 And welcome to Desk of Lady Eta. Hey everybody and welcome to a Sunday night Desk of Lady Eta broadcasting at Lady Eta Clock, which right now is 10-ish. It's me, Lady Eta, this in my desk, with me, Mr. Lady Eta on camera control. Hi. Hi. So we've got, you know, some stuff to show off this week. Do we have any news and updates? News and updates this week. We have our usual set of shows and don't forget on Wednesdays now we have discount codes on Ask an Engineer because we're able to do that now. And that's eight o'clock to nine o'clock Eastern time. We have show and tell this week. We have JPs, product pick of the week. We have known Pedro's 3D Hangouts and then Scott's offer two weeks for deep dives, but you'll also be able to tune into JPs workshop on Thursday. So that's this week and more. What are you working on this week? Okay. Well, let's, you wanna show the calculator first? Yeah. I mean, I'll explain this a little bit. Okay. So one of the cool things that's going on right now is Python is being used in schools. And schools, maybe this isn't the so cool part. There is standardized testing and all the standardized tests that use these calculators. People are familiar with these HP calculators, TI calculators, Casio has one, WeStock one from NumWorks and all of them, all of them are now adding Python because Python is the most popular programming languages for kids. And so this is the new TI-84 Python edition. And this will be in the US soon. We got one from the UK, a little ahead of time. And it has... It's in German too. It has a European version of it. And France has already like said, Python's the future. We're doing everything Python, Python, Python, Python. So the cool thing about this one is this has a fork of circuit Python. We didn't know about this. They didn't ask us. We didn't tell them to do it. But we heard about it and we're like, that's really cool. So I have a set of... It's like bonkers cables, like a link cable. I have a set of questions that I sent over to TI. They're gonna send it over to their developers who worked on this. We're gonna find out why they chose a fork of circuit Python, what all of the things it can do. And this is kind of an unboxing. So this video will get five million views. But for calculator folks is a big deal. And then for circuit Python folks, it's a big deal too. So why don't you fire up this calculator and show a little Python tutorial. Yeah, this is kind of cool. So yeah, you can connect to your computer and you can do stuff. But let's just try it out. So this is the calculator. This comes with a case under the protector. Can I remove it Phil, or should I keep it on? Yeah, this is the unboxing. So now it's okay. That's great. This is super cool. That's nice. All right. Okay, so you turn it on with this on button here comes up and it says, I get shortcut menu, catalog. Okay, let's just click two for continue. And then now you're in like the normal calculator mode. So I can do like eight plus five. So like it's a nice graphical color TFT. Did you have to use any specific calculator in MIT? I was in grade and high school, I was specifically prohibited by my dad for having a graphing calculator. Really? I was not allowed in my household. Yep. Wow. I could have a calculator, but not a graphing calculator. And then at MIT, because I never had a graphing calculator, I just never got one. I did have the TI, there's a really great scientific engineering calculator that I had MIT. And I went through like three of them because I used them constantly and they were really, I don't remember the exact number off the top of my head, but it was definitely a TI calculator. And they were like, it was the one that was sold at the coop. Yeah. It was just like a nice long, it was a single-digit calculator. You know what I mean? It's for Wolfram to do a internet connected calculator that just like, it's a cloud calculator that's tied into Wolfram. Yeah. Right? I'm surprised it hasn't happened. I just used the Wolfram app on Android or iOS. Yeah. That could be it. Yeah. It's kind of like, once you have internet, you're like, you might want to talk. Yeah, I may as well, but it's kind of cool now. Okay. So next step, let's go to Python mode, which I'm trying to remember how you get into it. Just graph. You have to say Python three times. Python, Python, Python. So there's like all this plotting stuff. Yeah. You showed me some graphing on this before. Yeah. Now, of course, I'm trying to remember how I did it. Oh my goodness, I don't remember. Yeah. Well, you got into the mode before. Yeah. How was that? Did you read the book? No, I didn't. I just like typed something in. Maybe it was catalog. I think you have to do like a function key to. Yeah, there's the function key. Unfortunately, there's so many buttons. Well, yeah, it's a calculator. Let's see. I don't know where I'm at. I feel a little silly because I totally don't remember how I did it. Hold on. Like I totally practiced doing everything else, right? Hang out with us as we explore calculators. Yeah, plotting data, creating a menu. As we plot. Screen display, using mode, mode, math, radian. Oh, it was under apps, I think. Does it have TikTok? Yeah. But how did I get into the apps? Control C. Using menu. You can access many functions on the home page by selecting from menu. So from menu, select map. I feel a little silly. Well, just the unboxing. Yeah, but like there's too many mode. Mode? No, this is. Is it a synth? Is it a mode? Program, program. All right, focus back in on the calculator