Battlestar Gallactic Grounds

Hello and welcome to the macro fat engineering podcast where your hosts Parker, Noma and Steven Gregg, this is episode number 118. So, like last couple podcasts before we start, we got a Twitter chat this May 4 be with you. Friday at 1pm Central. We're gonna be talking about PCB fixture design. And then the meetup info is May 23 6pm. At Mac prep HQ in Houston. We have Brandon from particle. He's going to give a talk about IoT fundamentals, probably some stuff with particle devices. And then there's the Houston hardware Happy Hour, which the first one will be this Thursday. So if you're in Houston come by, it's May 3 at slowpokes, 6pm. Come by, bring hacks and hang out. I think Steven is going to be there with his synthesizers that we built. Yep. I say we I don't like the enclosure. That's it.

It's currently maple and it was stained and it was all you designed it? Yeah. You you had a partner. So yeah, we're gonna be having hopefully some open synthesizers or people just come and play.

Yeah. So yeah. So Steven, if it still works, if it still works we haven't had the funny thing is he said that hasn't been turned on since the podcast. We had it on here.

Well, I built the other one. The better. Much better one. Yeah. So that's, that's that that's coming play. Have fun.

Yeah. So hopefully we have more people show up with their hacks. And, you know, I think I'm gonna bring one of my old Nintendo portables. So I got the thing about that guy. Find the charger. I don't know.

Oh, that's the year your Nintendo NAS with that? Yep. It the whole cartridge fits in the back. Yeah, yeah. Yeah, yeah.

Yeah. The problem with that is, well, it works. I just haven't found the charger in like ages. It's a standard 7.4 volt, two cell lithium charger, I just got to find it.

We should make. Of course, I'm going to say we should do something and we're probably not going to do it. But it'd be cool to have a secondary port that has a slave screen and controller such that a second player could plug in. And they don't have the process or anything like that. It's just a screen in a controller. And then you can do Techmo Super Bowl to player at the slowpokes.

So the funny thing about that is back when I was in that, like, I guess you can call it scene. Like there's a whole community designing hacking portal consoles to make them portable.

They're like Ben Heck kind of Yeah, yeah. But it's actually what's called

The Ben Heck forms. Well, go. So the thing about this was we actually, the first standard I ever designed was called the N 64, or something. But it was a standard that use an Ethernet connector. So you could basically have two and 64 portables. And if you had this connector on it, and you implemented the circuitry, right, you could plug an Ethernet connector, and an Ethernet connector into the other one. And one would be set up as the master and it would slave your buttons to the other system and your screen to the other system and see that

so the slaves processor would just say, Hey, give me data. I'm just gonna throw it up.

In 64 inside would be disconnected. Oh, I asked the buttons, low control buttons and then the screen over that connector. Okay, because then 64 used like three pins for the controller data, power and ground. And so it was like you just sent data across. And yeah, it was actually really cool. I don't think we ever built anything with it. But that was like the first standard. I kind of dig that. It's gonna be on like my web server. So that's like the

old days of the Gameboy Advance with the way you had to have the Advanced link cable. Yep, and it had that goofy like pigtail that had you know three connections on the end of the pigtail. And you'd have this like weird octopus mess of cables to play four player games. Yeah, like you remember Legend of Zelda Four Swords, you could play a four player and I did it once. I actually got four people together and played that but it was just like an absolute mess. It was it was fun. Like

so I had to pick up that standard because that's the first standard

you write like a white paper standard ah, it was a

true up on paper and then like scan it in, but it has like, this is how you implemented blah blah blah blah blah. And just thinking about it is like kind of like cringy because like we like argued about that the standard like online like intense arguing and arguing

about how to pass Nintendo data over an Ethernet cable was

like competing standards and stuff. Yeah, eventually no one built it. Basically no one just

I'm you know, I'm going to contact IEEE and ask if they can implement this in

IPC and 64.

Yeah, that dashing 64 Yeah, that's right. The Mario standard Mario.

Ah, okay, so it's even even

a little bit of an offshoot there, actually. So I will be working on what I'm about to talk about, actually, right after the podcast. I'm going to be fixing a buddy's amp. Actually, guy who works at McWrap. Here. Jerry McDaniel. You may have talked to him. A lot

of our customers know him. Yeah, he's a one man.

What is his role? I mean, what is his actual title? I call him. Oh, Director of delight. God, that's,

I call him the customer, Wrangler. Customer. Yeah, all of these

are accurate terms. So he's actually had this app for a super long time. And it's very, he's been talking to me for years about like, Well, yeah, maybe not years, but a long time about fixing it. And the funny thing is, it actually works. But it picks up radio signals. So just like sitting there, and what's really funny about it is always picks up 100 stations, like you go to your jam room, everyone turns on their amps, and it just you just start hearing Tejano it's, it's hilarious.

