IO Peripheral PCB - IO from Scratch - Part 9

[@weirdboyjim]

Join us on Discord: discord.gg/jmf6M3z7XS Follow me on Twitter: twitter.com/WeirdBoyJim Support the channel on Patreon: www.patreon.com/JamesSharman Get your own PCB’s like this from the Video Sponsor: jlcpcb.com/?from=weirdboyjim

[@pdxjjb]

I found your "low key" endorsement of JLCPCB to be very winning, very convincing. It did not interfere with my appreciation of your video in any way. I hope they appreciate it! And I agree that your coverage of the "bodge" was very educational. All in all an excellent video.

[@weirdboyjim]

Glad you enjoyed it!" Looking forward to using the SD card particularly in future!

[@josephlunderville3195]

I've used JLC since years ago myself, I'm not the biggest customer but they've been perfectly reliable every time they've made something for me. It's nice to see an alternative to the universal stumping for PCBway who I'm sure are also fine, but are a bit pricier :)

[@Packbat]

Accepting a sponsorship from JLCPCB must have been the easiest choice you could have made in the entire build, what with the number of PCBs you've gotten from them over the years - glad they were willing to support the project! And sympathies on the bodge - it looks about as clean as it could get, though. Nicely measured wire lengths and everything.

[@weirdboyjim]

Indeed, a product you already use regularly is very easy!

[@nahkamursu]

i don't mind it at all, it's how i found em first place and been quite happy as their customer for keyboard pcb's :)

[@matambale]

"Too much decoupling" = "No room for any other parts" All this time I thought you were already sponsored by JLCPCB. It's a logical connection - they're great for this work and you've been demonstrating that from the start.

[@weirdboyjim]

One day I'll build a series of circuits to test / demo what effect various levels of decoupling have.

[@damianvila]

You know it's a great day when another video of the Sharmatronic 2000 (aka jam-1) arrives. 😄

[@weirdboyjim]

I'm glad you think so!

[@awesomecronk7183]

The routing and debugging have to be my favorite parts of each video. Thanks for sharing this project with us!

[@weirdboyjim]

Glad you enjoyed it! My stuff will always need plenty of debugging!

[@richfiles]

Congrats on getting the JLCPCB sponsorship! You've been a HUGE advocate for the quality of their product for ages, so it's good to see you rewarded for it! I used JLCPCB for a board back in 2021... Even ordered over Christmas, the turnaround was _shockingly_ fast, and the boards were perfect.

[@weirdboyjim]

Glad to hear your experience was good. I've just recorded a second video sponsererd by them.

[@Schwuuuuup]

I love how your video schedule is basically just the shiping cycle of Jlcpcb😉 And I don't mind the sponsorship ship. One thing to keep in mind though is, that many of us devour your content in the warm and fluffy feeling that "you are one of us" maybe one of the very best of us, but still I like to believe that "if I had the time and devotion, I could build (a crappy version of) this as well. This illusion would break if a sponsorship would feel as if you found an unlimited money glitch. Like using Tools no-one can afford or ordering PCBs in sizes and quantities worthy of a medium industrial company. With jlc I missed the button "make it as cheap as possible I'll add features later" so the tip about the stencils is VERY welcome

[@weirdboyjim]

Indeed! No real risk of me getting "unlimited money". I try to be very careful with the tools that I use to keep everything at the hobbyist level. Not sure I'd trust myself with the expensive stuff anyway!

[@SomeMorganSomewhere]

Yeah, the stencil size tip is one I give anybody I see who gets a full size stencil from JLC ;) (unfortunately certain other companies don't provide the option)

[@JanBruunAndersen]

A suggestion: Implement some kind of history mechanism in your CLI so you can easily repeat commands.

[@sparthir]

When he has storage fully up and running a terminal history file can be saved to it. 😊

[@weirdboyjim]

That would be useful, but you really need a more advanced line editor to use it. all tasks in the backlog!

[@JanBruunAndersen]

@@weirdboyjim - an interactive line editor is not required. Something like simple token substitution will go a long way. Like in Bash where '!!' will cause the last command to be executed. Or '!!:s^txt1^txt2' which will substitute txt1 with txt2.

[@RodHartzell]

Dude. Your videos inspire me. I am a software engineer and I enjoy working with electronics. This stuff you are doing is very informative and I love the way your brain works. I would be interested in building out this creation of yours. I suppose I will have to join your Patreon site.