because all right, look at us. Don't worry, we'll clear that up and edit. No, it's fine. All right, so if you have to hit program, which is program, which is right here, hit that. And then there's CI basic and there's Python app. So maybe that's what I did. And then you hit enter. Great, Python app. And now we are in the Python app. Python app. So in this, you can put over the right a little bit. Like that? Well, yeah, look over here. Move it over a little bit. Sorry, yeah, I forgot that there's an inset. Yeah, OK, so this is, you can actually, so this is, you can go to files. So there's three files that come with it by default. There's the hello world, which is kind of what you expect. And then you can go into alpha lock mode and you can say, let's type in. And then one other thing, if you just search for TI-84. Yeah. TI-84 and Adafruit. You'll see my blog post about this. So there's a blog post that details all of this stuff. And we found out a couple of weeks ago, we got a calculator from the UK. These will be for US students soon. And then we'll have an interview with the TI dev team soon. Yeah, so this is the file itself. So you can edit this file if you want. So let's say I want to. What's my name? Yeah, that's a good idea. She's asking what's my. And then you want to. What is name? What is name? No, no, no, I have to. Because it's like your. What is love on this planet? Hold on. Let's see. My name. And then. And you want to hit run. Run. What's my name? And then you say. Let's see. T. Texas. My name's Tex. Texas. OK. OK. So yeah, you can edit. I'll say the one thing. It's a little annoying to type alpha numeric on this keypad. Because it has alpha numeric. But you have to focus your eyes to look at only the green and blue text. Well, here's the thing. But you have to program it on the computer and then you can choose that one. Yeah, this is used. There's a hub module and a rover module. It uses the control robot and stuff. So we're going to find out from TI themselves why they chose a fork of circuit Python and more. So that's it. This is a world premiere. No one's ever shown this on live video ever. And I don't think anyone will either. Yeah, so there's graph. So this is the graphing app. So one thing I thought was kind of neat and I think this is what they were really aiming for is they have a graphics driver that they wrote and see for this chip. So when you want to plot, they have a TI plotting object module that you can use to create these very nice plots and does all the graphing for you. So that part I thought was kind of nice because it took advantage of what Python's really good for, which is you do the really high speed stuff and see and then the configuration and abstraction level is in Python. So this is the TI plot. Let's see. So let's go to let's enter clear. OK, so go to editor. So you can see it's like they basically made a plotter. And I think it's like plot lib ish. And you can see you can clear the plot and then you can create a grid and then axes. And do pretty complicated plotting. So I thought that was kind of neat. They still have TI basic on there, but if you're going to have people write code in basic, you might as well give them Python. So the only thing I don't know for sure is what is the chip set that is running on this? I'm assuming it's a TI processor, but what TI processor? So maybe I'll open this up later and we can take a look at the chip because they had to port Python. The underlying C they had to port to this chip set. Yeah, one of my questions was like, is there another chip on there? Or is it like a port to the chip or chip is it? I think it's I think it's core. I think it's I don't think it's communicating with a separate chip. I think it's running. I mean, like to handle this is like a 320 by 240 screen or something. Yeah, something like that. Maybe I could make it 2.8 inch or 3 inch screen. So yeah, it's a nice build. Yeah, we can crack it open. We'll do that later. Yeah, OK, let's get the interview questions first before we crack open their calculator on video. Yeah. All right, so. Put this away. All right, any questions about that? No. Well, sort of, why did your dad not want you to have calculator? He thought it was not good for learning math because it makes you shortcut. He's like, you should be able to visualize it in your head. Yeah. Do you visualize it in your head? I do now visualize it in my head. Really? Yeah. So he was right? Yeah. All right. There you go. No, well, I mean, I don't know if I would necessarily like, you know, they're not necessary. I don't think graphing calculators are necessary. I do think that you want to use them as a way of verifying your visual imagery. The problem is that at some point you get to a state where you can't necessarily graph something. It's like, you have to have your mind be flexible enough to imagine what's going on because you can't plot it anymore. This can't do 3D plotting. But you know, you have to think about three dimensions at some point. OK. OK. So we're working on keyboards. OK, so next up we get the macro pad, the RP2040 macro pad. So this is the, let's shine some light on this. We can turn the light on the overhead itself. Yeah, that does exactly the opposite. It makes you make it darker. Really? Yeah. Yeah, that's right. Go ahead and turn it back on. It just sort of doesn't add. Yeah. So let me. Might be because the other hand, that's looking good. So you've got the RP2040, the USB-C, the OLED I changed out for one that has a FPC connector. So this connector, you flip