What's, uh, what's the ZZ Top heard it on the X? Oh, yeah. So y'all don't know heard it on the ZZ Top song that is about listening to radio. So this is back in like the 80s and 70s, where you would have radio stations in Mexico, and they would illegally broadcast by basically turning up their power past like FCC standards. And they would broadcast probably the biggest guy. And yeah, basically just drown everyone out. I mean, it's how like, was it the pirate radio movie, which was the boats or whatever it was? They went

offshore and broadcasting from there. Yeah, that's, you know, we could listen to like, rock and roll back. And yeah.

And back in Britain in the 50s, or whatever. Yeah. So yeah, that's it was kind of similar. And I guess popular enough, that ZZ Top wrote a song about that. So hopefully, all listeners know who ZZ Top is.

I pretty sure they know who ZZ Top is, I guess right in if you don't know what ZZ Top? No, go to YouTube immediately. And go listen to the whole discography of ZZ Top. That's your homework for the week. If you've never heard them, so yeah, this it's funny. The picking up radio is actually a an issue in many, many tube amps. Because what what's funny

is, but to clarify, that's not what's supposed to do. Yes, yeah,

that that is not the intent. And so So here's, here's the thing that's funny about any tube amp, your guitar plug plugs into a quarter inch jack, and the signal right down a wire that goes literally directly into it rides lightning, yep. Right into the first tube, like that's the input of every tube amp out there. Now, there's almost always and I say like, almost always been like 99% of the time, there's a one meg resistor to ground. But that's pretty much it unless you have a series resistance. So your signal is like pumped directly into the first tube. And inside that tube of the vacuum, and it's your signal goes into like just a mesh of wires inside of that, that tube. So really, the input impedance of that tube is purely defined by that one meg resistor that's on the output of that tube. If you don't have a resistor in series with it, the length of the cable that goes inside of the amp, and combined with that one meg resistor, happens to fit within radio frequency pickup range. So you basically have an antenna. And the way they solve this is they just put a resistor in line to just swamp out. Effectively, what you're doing is the input capacitance on a tube is about 100, Pico farads. Once you've worn multiplied it will multiply it by its amplification. Okay, it's like one or two Pico farads in reality, but it acts as 100. Once you multiply it by the game,

you talked about active capacitors, couple podcasts. Yeah, it's

called the Miller capacitance. So the input capacitor is actually it's it, like I said, it's small, but the way the tube thinks about it is it's

the guy brought us active filters and like beer,

yeah. Highlife tubes. So, so yeah, deal between that the in series resistance and the virtual Miller capacitance on the front end, you're basically making a radio frequency filter. The downfall of that is that the entirety of the noise of an amp is swamped by the Johnson noise of that first resistor. So Johnson NOISE for those who don't know, like every resistor out there just produces noise from heat effectively. So thermal noise, right, right. So yeah, like the electrons inside of a resistor, they just move Even if they're, you know, like just in room temperature, they're jiggling around. And so it produces its own, I guess not produces but it but there's a there's a noise that is produced by thermal movement jitter Yeah, jitter, basically, and it's random, but it's there, and it's dependent upon the resistance. So you would want lower resistance. But in order to make a proper radio filter on the front end, you usually do something in the range of like 68k. But since that's right at the input, 100% of the noise generated by that resistor is amplified all the way through the amp. And if you're talking about a guitar amp, or you're just hammering 1000s of times gain, you get a lot of hiss. And a lot of it's not hum, it's hiss, or popping that on the output. So typically, you try to keep that resistor between like 10k and 60k. The lower you go, the worse the radio filter gets, the higher you go, the better it gets, but you start to get more noise. So

what about those people that use wireless guitars? Does that get rid of that

then? It does, because you because with a wireless thing, you're going to have a real low driving impedance, okay? But a guitar has an incredibly high driving impedance like most guitars have between 250k and 500, and K pots on the output. And those pots are turned all the way up because guitars. So the output impedance of a guitar plus all the weird capacitance and inductance of cable, which, you know, one guy has a six foot cable and another guy has a 20 foot cable and they're different coax and so all of that like plays into

so what about doing like a fully shielded cable? Or is that not matter? On the inside? You know? No, like your guitar cable? Fully shield? Oh, every guitar cable is fully shield. Okay, so and that doesn't prevent the antenna pick up? Well, no, but

but shielded cable is a big capacitor, right? So you're adding, you're adding Okay, so you have you have the inductances of the coils inside the guitar. And then you have a handful of resistors for tone. Yep, and volume. And then you have this big monster cable that is a huge capacitor that goes into, you know, blah, blah, blah, blah, keep going down the line. You know, it's like a horrible homework problem back in college. Remember, like impedance networks and all that crap? Yeah. So you know, all of that plays into your frequency response. But you know, even even a small like, half inch trace on a PCB, along with one or two pico ferrets can actually make a radio antenna. So it's, it's more of a matter of just like swapping it with resistors so after after this podcast, I'm actually going to break open the up. And basically, I think his amp doesn't actually have that resistor. That's why he's picking up radio. Too close to the border here. Yeah, yeah, exactly. The X is broadcasting too loud. Yeah, it's broadcasting on Orange amps. Free

worldwide. Yeah, in Texas.

