Neon6502 - Compact Replica of Acolyte

[AndrewP]

sburrow wrote:

"It freakin' works!" - Adrian Black

Please excuse my workplace mess... as I display some Mandelbrot! [ See attached. ]

First, a short story: I was sitting at the desk, staring at the schematics, back to the other desk, probing whatever I could with the 'scope, all in futility. My daughter came into the room, and I said, "Hey, this board isn't working, what is wrong with it?" holding it up for her to see. She looked at it and said, "I think it's a connection problem." I looked at one of those chips I had to bend the pins to make fit the footprint, and it *looked* fine to me. Hm. I had to leave to go to Wed night church. I came home, turned on the soldering iron, and after 5 minutes of reglobbing that beautiful tin/lead mixture all over the place, BOOM, it now works! I brought my daughter in to see it, told her that she helped me, and asked her what she wanted as a reward for helping me fix it. Without hesitation, she said, "I want a Switch 2!" Uh oh!

Yep, so that 'dip' in the data lines was an improper soldering job on improperly fitting chips on an improperly sized footprint with improperly small pads. Go figure.

I swear, the next time things just don't make sense, its because of something like this. Mark my words!!!

One issue: The picture is just dirty. It's not flickering, but it has major streaks and discoloring. I wanted light blue and orange, but I got dark blue and red. Not sure if that's a resistor issue, a power issue, or a 74HC166 issue, or what. [ Probably a solder issue!!! ] I'll have to play with it a bit.

So this is a bodge-less design! That's neat I DO want to bodge one tiny thing for the buttons, but it is purely aesthetics, not required.

Thanks for putting up with me everyone. That was one trippy few days. Next up is a 3D printed case and then Tetris!

Chad

Awesome, I'm glad it's working now!

I do a bunch of surface mounter soldering now and buying a digital microscope was a life saver:

51MP HDMI Microscope Camera Digital Video Camera Industrial Electronic USB Microscope 120X C Mount Lens with Remote Control

It's surprisingly capable for something so much cheaper than a professional microscope - the specs are all bullshit but, yeah, still capable. My eyesight is good but I've found pads that aren't soldered when I swore they were; and tiny solder bridges that I had not seen even with a magnifying glass.

All that aside...

Something still feels odd about the behaviour you were seeing and I'd hesitate to say it's a canary chip*. But that 25ns spike that doesn't align with anything that the board is doing is ... I dunno.

If you have a second 65C02 and a hot air gun and the time I'd be really interested to know if the same thing happened with a different '02.

But before that I'd suggest re-soldering all the pins on the '02 and then cleaning out all the flux-crud that you can get to to. Also check that the decoupling caps are soldered down and not just a blob of solder hanging in the air.

The STP getting triggered is still baffling and makes me think there is some spikey signal getting into the '02 and that its enough to change levels and cause the internal stop flop to trigger. It's fixed and stable now but I suspect there may have been more than one problem contributing.

I guess the question is: how much time - if any - do you want to spend working out what the problem is/was.

*Typically most times I've blamed a bad IC and replaced it to have the board start working I have then swapped the 'bad' one back on again and then it's worked. i.e. it was a placement or solder problem I hadn't seen

[AndrewP]

gfoot wrote:

I'm glad it's working now - subtle connection issues can be hard to diagnose!

For the resistors, I presume you have one channel connected to R through a 510ohm resistor, another connected to B through a 510ohm resistor, and both channels connected to G through 1k resistors? The white levels do look good though. Bear in mind that the signal is 50-ohm terminated at the receiving end, so the output voltage will be 5V * 50 / (510+50) which is only 0.44V. The peak level ought to be more like 0.7V, as far as I know. Around 350ohms would probably be better for R and B, and 2x700ohms for G.

However the horizontal banding makes me think that the levels aren't consistently black during the blanking period. Is it possible your "visible" signal is unstable? I'd look closely at that, and the output signal levels during blanking (especially the green signal).

I posted under George so I'm just quoting him to bring the message back onto the page.