[@weirdboyjim]

Thanks for the kind words! The discord is where you should join, I share various bits of my code etc.. there.

[@twobob]

Quality as ever. Topness, other superlatives

[@weirdboyjim]

Thanks twobob!

[@stompreaper]

It was a nice board and I agree that running down an issue and making it work occasionally is better than it always working first time. I enjoy the debugging process and fix cycle, feels like winning to me 😂

[@weirdboyjim]

Someones I feel debugging is the "real" skill to engineering!

[@Zadster]

Congrats on the sponsorship, a perfect match. A tip for using desoldering braid on fine pitch pads and delicate wires - don't drag the hot braid over the track, it can cause the track to lift. Just place the braid over the track and run the iron over the back of the braid.

[@weirdboyjim]

Thanks! The biggest improvement in de solder braid I found was to massage a little flux into the braid. I'll try not to drag it in future.

[@alabamacajun7791]

Been following the series from the beginning. Just amazing work.

[@weirdboyjim]

Glad you enjoy it!

[@Rouverius]

Great job. Actually, I was very impressed with your "bodge" to be honest. Exciting to see it all working.

[@weirdboyjim]

I'll be happier when I have a bodge free version! Be nice to have a whole section of the final system "done".

[@R.Daneel]

Great work. A home-brew processor reading an SD Card is damn impressive! Back in the day we used to use "Kynar" wire-wrap wire for bodges. Highly recommended if you can source a spool or two. Two great features: you could use the wire wrap tool to handle the wire like a micro-manipulator: you could strip the wire and then use the tool to loop the tiny wire around pins and such for soldering. Also - the insulation was, I think, Teflon, so it never melted. You could have the insulation right up against the bodge and it wouldn't shrink back under heat. Oh, and it's tiny of course. 28 gauge or so?

[@Zadster]

I have a reel of it in front of me! 30awg. Not teflon, but related to it.

[@SomeMorganSomewhere]

Unfortunately most of the "kynar" wire you find around these days isn't :/ it's not silver plated and the insulation is PVC or at least something other than a fluoropolymer because the insulation shrinks back on heating and it doesn't take solder very well... It IS fine for *actual* wirewrap work but not many people doing that these days. I have a couple of km of that stuff unfortunately so I do most of my bodges with enameled copper wire (aka magnet wire).

[@weirdboyjim]

What I'm using in this video was sold to as "Kynar Wrapping Wire" after someone recommended it in the comments of a previous video.

[@R.Daneel]

@@SomeMorganSomewhere Disappointing, but not surprising. I'm still using spools that are, ugh, about 30 years old. I'll be sure to not to use them wastefully. I won't keep them on the shelf with my "Tapcon" tape and "Ponasonic" capacitors...

[@TheRealWulfderay]

Fascinating. I particularly enjoyed the board layout part. I always feel so overwhelmed when I see that jumble of connections waiting for me to sort them out.

[@weirdboyjim]

Glad you enjoyed it!

[@TLang-el6sk]

Hi James, I always love to see your videos and all parts of your project are coming together really nicely. Just one thing I already noticed earlier regarding the decoupling: You placed the GND/VCC vias between the IC and the capacitor in most cases. This way you couple into the power planes before you even reach the decouplig capacitor. You should always go through the capacitor's pads before entering the power plane to get the full effect of the caps. For the switching speeds you have in your project it may not be a major issue but it improves overall signal and power integrity. I learned this myself from a collegue with long time experience...

[@weirdboyjim]

I can see the logic to that. I'll try and take note in future, but ground planes and fill can make that tough.

[@janschrder]

Thanks for taking us through this. I share Your view on faultfinding/correction versus construction. I also experience both processes as rewarding in different ways. I see no concerns regarding You beeing sponsered by JLCPCB. Based on what I've seen in Your videoes, I certainly would give them a try. As always, it's a pleasure seeing Your methodical way of working. Well done James. Thanks :-)

[@weirdboyjim]

Thanks! I always appreciate your support!

[@docwhogr]

JLC is the only honest youtube sponsor that i don't mind hearing about.. the worse are vpn providers and brilliant....