So yeah, I'm gonna I'm gonna just mess around with that resistor and I'm gonna buy us the tubes, which you know, that's a whole nother topic. We can talk about another time. Yeah, some brand new tubes are here. Yeah, brand new e 34. ELLs? Those are those are some nice crunchy little tubes.

You know, are these actually brand new or

brand new box has never been open? You can you can break them. Oh, Slovak Republic. Yeah. Well, there's a of I think there's two factories in the world. Well, I mean, there's more, but there's two, like commercial factories. Yeah. No, I'm sorry, three. There's Czech Republic. There's Russia. And there's China that do commercial tubes. There's small ones speckled around things. But yeah, because it came from the

US manufacturers that make tubes but they're for like satellites and actual radio antennas and stuff. Well, no, they're ginormous.

In most, most radio stations still run on tubes.

Like the actual broadcast to know we talked about that? Yeah, a couple was a long, long time ago. Yeah. Because the only way to because you need a ginormous amplifier to pump out 50 kilowatts, and you need usually a single stage to do that shoot where you're talking more

like a megawatt. I mean, like a lot of what a lot of what Yeah,

that's a new as a Steve Craig standard.

I should just make a new app called a lot of what the SK

s Steve Craig standard. A lot of what I like that

so yeah, that's that's what I'm gonna do. Maybe we'll maybe we'll take some pictures. Yeah, throw them up there. Have some fun. You can see the guts of an app. Yep. What you've been up to bargain

so I finished the deck article. Part three should go live around the time this podcast comes out, I guess. So. That's done. It basically goes over like how to make your PCB better for like production testing by like adding Pogo pin contacts and how to design a fixture With pogo pins and stuff like that, so that's going to come out. And then I started working on part four, which is like writing the code and actually saying, Oh, it works. And actually, spoiler alert, it did work, which was good. So I spent like 30 minutes writing code today and got it to work. Nice. Nice. So for every one of the fixture work out of the box, that's like four years of learning how to design the fixture, and knowing what tolerances matter when building physical devices. So yeah, I'm gonna have a podcast. So

did you write anything about no surface mount pogo pins?

I didn't say I just said you could get point. I didn't say that by said I like these because they're through hole. And they have a gate. It could be interpreted as yeah, there's it's the no Max brand, because they have a through hole but not just a straight shot. It's got that step. So they sit on their PCB. Yeah, like a flange? Yeah. So that way, it's always set with the right offset. So you always have pogo pins level. Right. Right. That's the big thing.

Is having the pogo pins level. Yeah. And I was saying don't use surface mount. Because we've had some experiences with surface mount.

Yeah, the first fixture we ever built.

Yeah, it was, well, the first fixture that was pogo pins for macro fab. Yes. And that that just didn't go as well. It sounds

like such a great idea. Well, okay,

so there is a you could use them if you have them supported in some way. Yeah. Or if they go through like if they went to like a plastic block, or some

island or going through the plastic block by did the throw anyways? Yeah, because I remember when we did the surface mount ones is they always drifted a bit. Oh, yeah. And they, and they always they diverse. refloat vertical. They're always tilted a bit. Yep. Because the surface tension would fall up and kind of push them over.

They're just super, super sensitive to paste amount. And your pad dimension I mentioned, if your pads are not perfect on there, they just slide around. Yeah, there's nothing to keep them in place. Yeah. So but it's a one pin surface mount component. And

this is the thing with a fixture is you want to design it for reliability. And it's usually a one off NRA charge. So it's like, Okay, I'm going to spend an extra $10 and labor to put through whole pogo pins on it. What do you do?

Well, okay, so the thing that I could see the surface mount pogo pins working for is like, you know, this is gonna show me not knowing my Macintosh crap. But the, you know, the they're like, magnetic, the magnetic. Yeah, I could see, you know, a surface mount board where it's like, encased in an aluminum, okay, like clips in. Like, that might be a good situation where they could work. Especially like if they were soldered together with a shroud holding them. Yep, that would be fine. Like

you had a reflow resistance. Temperature wise plastic. Yep, yep. Yeah, cuz yeah,

that could work. But, but the price is the same in almost like, yeah, so use the rule, just do homeless.

So I don't remember the part number off the top of my head. It's like 30 digits long. So of course, yeah, I'll put it in the podcast notes and just check out the article. So yeah, part four will come out probably next week, or the week after that. And it's basically like, it works. Here's the code. And in like a video of it like working like showing like, it's how fast it is. Because that's the thing is, the whole point was to speed up your programming process. So instead of having because I could just make cables that plugged in, and all that stuff. And sure that been fine. But you know, plugging in cables takes you know, 10 to 15 seconds, whereas I just put the thing on the board and hit a button and the Arduino hits it with i square C and I to S and Bam, done. You gotta test it in like five seconds. Yeah,

yeah. You gotta love it when you get assembly instructions from a customer. And they're like, plug these three cables into the side of the board. And then and they say how long it takes after that, and it's like 1.5 seconds. Come on.