[sburrow]

AndrewP wrote:

I guess the question is: how much time - if any - do you want to spend working out what the problem is/was.

I'm going to have to look into a microscope at some point I'm using super magnifying glasses right now. How much time? I don't know honestly. I'm ok taking time on this, but then again I really want to move on to another project also. I'm torn Thank you Andrew!

gfoot wrote:

Is it possible your "visible" signal is unstable?

Genius! Literally genius, George, thank you so much! See attached now. Yep, the VISIBLE pin was not soldered right, again. Gosh, I really need to check my footprints. None of this would have happened if I paid more careful attention to my footprints.

gfoot wrote:

Bear in mind that the signal is 50-ohm terminated at the receiving end

I thought it was 70 or 80 ohms??? I had been doing this with that assumption for years now, many years.

gfoot wrote:

The peak level ought to be more like 0.7V,

Totally agree. That's why I target that value. See my Falstad testing circuit:

https://www.falstad.com/circuit/circuit ... NqxECDSOQA

Anyways, yes, once, again it was an unsoldered pin. Having to bend my pins and make it fit improper footprints have been the bane of this project, I tell you!

Alright crisp now. Time for Tetris

Thank you everyone, and especially George. You were an initial inspiration for me George, and for that, truly thank you.

Chad

[gfoot]

sburrow wrote:

gfoot wrote:

Is it possible your "visible" signal is unstable?

Genius! Literally genius, George, thank you so much! See attached now. Yep, the VISIBLE pin was not soldered right, again. Gosh, I really need to check my footprints. None of this would have happened if I paid more careful attention to my footprints.

Ah it's not genius, I've just run into similar display issues before!

For the footprints, I think it's recommended to use the "long pads" ones for hand soldering in general, and they would be more tolerant of variations in package width too.

Quote:

gfoot wrote:

Bear in mind that the signal is 50-ohm terminated at the receiving end

I thought it was 70 or 80 ohms??? I had been doing this with that assumption for years now, many years.

Oops yes of course, it's 75 ohm terminated, I jumped into the calculation with the wrong value!

Good luck with the tetris. Is this system software-compatible with the previous one or are there differences to work around?

[sburrow]

gfoot wrote:

For the footprints, I think it's recommended to use the "long pads" ones for hand soldering in general, and they would be more tolerant of variations in package width too.

It was my fault. I knew the '245 and the '377 would be bigger. But I forgot to measure from the datasheet. However the '00 was unexpected, I just got the wrong package apparently. Yes, long pads are awesome, again I just forgot (or figured "of course this will be fine" as usual).

gfoot wrote:

Good luck with the tetris. Is this system software-compatible with the previous one or are there differences to work around?

My previous version would be 99% compatible. However, I'm making it brand new just because it's fun to code. No need to rush this project, just having fun Nevertheless, I'm sure I'll get it done in a couple of days, and then I'll remake Space Invaders or something.

See attached. I got the Tetris grid up and ready! I also see that my 'visible' signal is shifted by one bit, I might want to adjust that soon-ish.

Thank you

Chad

[gfoot]

That picture reminds me, I saw a physical puzzle video on YouTube recently where you had to fit the digits from 0 to 9 in a 11x11 grid. The digits were rendered in 3x5 cells like yours:

Code: Select all

*** * *** *** * * *** *** *** *** ***
* * *   *   * * * *   *   * * * * * *
* * * *** *** *** *** ***   * *** ***
* * * *     *   *   * * *   * * *   *
*** * *** ***   * *** ***   * *** ***

More to the point though, maybe this kind of pentomino-like shape-fitting game is another thing you could add to your collection.

[BigEd]

(A fine puzzle, thanks!)

[sburrow]

Well, I have a basic Tetris prototype. I have all the pieces, I have them colliding, I even have them bumping off the walls if you wanted to. I also did a psuedo random number generator: Current = 5 * Previous + 17, I had used it before some years ago on my Acolyte projects. See attached from my simulator. [ Wow, a simulator makes prototyping so much easier! ]

What I do not have is button inputs. You will laugh, but I am supposed to push them through a shift register into the /SO pin, which is flickering at 6 MHz through glue logic. To load and/or shift I need to write to ROM, that's it. I don't even have the logic implemented in my simulator yet, so I'm kind of stuck until I do something about that. Hopefully it works!

