Tile Data PCB - VGA from Scratch - Part 14

[@weirdboyjim]

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[@akkudakkupl]

You don't need to key the power connectors. Just make them 3 pin, two grounds on there outside pins, power on the inside pin. You can use 2 wire cables with 3 pin headers, just put power in the center, ground on either outside pin and you are done ;-)

[@weirdboyjim]

That is an excellent suggestion!

[@mbeware]

That is an excellent idea! I'll implement that from now on in my projects. Thanks!

[@rimmersbryggeri]

Isnt that essentially how USB was made reversible

[@JohnScherer]

Nicely done James. It’s always nice when a board works straight away.

[@weirdboyjim]

Thanks John! I'm always a but nervous powering for the first time.

[@OscarSommerbo]

It is 10:30 on a Wednesday morning and a James Sharman video drops!! Screw it, I am getting a beer.

[@weirdboyjim]

Should I feel bad?

[@OscarSommerbo]

@@weirdboyjim Of course not! I am a grown human making my own poor decisions. 😁

[@khatharrmalkavian3306]

It's so satisfying to watch things go from multi-breadboard networks of wire to sleek, compact PCBs.

[@weirdboyjim]

Glad you like! But how would you feel if I went strait to pcb?

[@khatharrmalkavian3306]

I'd be vicariously nervous, lol. The breadboarding is much more agile for proof of concept. It does have the signal speed limitations though, so for high bandwidth stuff it may not be an option.

[@Stabby666]

For dev/test boards I just use a p-channel MOSFET circuit on the power input - this has the benefit of only allowing the power through in the correct polarity, while not having the voltage drop of a typical diode method. For the cost of a few pence for a little SOT-23 chip, diode and resistor, it's nice easy bit of protection (saved me a few times!)

[@weirdboyjim]

Interesting, I'll give that some thought. It would be easier to justify if I was making larger modules.

[@Stabby666]

@@weirdboyjim Yes, I guess it depends if the end goal is to offer the boards as a kit. With the backplane obviously that almost completely negates issues, but if people are wiring the boards separately, then there will be inevitable puffs of magic smoke from some :) I have PCBA done in china for my production and prototype designs, with final assembly in the UK, and started adding more protection due to mistakes by people on the assembly line here. Some of the chips on my boards are pretty expensive though, and never seem to survive reverse polarity, so it's a bit different (also had problems with them using bench supplies to test, set to the wrong voltage, so also had to protect against that :) Great series by the way!

[@UnexpectedMaker]

Another great result James! Dodged a fast bullet with the power pins that time... your luck *must* be running low by now :)

[@weirdboyjim]

Thanks Seon! I always worry about that, although maybe I'm in luck credit after that mistake on the giant backplane board.

[@laser-sj]

Great work James. I love EASYEDA 😎

[@weirdboyjim]

It's a great tool with a low barrier to entry!

[@peter.stimpel]

Not so bad. Now I did not create too complex pcbs in the times where we had to trace lines for a pcb on paper, but I imagine your call "created quitze a challenge for myself" caused some different reaction at that times. EDA is a gift

[@weirdboyjim]

We are indeed spoiled! Not to mention high quality manufacturing at low price!

[@RealEngineer]

Great video as always!🎉

[@weirdboyjim]

Thanks!

[@NotMarkKnopfler]

Oh no. A James Sharman video. That's my morning writing C# code gone!

[@weirdboyjim]

My bad, sorry. 😉

[@FrankGevaerts]

Some nice progress!

[@weirdboyjim]

Thanks Frank!

[@m1geo]

Nice one James! And blimey, that Patreon list is growing healthily! 👌

[@weirdboyjim]

Thanks George!

[@stevedonkers9087]

I think the auto-router would've taken care of this in around two minutes. I would recommend it, I recently had a 6502 SBC board I designed in EasyEDA made and the auto-router was flawless (I checked it's work of course, but it was a 4-layer board and it was much easier to have it do the routing.)

[@weirdboyjim]

I really wouldn't want to attack a board like this with the auto router. I find the very process of routing it tends to identify some issues and I can adjust bits of the circuit in ways the autorouter can't. Besides, I'm not one for the easy path.

[@TurtleKwitty]

@@weirdboyjim More content doing it your way as well haha

[@inlywang8157]

Excellent work James,thanks

[@weirdboyjim]

Glad you enjoyed it

[@TonyBrooks1979]

Hey james. Still watching! 😊 i started your series of videos again... and i am continuing to work on mine. Tony

[@weirdboyjim]

Good to hear you are still finding my stuff interesting! Hope your build goes well!

[@yorgle]

Spectacular!

[@weirdboyjim]

Thanks Yorgle!

[@xombies]

Great video as always! Question for you, James. Once you've "finished" this build, are you planning to create one final PCB that combines every single PCB, so that you effectively only have one PCB for the entire project? It would be quite incredible if you did! The PCB work is my favorite part of this series, so seeing you put together one definitive full-build single PCB would be great to watch.

[@weirdboyjim]

It will stay as separate modules, but there will be a final combined backplane for all the vga modules to plug into. A final (fixed) backplane for all the cpu modules to plug into and a final backplane for all the other peripherals (UART, Audio, SNES controller etc..) to plug into.

[@m1geo]

There's a replacement controller for the hot plate you have. With better regulation, etc.

[@weirdboyjim]

Ohh, do you have a link for that? I've seen there is a more recent version but didn't know there was an upgrade. I've been thinking about trying to pull one of these apart and merge it with a reflow controller.