it up and you can easily remove it. We got the reset button here and then the stomach QT over here, 12 buttons, three by four. I added a large buzzer. Although I don't know how useful it is. Kind of ways just like not place it. And then sockets for all the keys. For this version, I also, for the PCBs, I got a little mechanical support plate. So this is used, the switches are designed to use these mechanical support plates. So if you look, they have like a little lip here. You can kind of barely see it, but there's a little lip and you can tell that they're meant to snap into place. And once they snap in, they're nice. They're not like so tight, you can't remove them, but they're mechanically strong enough that you have to do a little bit of work to pop them out. I don't quite want to do it here, but you can pop them out. But then they, if you have a couple of them in a row, all of them together, even though they're not connected permanently to the bottom plate, they're strong enough that they don't, they're basically movable. Like you have enough of them that they, the friction fit of all of them together, pressing against the plate keeps them in place. And then there's a bottom plate as well. So this is also a PCB with the mounting holes that match up. And then this mounts to the bottom to create the three layer, Mechropad PCB. So this is like, you know, nice, safe bottom. And we can use some nice graphics here and like you can, you know, use screws to attach it through to the SMT Nets. And then you can put some bumpers on the bottom to make your Macro pads. So this one is running Arduino. So I always do bring up in Arduino first because I have more control over the code. And in this case, it was, you know, it's a handy thing to do because the OLEDs a little bit, has a little bit of weirdness to it that I was able to fix pretty easily in Arduino, but in circuit Python I have to do some core changes. So this, you know, you can see here, I have it printing out the key numbers if I press them all. It's three rows, four columns. No, three columns, four rows of keys. And then I have the encoder. And then up here, the rotary, I came out, this isn't soldered in. You can see the rotary knob changing numbers as I twist things and then there's a little I squared C scanner as well. So this is the Arduino code. So in Arduino, it's actually like, basically completely working. It's very fast, it's very easy to use. So I think in Arduino, well, I didn't know like that. In Arduino at least, it's totally done. So that's good. Kind of blown out this thing. I know, I don't know why. Well, I'm kind of fooled. I think you put the light on there before, whatever you did to make it. No, it's kind of. It's out of focus. Yeah, it just doesn't like what I'm doing here. It's like, it's too bright. So I'm gonna disconnect it. Okay, so that's our Arduino. It's like, why are you doing this to me? And then this is circuit Python. So like I mentioned, during the code, this one doesn't have the mechanical plate. So the switches that, you know, they can pop out a lot easier because they don't have that piece. Move it over the rail a little bit. Yeah, okay. So this one, I have a slightly different program so I can turn off all the LEDs. So for this one, I'm still working on the OLEDs. There's like this little line here on the right. That's because this OLED is actually not 128 by 64. The display is 128 by 64, but the chip is 132 by 64, which means that there's this like extra four, eight bytes of like dummy RAM memory that isn't being used. And so I just have to like, figure out what to do with the driver to make everything shift it over because when you get displays, it's not uncommon that the memory you have to address and the display are not aligned to zero, zero. Like the depending on how they lay it out, the display itself is inset into memory somehow. So again, Arduino is really easy. I, you know, I superclass it and then I just fixed that little offset thing but in circuit Python, like because this is in the core, I can't quite superclass it. So we have to add some keyword argument to help it know that this little chunk of memory should be skipped. But that said, you know, other than that, things are working and like the display, your stuff is going. So the last thing is the little buzzer. It does work, but I want to add a little RC filter to it to make it sound a little bit better. And audio playback for RP2040 isn't quite working. I mean, it kind of sort of works. Like it works enough for me to verify that like the speaker is connected correctly. But if I try to play an audio clip twice, it kind of like flips out a little bit. So it doesn't a hard fault, but we'll hopefully fix that in, in circuit Python 7.0 cause we're doing a lot of fixes and updates. So that's where the macro pads coming along. But I think I'm pretty much done. The hardware is all tested. So now it's just a matter of software fixes. And I just have like a little bit of like debugging here on the speaker to try to tune the RC filter to be really good. Because so far I haven't used this amplifier chip and piezo, the buzzer with a chip that does PWM audio. This doesn't have a DAC. It has a PWM output, but the PWM output's really fast. So you can actually get like not too shabby like audio, many audio clips playing from it, but you want to do a little bit of filtering first. So that's that. That's the macro pad. All right, any questions before we get into the great search? About the calculator, is the graphics library something that