Oh, yeah. And then. So that chronicles blah, blah, subpart, four come out. And that's like the last thing for the stack. So that's cool. Basically, I finally three of that article series. I don't know what the next article series will be. But we'll figure it out. I think it's basically working on knowledge base a lot, because there's a lot of like, articles that we can run like capsulated edges and like drawing a cut out correctly for all the different EDA tools and stuff like that. I'm basically gonna finish up the eagle stuff first, because that's what I know. And then I'm going to learn KY CAD, which two pits but

I've ran into sprint layout this week. I actually found a suit. So there was a there was a board I was really interested in on a forum that I frequent I was like, Oh, cool. The guy gave his layout file. And I downloaded and it's a sprint layout file. Have you ever used ever heard of it? It's apparently it's another EDA tool. It's 50 bucks. Yeah, I think 50 bucks for the whole thing. And it kind of sucks because unless you pay 50 bucks, you can't convert it into a different format. And you cannot export Gerber's. So it's basically like, if, if I want to do anything to his board, in terms of like ordering Gerber's or modifying it, I'd have to pay 50 bucks for Sprint layout. And I can get the demo version so I can view his boards. But it's just like, oh, man, that kind of sucks. Look into it. Yeah, take a look at it. I hadn't even heard about it until just the other day.

Yeah. So basically, KY CAD would be next, to learn KY CAD, I'm gonna basically redraw like the macro, watch Dahlia and get that rolling. Then trying to do Altium and Altium. If you're listening, I'd like to have a copy a license

to your friends. It's only two copies. Yeah, only two copies and make them unlimited for the rest of our life, please. It's only two.

So yeah. That's why we work on next. So DEF CON 26. Yeah, that's that's this August, beginning of August. I booked my plane tickets. Nice. So I'll be there. You're gonna come Steven,

I will do my best to make my way out there. Well, we'll have to see. I haven't really been looking that far out right now. Yeah, I guess it's not that far out. But

that's what that's why I realized.

Oh, wait. Yeah, I may. I may have to see if I can get my way out there. Yeah.

So yeah, I booked my plane tickets in I'm looking for like, getting a hotel room. I was looking hotel rooms aren't that bad per day? Like you can get 80 bucks a day? Really? Yeah, it's just right off the strand. And now like, I'm like, Oh, that's not too scummy? No, no. So I think the idea with DEF CON 26 for Mac fab is going to be is I'm going to basically like, do lots of map episodes. Ah, and I've been working on a badge. But it's not gonna be ready. Like, it's a next year, but it's a next year badge. It's not gonna be ready. So this year, I'm going to you, I'm going to build a quote, shitty add on, unquote. That's what they call actually, it's a shitty add on connector. And there's like a there's a hackaday.io. Like, standard for this. Really? Yeah. And like, the connectors like offset at like, a weird angle and all the scores. Yeah, because it's a shitty standard. Yeah. And so I was going to do is I was going to design a map that a map shitty add on. I don't know really what's gonna do yet, but it's probably gonna have blinking lights, and the bus has I squared C, but you usually have to get with like the badge designer and put your eisbaer C code on it. So it's like, fuck that. That's like too much work. And so I might go to like that idea we had with a voice modulator. So like, it had, like a microphone on the back, like put a men's microphone, get a pizza on the front end. And then so you can talk into it. And so if someone didn't want their voice to be recorded,

have a little switch on the side. You could do like, octave up or octave down or do like goofy stuff. Yeah.

And just make it super simple. You know, you know, put like if I could use like a 40 cent FM eight, because it has an analog input. Sample the microphone, and then oh, no, it's men's. It's probably a square seat. So don't need that. And then just basically WAM Dr. Mako.

He's really bad DSP. Yeah. Yeah. And just like, that'd be perfectly like sample at like 1k or something like that.

But so if you if you go on the map, an interview on the map, you get one of these. Oh, that's like that to get people to

do I get one of those. I guess I need to be a guest on the map.

Oh, you can get one just have to come out and get one. So I don't know how many I'm gonna make yet probably. I mean, I'm pretty much gonna go out there. And that's like, what I'm going to do is like, if you haven't

been out there neither night and so it sounds like it'd be a good trip for like research. Yeah. Yeah. See what it's

like. Yeah, I want to go out there talk to a lot of people record a lot. Like, try to get everyone's story. I want to go to a lot of talks. Because like, you know, that's my thing with hardware, because the good thing about DEF CON is there's a lot of hardware stuff now. And so, don't do that. So that's gonna be a lot of fun. Nice. And then the Gameboy project. I always I was like two weeks Go I was like, Oh yeah, that's gonna be my new project I'm going to work on now I'm working on this like badge thing. But I upgraded to the newest version Eagle

hashtag add life. Yeah,

I upgraded the newest version Eagle version nine. And so I've been doing the Gameboy board in that. And the first thing I'm doing is I'm using their new feature, which is called Design blocks, which is an actual design element like you can design FPGA with old supporting hardware, and then actually routed out with planes and stuff. And you can say that, that's cool. So you can just drop into your schematic and it drops that whole segment into your board. That's pretty awesome. So that's like the best thing I think cat, Autodesk has done. To eagle is like that. There's like fancy routing crap, too. But it actually looks really impressive when you look at the gifts they have in their like, press release. So I tried it out. It's pretty good. But it does not do sight exiting out of pads. Really, yeah, it will just go straight out. And so we'll go out like at a 45 degree angle, if it wants to. Oh, it's like, oh, it looks ugly. So needs an option, Eagle, cat soft. Autodesk if you're listening if you have an option to turn on, so it will just always go out 90 degrees out of your pad.