[@halfacanuck]

Honestly, I really enjoy the bodge videos! Bodging requires improvisation, creativity, finesse, and (sometimes) ingenuity, which makes for good and suspenseful viewing imo. Congrats on getting the SD card working! Opens up many possibilities. (Personally I'd have implemented a Forth kernel long ago. "What's a filesystem?" ~Forth users)

[@weirdboyjim]

I appreciate that! I do want to tidy up all the bodges before I call it done though.

[@theboot100]

Another great video James! Ive been waiting for the next one. Congrats on getting a sponsor! I use JLPCB for my boards. Your channel deserves a millions subs. Have you got any other plans for additional spi peripherals? Ethernet would be cool (although probably doesn't fit with your design goals)

[@weirdboyjim]

Thanks! No specific plans for spi peripherals for permanent integration, but there are a couple of experiments I want to run.

[@Otakutaru]

Really interesting that you finally got sponsored by them

[@weirdboyjim]

It had been a posibility for a while, felt like a far better option than many of my other sponsorship offers.

[@davejake771]

Hi James, I noticed cleaning up my boards with 99pc alcohol before reflow almost totally removed solder bridges issues. Also routing 4 layer boards I know is more expensive but saves you big time and generally improve your signal quality.

[@weirdboyjim]

These are 4 layer boards, although I use power and ground planes rather than use the extra layers for signals.

[@m1geo]

Nicely done James! 👍

[@weirdboyjim]

Thanks George!

[@laser-sj]

Love JLC !! 😎

[@weirdboyjim]

And JLC Loves you!

[@wiktordiy6033]

Hi James, I know, that floppy disks are not the best storage media, however i thin that floppy to spi or just simple floppy i card would be quite an interesting project.

[@weirdboyjim]

Interesting, but not something I'm likely to do in the near future. I can recommend my friend @GeorgeFoot's material on the subject kzbin.info/www/bejne/ql6mk5-Xo9Crp8U

[@danmerillat]

I've never done the trick with kapton tape on the pads I don't want to connect, but that's one I'll likely use in the future. A couple wires getting a first revision PCB working is pretty much the norm in the industry. Even in bigger designs with a team and design reviews it's always possible to miss something that looks obvious in hindsight. I've seen whitewires in finished products I've bought, sometimes it's cheaper to fix a few thousand boards than scrap them all. Bit of clever wire bending, a bit of kapton to hold them down and the fix will last forever.

[@weirdboyjim]

I'm pretty sure I separated those connections anyway but I wanted to make 100% sure!

[@your_utube]

The fun is in the bodge. Coming along nicely! Would they permit you to an event like the VCF events in the US? Does the UK have such events?

[@weirdboyjim]

I'm not aware of anything like VCF in the uk. It would be nice to go along to one of those one day.

[@joeysartain6056]

very interesting troubleshooting.

[@weirdboyjim]

Glad you like it!

[@AndyGoth111]

My go-to tool for cutting traces is an engraver

[@weirdboyjim]

Like a dremel type tool?

[@AndyGoth111]

@@weirdboyjim Yeah, except what I use is much smaller, runs off a AAA battery and is held like a pencil. The cutting tip is a tiny ball with a jagged surface. It works great for precisely making narrow, shallow cuts.

[@TheEmbeddedHobbyist]

I like to use very fine single core PTFE wire for my bodges. the insulation wont shrink back with the heat and can be laid down with ease and a little superglue holds in it place just fine. in the days of TPH components it could be fed behind the legs of DIL IC's to hold it down on the PCB. some of our devolvement PCB's may have flown with mods like this, if the unit had a painted blue band around the case it might have some bodges inside. we used a 4 band system on the equipment. 1. A painted Red band, was equipment was for rig use only. 2. A painted Blue band, was could be flown but a back up form of communications must be carried. 3. A sticky tape blue band, a production unit but full qualification has not been signed off yet. once it was fully certified the blue band could be removed. 4. No band, fully certified production unit. No bodges were allowed if the band was not painted on. Now I'm free to bodge to my hearts content, happy days 🙂

[@weirdboyjim]

Interesting. My concern with these longer bodges is catching them in the future! I'll do a board refresh before too long!

[@TheEmbeddedHobbyist]

@@weirdboyjim That's the problem with cheap PCB's. My last professional PCB's cost well over £1K for 75 ! So you have to make sure that there are no errors before sending them out. Check the circuit for error's, then check the Gerber's for any errors. like not enough via's for the required current overhead. check the right copper amount is specified on the PCB paper work. boy is sending a PCB off to PCBWay easer. 🙂

[@Biomancer81]

Yay new video!