Well, there's progress. See, I knew I'd finish this too darned early...

Chad

[sburrow]

Ack! I had to add a bodge wire!!!

So the /SO pin was toggling too fast, and the appropriate level was not being caught on the PHI2-rising edge. I connected it's logic to a slower clock and presto, it worked. See attached.

I now have working buttons on the PCB (as well as the simulator). After cleaning up of some code, my Tetris clone is basically done. I just need to add a way to display the score and next piece. I tried some chunky blocks and it looked ugly so I'm going to use a font bitmap similar to what I've done in the past. I should also randomize the pieces in 'bags' instead of just raw random numbers. I could also add fancy wall kicks and other things maybe. Lastly, I really want to change the graphics for the blocks themselves so they look better then a single solid color, maybe even make it bigger?

After getting done with most of it, I realized that the way I access some of the data is really gross. But it works and that's fine for now.

If you want to see my code and everything else, here again is my GitHub repo: https://github.com/stevenchadburrow/Neon6502

I'll probably come back to this project later. I'm going to be busy this Thanksgiving week, so for now this is good enough.

Thank you everyone!

Chad

EDIT: Fun facts, it seems the code for Tetris is just over 5 x 256 = 1280 bytes, the pieces take up 320 bytes, and the program uses 32 bytes in zero page RAM and 256 bytes in additional RAM. I could definitely optimize the code size for sure, if I accessed the pieces better it would definitely get down to 1024 bytes. It's just fun to see what a minimal Tetris game would require in ROM and RAM

[sburrow]

Link to my Youtube Short:

https://www.youtube.com/shorts/nDpJQxdZJzY

Chad

[sburrow]

Alright! Done with Tetris! I attached the (uncommented) code and a screenshot. Again, my GitHub link is here: https://github.com/stevenchadburrow/Neon6502.

I added a score, variable speed, next piece, and random bag. I also revamped the blocks to make them look better. Lots of little glitches fixed also, and a few hacks to just make it work. Obviously this isn't the best version of Tetris ever, but it's good enough for 3 days of coding from zero. Has it only been 3 days? *shrug*

In the meantime I also designed the 3D printed enclosure and buttons. Except for one cross-eyed moment, everything fits flush, so that's nice I used the same color palette that it displays in VGA: blue and orange! I then showed it to my daughter and she said, "Where's the screen?" I said, this only plugs into the monitor. I then showed my wife who said, "Where's the screen?" Ah! Next time...

Whelp, there we have it. NOW I gotta do other things this Thanksgiving week, probably shouldn't have gone this far already! Busy busy.

What's next with Neon6502? Either Space Invaders, or something else. Or nothing else? Not sure, I really want to jump back into the PIC24 for a little bit while I wait for the PIC32CZ to come out (if it ever will!). We'll see.

Thank you everyone! Another wonderful 6502 project, complete though not finished! I couldn't have done this and everything else I do without y'all's initial help and encouragement.

Chad

[BigDumbDinosaur]

sburrow wrote:

Alright! Done with Tetris! I attached the (uncommented) code and a screenshot...

No wonder the source file opened so fast.    A comment would die of abject loneliness in that code.     

[barnacle]

Aw, it's got some comments. They're all huddling together at the beginning, for warmth.

Nicely done, Chad. Just one question: where's the screen?

Neil

[sburrow]

BigDumbDinosaur wrote:

No wonder the source file opened so fast. A comment would die of abject loneliness in that code.

Haha, hilarious!

barnacle wrote:

Aw, it's got some comments. They're all huddling together at the beginning, for warmth.
Nicely done, Chad. Just one question: where's the screen?
Neil

Haha! You guys literally make me lol Thank you for that.

See attached for my latest high score, 212 lines! It was moving really fast near the end, I think it maxes out the speed at 180 lines or so. I just couldn't keep up!

Thanks

Chad