Yeah. So So does it? Does it have an impact on bill of materials? Like will it say one circuit block? Or will it still like break out? It breaks it out? breaks it all? So it puts all those parts in? And what does it lump them together? And say like, Hey, these are all part of this circuit block? I don't know yet. Because because that would be cool. If there was an option to do that, where it could say, like, one of these function blocks is these parts, you know, it sounds like sub Billa materials,

I don't know, at the check, see what the what the short, they call it the hierarchy? Yeah, cuz they have like a weird hierarchy. And you can figure that by looking at their ULP. So don't just look at the new up documentation and see if like, they have designed blocks, I guess they do probably, and see if you can pull that out.

You know, actually, I don't know this about Eagle, I ran into this the other day in dip trace. So in DipTrace, you can create different pages. And you can have a multi page schematic. And I really like that, because I'll put my processor on one page, my power supply on another page, I'll chunk it all out. But one thing that sucks is with dip trace that you cannot do, you can't make a PCB that includes anything less than all of the pages. So in other words, like, let's say I wanted my PCB to be its own individual, I'm sorry, my power supply to be its own individual PCB, I couldn't just select that page and say, only make a PCB with this page, I'd have to make a whole nother file, which isn't a big deal. You just copy it over. But I would love it. If I could say like, these three pages or one PCB, these two pages are an Oh,

you're kind of building a internal product and your EDA tool. Exactly.

I think that would be really cool. And I think Altium can do that. Probably. I think ultimately Eagle Eagle can't Okay. Yeah. And I wouldn't, I wouldn't expect that level of, I guess professionalism until you get into the like, big guys. Yeah. But I really wish dip trace could do that. That would be really convenient.

That'd be basically like a, your board part would have pages?

Effectively. Yeah, yeah. Cuz because I mean, the way I do it now is I named my files, the name of the project. And then I named each board like top board or bottom board or whatever that board is, but I have to have. But in order to make that work, I have to have multiple files flying around. It's not a big deal. It's more of an exercise in like, File Allocation in how you structure those

things. I've never actually designed really a product that had multiple boards, and it Oh, no, I think the back one of the products I designed for dynamic perception way back in the day had two boards. One was like the control board, or with the microcontroller and all that stuff on it. And then we built a I had a sub board that had buttons on it. And so that went to the front of the case. Yeah. And then there was a flex cable that was returning, I just had to equal files for it.

Yeah, in which that works great. It's just when you have a board that has lots of inner board connections. It's nice to have them right next to each other or in the same files that you can guarantee that you know, this goes to that. Yeah, kind of thing. So no, no, no, whatever. I mean, it's once again, it's just more of an exercise on making sure all your stuff is right.

Yeah. Cool. Yeah.

Oh, actually, I wanted to state I watched the video just the other day. Where Ben Heck made the big Gameboy thing. Yeah, using your code. And I would suggest to all of our listeners, if you haven't seen that, go to YouTube and watch The Ben Heck episode, because this actually is Ben Heck, using The Parker's code that he's been talking about here is just a cool thing to go check out. I guess it's just a big monitor really. But that's but you could you can see it in action. Yeah.

The funny thing about it is Ben's Gameboy he made is like the world's second largest Gameboy made when someone really wants slightly bigger but the thing probably the person who made the I can't marry some Swedish guy, probably. His is not in the correct proportions.

Oh, Ben is probably

one to one perfectly one to one scale. Yeah, he's kind of anal about that. So I really want to do is I want to make a for this year's Houston. Maker Fair. I want to build a four foot by eight foot Gameboy. Oh, I'd be so heavy yet make it ginormous. And then basically put built in wheels in the back and blah, blah, blah. Wait, could

you play like DDR style? That's always gonna do as I was gonna build

a scale and the S pad. Yeah. So you need two people to control it. One person on the D pad and one person on the buttons. Nice. Yeah. That's great. So that's one of my that's like my, like, mid summer project. When it's like, hot as crap outside. I'll be in the garage melting.

You're gonna have to find a giant monitor that has one to one. Scale. Like it has to be a square.

No, you just bought a box it. Oh, that's cheating. You can't find a monitor like that.

That's why I say it's

a big one of the old projector TVs. Yeah, because they were lighter. And pop that up there. Unless I can get like a big like 56 inch TV for free. Get a

big deal P and make your own little hole like reflective system in there. Oh, that sounds terrible. Could be a pain in the ass.