[@weirdboyjim]

Hope it didn't disappoint!

[@Biomancer81]

@@weirdboyjim It did not.

[@erniepasveer8027]

Sometimes I find I learn more from my mistakes than my successes.

[@weirdboyjim]

I agree! Nice to have some things work first time occasionally though!

[@tinygriffy]

putting a piece of tape sticky side up under the stencil to lift it better is a nice trick ;)

[@weirdboyjim]

Yes! I might need to do that in future, smearing the paste first time was frustrating!

[@tinygriffy]

@@weirdboyjim at least it fluxed up the pcb real nice ;)

[@AppliedCryogenics]

I'd love to see an interface chip for hobbyists which can go on a classic 6800/8080 bus and give SDIO(!), SPI, and I2C! Patents be damned!

[@TSteffi]

For SPI: you can do that with 2 shift registers and a counter. And SD cards really just "speak" SPI on a hardware level. The problem is that the simplified specifications that the sd consortium puts out publicly doesn't have the sdio part in it. You have to be a company and member of the consortium to get that. I2C is much more difficult, because you have bi-directional signals that are sometimes output, sometimes input.

[@weirdboyjim]

Not sure about a chip, but it wouldn't be difficult to design a little module for that.

[@monad_tcp]

that was way tight fitting

[@weirdboyjim]

That's what happens when you try and cram stuff into the last space on the backplane!

[@jamesrivettcarnac]

I live your videos

[@captainboing]

excellent!. Sorry to see the bug in your PCB but on a personal note, I am pleased that if a man of your calibre can miss stuff, there is hope for me 😆

[@weirdboyjim]

Everyone makes mistakes! The real skill in this kind of stuff is often troubleshooting!

[@Stabby666]

I think pretty much every PCB designer has mixed up at least MISO and MOSI on a SPI bus, and RX/TX on a UART at least once. Sometimes even datasheets are ambiguous with some chips! UART especially, now I always label nets as "TX_FROM_MCU" and "RX_TO_MCU" etc so it's pretty obvious to me :) On JLCPCB, I've used them a lot for probably 5-6 years now - hundreds of boards per month with various designs, all PCBA. They're good EXCEPT when they make a mistake in production. In the latest case they'd loaded some BGA chips in the wrong rotation, and as I use a programming jig, I had 4 boards fail in a way that also destroyed the chips before I noticed and had to check all of the others. These were expensive chips that I'd ordered from another supplier, and stocked at JLC for production. It was a loss of 6 6-layer boards in total. I had no way to remove the BGAs and reflow them easily as they were densely packed with components on both sides. Each board cost around £100 in the batch, and they offered a £50 voucher, and refused to do any more. I've had similar issues previously, but not so costly, but they've never offered a refund that matched the cost of the boards. I have fixed issues myself previously, but my rate per hour means it's actually not worth it financially (I still do it in my spare time though). I also use PCBWay, and am moving the more expensive boards there - they do charge more but I haven't had an issue with them as yet - touch wood!

[@weirdboyjim]

Ahh, all those interesting mistakes I can add to my repertoire ;-)

[@GodmanchesterGoblin]

I once swapped ends on all bits of an 8 bit data bus due to LSB vs MSB naming conventions on data sheets. I managed to swap 8 tracks at 0.025 inch pitch in less than half an inch distance. But that was around 1987 or so - my eyes were a lot better back then. 😅

[@berntolovhellstrom8891]

Well done!

[@weirdboyjim]

Thanks!

[@NuttySwiss]

Love it. 😎

[@weirdboyjim]

Thanks!

[@-lolus-]

nice bodge

[@weirdboyjim]

Thanks!

[@bradywb98]

Ooh JLC sponsorship

[@weirdboyjim]

It felt like a logical fit.

[@billr3053]

I was wondering if the routing software would allow inspection and validation by simulating the logic, etc. before one commits to a physical board. I would have thought that with today’s sophisticated tools, that would be built in.

[@weirdboyjim]

That would be useful. But very difficult for a board like this where the simulation would need to know about the rest of the circuit to test it properly.

[@DavidLatham-productiondave]

I have a board i made where i had two spi pins transposed. Thr bodge has been working fine for close on 4 months. I do intend to roll another board but there is zero urgency.

