorrow...

Speculatrix 2017-09-23 20:19:15 UTC #44

Hmm... I actually did a quick check with the keyboard - no dice. Just the one red LED glowing relentlessly.

BTW, the output from dfu-util when downloading was:

dfu-util 0.8

dfu-util: Invalid DFU suffix signature
dfu-util: A valid DFU suffix will be required in a future dfu-util release!!!
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuERROR, status = 10
dfuERROR, clearing status
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
DfuSe interface name: "Internal Flash "
Downloading to address = 0x08000000, size = 262080
Download [=========================] 100% 262080 bytes
Download done.
File downloaded successfully

I'll try another keyboard tomorrow, too.

hoglet 2017-09-23 20:35:50 UTC #45

That log looks fine to me.

I'm suspecting you have both a keyboard and a monitor issue.

Can you try the Acorn Atom design; that will give us another data point:
https://github.com/hoglet67/Ice40Atom/raw/master/releases/ice40atom_20170911_1205.zip

The frame rate here is always 60Hz, so it should work on all VGA monitors.

This would then let you see if your keyboard is happy running off 3.3V.

Dave

piers 2017-09-24 06:36:50 UTC #46

Could a future hardware revision of the blackice add the ability to select the pmod voltage (5v or 3.3v) as the spec allows?
This could be for a subset of the pmod interfaces, to allow more keyboards to work with the blackice board (e.g. just the single pmod interfaces).
The pmod interface board would (probably) have to have level shifters on it for the data and clock lines - which I presume the digilent one doesn't have.

piers 2017-09-24 06:48:01 UTC #47

PS2 keyboards are (obviously) much easier to interface to an FPGA than USB keyboards, but are becoming rather rare.
Some of the early USB keyboards came with a USB to PS2 adapter, but I think this required the keyboard detect the interface the PC was using on power-up so it could switch to PS2 mode.
Could the STM32 be used to convert USB to PS2 / serial messages or can it only act as a USB device?

hoglet 2017-09-24 06:59:22 UTC #48

It seems to be device only (i.e. cannot function as a USB master).

Digilent handle this on their PS/2 PMOD by allowing 5V to be supplied externally via a jumper:

5V is available on BlackIce from pins 2 and 4 of the 26-pin comms header, and also pin 12 of the digital3 header.

Dave

Speculatrix 2017-09-24 08:16:24 UTC #49

Okay, so I tried the Atom - with the same results. Tried two different displays (an older 4:3 LCD panel and a TV with RGB input) still with nothing. As for the keyboard, I tried again with my PS/2 keyboard (brief flash of its LEDs when first powered up, but nothing after that) and a cheap USB board with an adapter. Also no joy.

I have to go do boring things now, but will investigate further tonight or tomorrow.

hoglet 2017-09-24 08:58:19 UTC #50

Same LEDs?

I would stick with the Atom for a bit, because:
- it will generate a VGA output even in no code is executing on the 6502 (the Beeb needs the MOS to correctly configure the 6845 before a valid video signal is generated)
- the VGA is at 60Hz so should work with all monitors

Check you have correctly replaced the DFU mode jumper between pins 14 and 16,

Connect a USB cable to the edge USB connector, and run a terminal at 115,200 baud. Hit the reset switch. You should see some output on the terminal. Can you paste that in here.

Can you also post a photo of your setup?

Dave

Speculatrix 2017-09-24 09:07:03 UTC #51

It was the jumper. I don't think it was making proper contact. I've replaced it with a short jumper cable (so much easier to manage) and the Atom is now working. Yay! Now I really should get back to my lunch guests - but thanks for your help & patience.

piers 2017-09-24 10:53:05 UTC #52

Thanks Dave,
Wouldn't a 5v keyboard use 5v signal levels? That should be fine for the clock and data going to the keyboard (it should see 3.3v as logic 1), but the keyboard to FPGA signal will be at 5v.
The 200 ohm resistor should protect the FPGA, unless the keyboard's data signal sources more than 8.5mA
So the only benefit of adding a voltage selector to the blackice would be convenience.