Be so I'm gonna build this ginormous thing. And yeah, I think I should make the cartridges replaceable.

You should make like, full sized cartridges like to scale the scale. Yeah, but it still has a little EEPROM and big carnage. Yeah. Yeah. A lot of gold pins like Monster gold pins, like the size of your hand. Yeah.

I think I'll just have like a fake cartridge in it. Yeah. Macro fab cartridge. So yeah, that's that's what I want to do for the Houston Maker Faire. Oh, and then I have a pin hiccup date. I'm just full of a lot going on. The Raspberry Cup, the Raspberry Pi working pretty well. On video. I bought a book called The Raspberry Pi GPU audio video programming by Jan newmarch.

Man, that's a page.

The first chapter is like, what the Raspberry Pi is about? And I'm like, oh, yeah, I get this. The second chapter is like, the third line is like, here's the code. And yeah, we were able to get some video running like, right away. Straight API calls to the GPU on the Raspberry Pi.

Oh, wow. That's cool. That's really where the magic of the Raspberry Pi is.

The GPU is this thing is the CPU on the PI is like from 97. And but the GPU is actually pretty good. Yeah. And yeah, direct access calls that GPU is super fast, like, you would hope so yeah. Basically, like you click a button, you click enter to run the command and meetly pops up cool, decodes. And so we're going to get on the next big thing is get video switching working really well. And that's with the SD card random access, get that working? And then pretty much set to go. Awesome. So more on that when probably when we get some, like a tech demo working. We'll probably talk more about that. So yeah. Our photon

on the RFO

and let's not do anything else.

I'm not doing as much as you. Yeah, sure. So actually, I actually kind of prepared a little bit of a question. And this is more of a discussion more to figure out. I guess you could say such a way that you do some PCB stuff. Okay. Because I've actually been reading up a lot on this topic recently. And I wanted to get your opinion on things. How do you or do you take a specific approach to grounding on your PCB?

Hmm. So do you need to start

go for it? Alright, so

usually, I try to do every, every single component on one side. I guess we're talking about two layer boards.

I'm talking about PCBs. Okay, so it's

a two layer board. Yeah, I almost 100% Put all the parts on top side, one ground plane on the bottom, and then you drop down as close as possible to wherever the ground needs to go. So like if you have a bypass cap, we try to go as close. You move your VA as close as possible to that pad, and you drop down.

Okay, so yeah, you're doing the like the plane

Yep, method playing punch. That's actually we should call that. Yeah, yeah. PNP.

And I've totally done that. No, I bet probably actually, I've done that most. I think my stat is

what I normally do like 100 If it's too late board 100% of time. So I do like the dashboard is that

you try to keep that ground plane.

Yeah, wide open, wide open. Never. I will actually like redesign. Like, go back to the schematic redesign move pins around GPIO around, just to make the traces. Right. So I don't have to go to I don't have to break that point. Gotcha. Yeah. And then the five volt or one or Vcc 3.3 volts usually is a run that like on the perimeter on the top layer, and then go up in kind of like a branch fashion. That will that's correct. But it looks correct when I do it. And so

and it works. It works with low noise. And so it's on a four layer board to dedicate one layer to ground.

And so it's the same thing is ones ground and one's power. Yeah. And so you have two siblings? Yeah. So you do the same thing is I used to try to put as many parts as possible on one side. Usually, if I do a four layer board, it's there's a reason because I need super low noise on like the power like FPGA or I'm doing

or fine pitch things. Very

fine picture to BGA is basically yeah. Because you usually I can get away with doing like the ring power line. Yeah, like the pin hack is like a six layer board because all the power planes like all over the place, or where they we need five volts, and we need 3.3 volts. And so it was getting a little hairy trying to draw a ginormous bat trace, like a, you know, a 200 mil trace across the back of the board. Yeah, yeah. It's like, Ah, screw it. And that. And that volumes, doing a six letter board is only like an extra 10 bucks.

So yeah, it's worth it in that case. Yeah. So yeah, and one of the reasons why I've been asking this, because I've been on sort of, like a big research phase on to what what is the best method? Well, topology and scheme for for a lot of the things that I really like the star ground. Well, and actually, so get this I found, I found in general that there's three different schools of mind. And there's, there's positives to all of them. There's the the plane and plunge guys, like and, and you and I have been those for the majority of our stuff. I of course, you know, in like my tube amps, I don't have that, you know, like, I'll do wire here and there, then they're star ground at the other extreme. So putting on the plane ground is just like you have one big chunk of ground and you go directly to it as fast as fast as possible. And star ground means that every ground point in your entire system has one individual dedicated wire to one point. And it's very different. Now there is a third thought that's kind of in between, and it's called galactic grounds. I've never heard of that. I love that.

I think I've heard a branching or tree style.