[@weirdboyjim]

Some bodges feel very fragile, but some I just want to remove out of principle!

[@jerril42]

Nice board, ugly, but effective bodge. Sorry you have another board for the frame of shame. It was interesting to watch the diagnostics and bodge in action. Thanks James. Take care.

[@weirdboyjim]

Thanks Jerril! I have to decide if I'm going to try and de-solder the rtc chip, or get a new one!

[@jerril42]

@@weirdboyjim A bit of a risk of damage, but it would be nice if you could save it.

[@kokodin5895]

have you ever thought of using bottom layer as place for soldering stuff or do you decided you will only have one sided loads?

[@weirdboyjim]

I have done for some passives in the past. I generally avoid it as part of my project goals are to have everything on display.

[@peter.stimpel]

Sorry if I am alone with this opinion, but I love the bodge stuff, and I like true soldering videos much more over this reflow stuff. #ASMRSoldering And yes, I am aware of the advantages of reflowing ...

[@weirdboyjim]

I doubt I'll ever get to the point where I don't need to do a bunch of hand soldering work. It is quite rewarding but the reflow is good for getting lots of connections done with high reliability. A reflow oven would be better but at least with the hot plate I can record the process.

[@docwhogr]

i am wondering when JCL is gonna offer chip printing services....

[@weirdboyjim]

That would be interesting, although devices like fpga's fit many jobs you might want that for.

[@TSteffi]

This was really funny, because I made a very similar mistake recently. I'm working on a board for the RC2014 bus that has a TangNano 9k module as a VDP with HDMI output. And I because the data lines are named backwards in all the VDP datasheets, of course I wired the up the wrong way around. In my case, I didn't have to do a physical bodge, but could just swap the data pins in the FPGA.

[@weirdboyjim]

Ohh, a software fix for a hardware mistake. Nice!

[@TSteffi]

@@weirdboyjim only temporary of course. New boards will be made with the right wiring. But I can't afford that right now, so I had to fix it temporarily so I can keep working on the software for it

[@markrgreenlane]

James I’ve never seen it in all your videos but just wondered if you clean or wash them off camera to get rid of all the flux?

[@weirdboyjim]

I have a cheap ultrasonic cleaner off ebay but Haven't been cleaning the boards as routinely as I should.

[@markrgreenlane]

I did wonder if you did as that flux is a nasty acid and it’ll eat tracks and component legs.

[@jyvben1520]

37:54 tube says "no clean flux paste"

[@SomeMorganSomewhere]

@@markrgreenlane not all flux will do that, only highly active fluxes which aren't generally required on a fresh board like this, as jyvben1520 said it's no-clean so the only issue is an aesthetic one.

[@TLang-el6sk]

@@markrgreenlane Flux for use with electronics shouldn't be aggressive. Most modern flux is of the "no clean" type, so you can leave it on.

[@bobweiram6321]

You should definitely seek a role in the next Lord of the Rings movie. You'd be perfect for it.

[@weirdboyjim]

I'll get some pointy ears.

[@ossunaz-bz2k]

Is there an operating system installed on your computer?

[@weirdboyjim]

In this video you see me interacting with the Monitor program, you can think of those as kind of like a very basic OS.

[@khatharrmalkavian3306]

🤖The machine must grow. 🤖 So amazing to have seen it all come this far.

[@weirdboyjim]

Glad you are enjoying, but it can't grow too much! I'm running out of desk!

[@OscarSommerbo]

I don't know how much it matters, but the Vcc plane covers the area under the RTC chip. If the chip acts up, that might be the reason. I never mind sponsorships that are relevant. And it is a little sad making it took this long.

[@weirdboyjim]

Hmm, didn't think about masking of the vcc plane.

[@TLang-el6sk]

@@weirdboyjim There are different opinions about - what I usually do is laying a guard "negative trace" around the oscillator up to the oscillator pins of the RTC or uC. This way you have small isles with a single connection to GND/VCC below the critical lines. And these isles are not used as current return path. You load capacitors will then be connected to GND inside of these isles.

[@FrankGevaerts]

You've got too much decoupling! (Sorry, I had to)

[@weirdboyjim]

I'll see if I can pull some of the board with my pliers.

[@FrankGevaerts]

@@weirdboyjimyou mean, decouple the capacitors from the board?

[@damianvila]

Add MOAR caps!!!!