Shame the STM32 can't be a USB master as USB keyboard to PS2 converters don't tend to work with cheap USB keyboards, and PS2 keyboards tend not to be cheap.
These are not big hurdles for individual projects, but could hinder greater adoption (not sure where Alan & Ken want myStorm to go to, but as it provides a low-cost open programmable hardware platform I can see it being useful in education)

Hopefully Speculatrix has found the fix and getting keyboards to work with the myStorm won't be too hard!

hoglet 2017-09-24 12:42:01 UTC #53

PS/2 keyboards are meant to use open collector outputs, so the only thing pulling the signals high should be the pullups. Most FPGA PS/2 interface designs I have seen also use 390R series resistors to be safe. I think the iCE40 has clamping diodes, but the data sheet isn't 100% clear on this.

Speculatrix 2017-09-24 13:40:12 UTC #54

Yep, mostly got it solved. I reflashed with the Beeb. Keyboard (the USB one via PS/2 adapter) works fine. On two of my monitors (a cheap Samsung 16:9 and the LG TV) I get an image. It's ever so slightly unstable - sharp but constantly buzzing up and down just minutely. It's fine for a short spell, but if I tried hours of coding on it like I did with my Beeb back in the day I'd probably lose my sight. On one other monitor (the 4:3) I got an 'out of range' message and on my Dell the image showed, but off the edge of the display and fuzzy as hell. But hey, it's all usable.

BTW, the TV has a SCART input. Is there any reason why that might be more stable, using an RGB-to-Scart lead? You can tell I know nothing about video, so I'lm clutching at straws here.

ken.boak 2017-09-24 14:26:07 UTC #55

Hi All,

I found that several PS/2 keyboards would give a brief flash of their LEDs when powered by 3.3V - and I believe this to be normal behaviour.

I think the keyboard needs to be issued a command from the host to turn on those LEDS, in response to a caps lock, num lock or scroll lock key being pressed. The keyboard does not light these LEDs automatically - it needs to be told to do so.

Last weekend we found that both HP model KB-0316 and Microsoft keyboards worked fine with BlackIce

Ken

Folknology 2017-09-24 14:59:37 UTC #56

BTW ST do have a Host library for simple classes including HID not sure if this works with STM32l433 yet:

http://www.st.com/content/ccc/resource/technical/document/user_manual/b8/5a/28/c2/cf/b6/47/d6/DM00105256.pdf/files/DM00105256.pdf/jcr:content/translations/en.DM00105256.pdf

*Update I just looked in STMCubeMx and could not find any Host options so perhaps this is for different chips
** It's for the chips that have an extra built in PHY

regards
Al

tony1tf 2017-09-26 15:45:40 UTC #57

Hi BigEd

Thanks for the info on the MMFS commands. I downloaded the utilities from Dave's github , and was able to read the MMB file on my Macbook. I found a free "disc" after all the games - number 314, and was able to copy the .ssd file there. When I use "dinfo" I can see the files:

Catalogue for Disk 314: 2048INS
Disk title: 2048INS (1) Disk size: &320 - 200K
Boot Option: 3 (EXEC) File count: 5

Filename: Lck Lo.add Ex.add Length Sct
$.CODE L 002300 002300 000CA6 013
$.CHARS L 000C00 000C00 000100 012
$.2048 L 001100 008023 000881 009
$.2048INS L 001900 008023 0005FF 003
$.!BOOT L 000000 000000 000030 002

However, I can't find how to load it on the BBC emulation. I can *dcat and get disc 314 listed.
But can't work out the syntax to load and run it.

Tony

hoglet 2017-09-26 16:18:10 UTC #58

The following will "mount" image 314 on drive 0.

*DIN 0 314

There's complete documentation for MMFS here.

tony1tf 2017-09-26 16:53:22 UTC #59

Hi Dave

Thank you for the info. Although your documentation is all there, my understanding wasn't. I could not understand what all the disc were. The penny has just dropped that the MMS file acts like a stack of discs which have to be inserted or "mounted" - I didn't understand what the DIN command did, but now I do. I can now play Eben Upton's BASIC version of "2048" - thanks again.

Tony

disneysw 2017-09-29 18:39:46 UTC #60

Thank you for that.

I was wondering why the audo level on the adapter board I just built was so low!