Well, and it's sort of that way. And in fact, it probably is the Select a lot to collect. Again, it's super great, because instead of Battlestar grounds, yeah, BGG galactic star ground or ski is, that's such a great name, I love that. What you do is you take circuit block elements that all it doesn't matter if they're grounds inter intermingle. So take for instance, like if you have an op amp, and it has some, you know, inputs and outputs that somehow go to ground, those are okay to all clumped together into one wire, and then to send that to a star. So that's a galaxy microcontroller with a bunch of bypass caps. That's another galaxy. Gotcha. And those can all go individually. Because what happens, the whole reason why you do this is, you know, traces have resistance. Yep. Even though it's really low, they have some. So if current flows into a ground, you actually get a voltage potential patch of ground or caution trace, yeah, right, right across the plane. Exactly. So if you have high currents going through there, you can actually raise the ground of an entire other circuit block, and that can have all kinds of issues. Yeah, oscillation, noise and all kinds of crap. So if you have like a really low noise situation, you can Galaxy all of their low noise stuff together and send it to the star and all your dirty stuff you like you're that's kind

of like, like separating out planes. Yeah, it is.

The one thing that I've been really kind of digging into though is planes Actually, don't. The way electrons flow in a plane is not necessarily the path of least resistance. No, it's the path of least inductance correct impedance, impedance. Yeah, which which equates to inductance. In that case, because there's not a lot, not a huge amount of capacitance in that situation. And so, think about it this way, if you have a slow signal, it's usually better to give it its own individual ground line. And if you have a fast signal, it's usually good to give it a huge plane. Because the and what I mean by fast is, you know, digital signals, you know, that have fast transitions, like a square wave kind of thing, it will find its own best path to ground, it don't give it a plane, but a slow signal doesn't, you know, doesn't typically like that. And that can actually cause some some issues. So kind of a mixture of planes and galaxies, together gives you sort of the best situation. So, but I am kind of curious, and I want to soon I've kind of been playing around with some ideas, I want to try to do a true star PCB, where I have, like a point right in the middle of the of it, and I dedicate an entire plane or an entire layer on the back. And instead of planing it, it just has gazillions of lines going into this one point. Because let me you know, I'll keep talking about I'm gonna look up an image, I saw a star ground image the other day of someone who did that, and it probably doesn't, like, make your circuit work that 30 times better, or anything like that, it probably doesn't even make it work any better. Probably not, but, but it's still kind of like a fun exercise

to do, you know, it'd be really nice to be able to test all this stuff,

you know, an anechoic chamber here. And an amp that can read like, Pico volts or something like that. Yeah, I do, actually, I've always wanted to get a distortion analyzer. You know, you don't really find them very often for like, cheap, and you don't really use them very often. Coming, like, if you're a guy who's, you know, designing analog chips for TI, you have to use them. But if you're a guy at home, like you don't need that, but it still be fun to have some time, you know? I don't know. It's like, so I was just curious what your thought so

I actually, um, if I have an analog front end, like I have this board I designed called the octo prover, which is an eight channel thermocouple device. And its whole analog section has eight, you know, thermocouple readers. And so each one has its own dedicated ground plane that connects up to a main trace that goes to the main ground. So that's kind of galaxy, I guess, there. So yeah, I do understand that. That's actually a really good concept.

Yeah, yeah. And the way, the way I've been kind of, like, conceptualizing it is, you have, like, you have like a lake for your city. And that lake feeds like water towers. And then those water towers feed homes, and the homes are like your individual circuit blocks. And their water would actually feed back to the water towers, and the water towers would feed back to the lake, you don't want the homes necessarily feeding back to the lake, or feeding to other homes, or something like that. You want to keep them in those like specific loops. So keep your loops tight. You know, if you have a bulk capacitor that feeds a op amp, you want the return current from the op amp to go back to the capacitor, not back to some other random ground. Yeah. So I found that image I'm gonna get that to park you see that, like that is that is a star ground like, on this board, someone dedicated an entire side, they put a big monster circle in the middle, and all the grounds go to that one circle. So it's just traces everywhere to that. So this person was really whoever designed this was really strict about their star grounding. Yeah. The post that that's pretty good. Yeah, yeah, I'll shoot it off to you.

Alright, so I guess we go on to the next RFO. Yeah. So this is one that you found. Yeah. I saw

this earlier today. And I was like, this is this is super cool. I thought this would be really fun to talk about. So there's a new Arduino ish board out that's called the snow the SN O. And actually, I don't remember why it was called that. It has it's an acronym for something. Regardless, this is an Arduino that actually

super naked ostrich.

Exactly. That's, that's precisely what it is. I actually found this on Hackaday. Yeah, there's a Hackaday article. So you can go check it out there. But this is an Arduino that is basically Arduino plus FPGA.