[@TheEmbeddedHobbyist]

Looking good except for the lack of magic smoke. The odd chip removing it's top with a loud bang was always followed by loud clapping from the other engineers in the lab, now days if it goes bang there's no one to notice unless i'm videoing it. 😞

[@weirdboyjim]

I'm very sorry for not failing well enough!

[@TheEmbeddedHobbyist]

@@weirdboyjim Maybe for next time throw in a few reversed biased tant's caps for that added WoW factor. 🙂

[@roboman2444]

This, combined with your recent ADC/DAC and synth audio, is just a few steps away from a (winning) demoscene prod.

[@weirdboyjim]

Thanks! Did you see my various Beam Racing demos?

[@TomStorey96]

Is it necessary to route traces between pads for GND and VCC if you're dropping vias to connect those pads to internal planes? Seems a bit redundant to me?

[@weirdboyjim]

I'm not an expert on this stuff, but someone who definitely knows more than me told me that vias should be regarded as having a greater resistance than a trace so if possible connect the power lines of chips to their decoupling directly.

[@TomStorey96]

​@@weirdboyjim Intriguing. Im not saying they are wrong, but every "professional" PCB Ive ever looked at doesnt seem to go to that trouble? A quick bit of googling and some calculations online seems to suggest 10-30mOhm is typical for vias, but an 8mil trace over 0.5inch is about the same (high 20's mOhm). Increase the trace width by a factor of 10 and the resistance drops by a factor of 10, so it would seem you really need fat traces for it to make much of a difference? Im sure there are applications where it matters, but that its one of those "if you know then you *need* to know" kind of things lol.

[@weirdboyjim]

@@TomStorey96 it’s not uncommon for me to get conflicting advice, it would surprise me if this advice was wrong but I may not be describing it right. I went back and looked at the pcb design, there really isn’t that much vcc/gnd traces beyond connecting to vias.

[@TomStorey96]

@@weirdboyjim Im sure you get all sorts of ideas and suggestions thrown at you. In the end, the important thing is that it works.

[@drivers99]

Edit: part 13 is (currently) missing from the VGA playlist (it shows “deleted” where 13 should be, but I see 13 in your full uploads list)

[@weirdboyjim]

I've fixed that. Thanks.

[@GameBacardi]

Good videos, like it.

[@weirdboyjim]

Glad you like it!

[@vitalian1980]

Great job! I want to make something similar only in my dreams. 😊

[@weirdboyjim]

I had very little electronics experience when I started, anyone can do this with some patience and practice!

[@m1geo]

Hey James! Why go to the effort of connecting power/ground up on L1 and L4 if you're adding internal power and ground planes?

[@m1geo]

Scrap that! You're only making 2-layer! 😁 Your "internal planes" comment confused me! If only I had waited 2 minutes longer! 😁

[@weirdboyjim]

The Tile Data board is 4 layer, the 2 internal layers are power and ground. I'm going to be honest George, knowing your experience I'm more inclined to think you question means I'm either explaining myself poorly or doing the wrong thing. I only get a connection to the internal planes from a via (or other plated hole) so I still have to make sure they are connected. I've also been advised that it's better to have a component side trace from the the decoupling direct to the power pins so I try and do that. Finally if I see a little blue rat line and a clear way to connect them I can't resist adding the trace even when I know a later via to the plane will do it.

[@twobob]

mint. winner winner

[@weirdboyjim]

Thanks twobob!

[@janhofmann3499]

Great work as always.. two questions: -what's the "JLCJLCJLCJLCJLCJLC" under the 7164 on the silk screen? -instead of designing the red breakout board, why not solder the pins "upwards" for testing and make a second pcb with the pins correctly downwards for the main build? depending on component cost, could be cheaper than a second pcb. thanks and greets from Germany..

[@weirdboyjim]

the "JLCJLC..." is a marker for JLCPCB as to where they can put their production serial number, if you check later in the video it's been replaced with a there own id for tracking the board through stages of production. You absolutely could do that with the PCB pins BUT this testing is as much about my soldering as the design itself so doing it that way doesn't cover all my test cases.

[@0LoneTech]

18:25 shows the JLC numbers

[@AppliedCryogenics]

I think a lot of game developers of the 8-Bit era would give up half of their pixel resolution to have a second, true tilemap layer for parallax scrolling. The SNES could do up to four if one could accept the palette limitations. The PC engine had only one tilemap layer, so developers had to stand on their heads to get anything resembling parallax, usually by defining a lot of extra tiles as animation frames, or line-scrolling tricks. I think this constituted a primary downfall of the PC engine.

[@weirdboyjim]

I wouldn't disagree with you. But how many of them would have been prepared to solder all the extra components that would be necessary? 😅

[@matambale]

I will believe in the awesome power of AI when an auto-router arrives that actually automatically routes something (edit: something dense). To be fair, perhaps the tools I've used weren't recent enough, or expensive enough.

[@weirdboyjim]

It does feel to me like Autorouters should be better than they are. If I had spare time I might take a crack at creating an open source one, it's a similer class of problem to group pathfinding in game development.

[@matambale]

@@weirdboyjim It certainly qualifies as an excellent puzzle to solve. (Edit: and that's a brilliant idea for a parent algorithm - perhaps a lot of code could be inherited)

[@gammongaming9081]

my dad saw this and said that his company uses autorouter. i now hate him.

[@weirdboyjim]

If it works it works, I wouldn't want to use it for the main circuit. But I did autoroute the test board I plug it into.