He basically wrote some FPGA code that simulates a Arduino platform,

right? And it's sort of on like a little dev board stick. So the thing that's cool about it is you can still write in the Arduino IDE. Yep. To this so it acts like an Arduino. But it gives you a handful of FPGA blocks to play with. So it's not as hard as getting into like real FPS. GA stuff. And in fact, I should I should mention, the article was written by Al Williams who's been on the podcast before. Because like every time there's an FPGA article on, cuz he's way into it. But But ya know, so I thought that was super cool to have this FPGA. Now I did see that there was some limitations to it. Like on a normal FPGA you get however many blocks are available inside. And even a small FPGA has like, gobs of blocks that you can play with. This one is a lot more limited,

because most of it is dedicated to this Arduino thing will, right

and the way I kind of see it or understand it is that you don't necessarily get access to the actual FPGA blocks, you get kind of access to like, Arduino ised blocks. So it's still like, it's still an abstraction. They're still pulling you away from the stuff but at least it gives you like a an initial idea on FPGA stuff. So I guess if you wanted to make some, some logic blocks in there, then then you could probably pull that off. But you know, if you're wanting to implement another core, using Arduino, you know that that's not going to happen on something like this. Yeah. But you know, if you need to, like hammer out some data in a nanosecond, I bet you could do it.

Yeah. And it's all open source. Ness. Right? Yeah. Super cool. And then the third RFO is the analog rich MCU shoots for sensor nodes. And I thought this was really cool, too.

Yeah, yeah. So found this one on electronics. weekly.com. So this is a they had a quick little, like, Buzz article about this chip. And normally, those kinds of things are just like, okay, they're trying to sell something. But this one actually has a really unique aspect about it that I haven't seen before. Maybe there maybe it's out there. I've Well, I mean, I'm sure it is

seen something like this, but not like, this is like the feature that sells this chip. Yeah, this is something that's kind of like, added on. And it doesn't really work too well. But this is like the main feature for this is a pic 16 F 18 446. For all of those who care. Yeah, it's made by micro Atmel or micro mal micromill.

Microchip. There's no microchip in my mind. It's, it's a it's a picture. But what's cool about it is it has a special sleep function, that you can put the whole core to sleep, but you can still let the ADC run while it's sleeping. And so it's not going to have to do some kind of funky jazz where it comes up out of sleep. If it detects something and then it has to fire up the ADC. Sample. Yeah, and then sample. Yeah, the ADC can continue to sample during sleep. And in fact, you can wake up the processor, based on the ADC based on a value that's different. That's way different. You don't see that. Because like usually, it's like, I mean, with every microcontroller, you wake it up. If anything happens, you know, with this, you can say like, oh, only warn me if it if the threshold is above a certain level. And that's really cool. Because you can, you can still like you could use this in a quote, safety mode, you know, where like, all the values beneath this, I don't care about like a temperature or something don't

actually just be good for what is like is actually safety applications for sensing. Like chemicals. Yeah, like sulfur, because above a certain ppm. So first will kill you. And so a lot of people, you know, I used to work in the oil field, so you'd have a, a sulfur sensor, right? And when it would get above a certain you know, I think I think it was sulfur. I think it's sulfur or methane or Yeah, something like whatever. But now, you know, you'd have to replace the battery like every month, right? Because it was awake all the time. Sniffing Yeah. But if you had you know, your your microcontroller sleeping the entire time waiting for the sulfur to get to a certain level.

Yeah, because so if you have even if I mean this, this is a great situation, what the here's the thing, they're selling this as like a sensor MCU it's specific for low power sensor applications. So think of if you have a passive sensor, and even like take, I don't know, How about how about like a microphone, and you want the ADC to only pop up when it hears a high enough volume or something like that. You can save power on the processor and dedicate your power on to actually sampling.

I think it's sulfur dioxide.

i That sounds like something that could kill you.

Yeah, yeah, it's got oxide in it.

So I don't know I thought I thought that was super cool, though. And I haven't seen that before.

I haven't seen that kind of dedicated, analog, you know, ADC kind of stuff before.

The thing that I'm most curious about is how do you set up like sleep threshold? And can you add anything more to it? So in other words, like, can you add multiple thresholds where it does something if it goes beneath avoid value or above a value? Can you add, like, do something like that? Or can you have it where it's doing some low level calculation on that value above and beyond and only wakes up the processor if blah, blah, blah, happens? Like what? What is the possibilities? And with that, I bet you it just pull the pin if x value is reached, you know, something like that. That's probably the lowest power way to do it. But, but it's super cool. And this, this actual article talks about a little dev stick that you can get. Yeah, so it's not just the just the pack, you get a little dev tech play with. So go check it out. Yep. So I think that's, that's it. Is that gonna wrap it up? Yeah. So that was the macro fab engineering podcast. We were your host, Stephen Craig and Parker Dohmen. Take it easy guys later everyone.

Thank you. Yes, you our listener for downloading our show. If you have a cool idea, project or topic that you want Steven and I to discuss, tweet us at macro febrile illness at podcast at macro calm. And if you're in Houston, come to our hardware happy hour this Thursday. And also check out our Slack channel. We'll be continuing discussion about the podcast. This tiny Arduino in the analog rich MCU that Steven really loves. Now, that pig 16 We have well be talking about that on Slack channel. So go and visit us there. And if you're not subscribed to the podcast yet, click that subscribe button. That way you get the latest episode right when it releases and please review us wherever you listen as it helps the show. stay visible. helps new listeners find us