can be included in the circuit Python library? Would TI be able to do that? Or is it? Yeah, they'd have to add it. We don't have access to. All right, well, if they allow me follow up questions in my interview, I'll ask. I don't know if they're using the display IO underneath it, because again, there's no insight into the code, the code's a fork and it's not a published fork. But ideally, yeah, it would be cool to have that published because then it could be added to other people's projects so people can make their own DIY calculators. It would be really neat. That'd be super cool. Okay, let's head over to the great search. Okay, yep. The great search part to buy. Did you key an aid for it? Every single week, lady uses her powers of engineering for good and helps you find things on digikey.com. What are you searching for this week at Digikey? Okay, so let's go to the overhead and I'll show you this board design I'm working on. So this is a KB2040. So I designed this board, I think I showed off a couple of weeks ago. Finally got the PCBs in. So it's a USB-C RP2040 boards. This is the RP2040 and here's some power regulator stuff. And it's got cast-related pins and it's designed to be pro micro shape, which means that it can be used in keyboards. It's like it's specifically designed for use with keyboards that you would plug USB-C in and then it would generate the key commands while having LEDs or key matrix anodes and cathodes connected to this row of pins here. So the RP2040 we've chatted about in getting all the added peripherals that you need, the Q-Spy memory and the crystal and I got some tactile buttons. But one thing that was new on this board that I don't put on a lot of boards recently is a PTC fuse. So the pro micro has a resettable fuse on it and folks might be familiar with them because Arduino uses PTC fuses a lot, which is good because it helps protect the board and the computer. Now your USB hub and computer has PTC fuses inside of it. So if you ever plug in something to USB and actually over draws the current, it'll shut off and you might have to wait a couple of minutes, you might have to reboot the computer to get that port to come back. A PTC fuse is thermally, it's basically a resistor that's very temperature dependent. So as more current goes through it, it heats up and the resistance goes way, way high, like so high that it basically opens up and basically the fuse is open, cutting off power until this cools down. So it's kind of nice because unlike a glass or wire fuse, you don't have to worry about replacing it. Automatically, self heals, you can get these in different currents and voltages and of course they're pick and place friendly. It's a very slim PTC fuse here. So we want one, this one is a pretty chunky, looks like it's maybe an 18 by 12, 18, 12 sized PTC fuse. We want one that's much smaller. We're gonna have one that's about this big. It's 0806, we just don't have as much space on this board because I have to maintain the physical size. So this part here, this is the PTC fuse. So it's an 0805. I was like, can I fit an 01206? And the answer is no, there was just really no space. No, it was just completely jam packed in there. So let's go to the layout first real fast and we'll take a look at the, this is it. So this is the PTC fuse. If I get info on it, it's just called fuse and it's 0805 sized. So let's go for an 0805 Imperial sized fuse and we'll see what the options are. In specific, this one's gonna be connected to USB. So let's do something that's USB friendly. Okay, so too much stuff open here. Okay, so hold on, let's go to Digikey and let's search for PTC. So it's a positive temperature coefficient fuse, buys, close, fuse. Okay, so there's actually a whole category which I've used multiple times before PTC fuses. So go there. Okay, so now we have to decide what we want as our options. So the first thing is, well, obviously let's pick active and let's also pick in stock only and let's exclude marketplace so we're only looking at stuff that shipping directly from Digikey and in stock. Next up, the voltage max. So the voltage max is exactly what you think. What's the maximum voltage that you could have as the power supply that you're limiting? Now it's, you know, you're gonna see these in like chunks of like six, 12, and then, you know, 50 and then up to like a hundred. The larger the voltage, of course, the bigger the fuse. So if you're looking for price, you know, you might end up at a lower voltage, but since size is most important to us, we're probably gonna be limited to like that 06, sorry, that six volt or maybe even eight volt power maximum based on the size. So actually since our size is the most specific thing we have, let's go to surface mount and let's pick from the package size 0805, which is 2012 metric. So you can see these get very large and there's also through all size ones and there's whatever there's these like gigantic chunky square ones. So let's, let's apply. Okay, so now we're only gonna be looking at the 0805 ones. So the next thing is, right, so you can say we can pick the voltage max, but since all of them are above our maximum voltage which is USB, which is five volts, you know, we actually can leave this alone. So next question is the current hold and the current trip. And that's actually kind of the most important things you're gonna wanna think about. In general, the current trip is two times the current hold. Now, like I said, this is a temperature coefficient device, it's very temperature dependent. So you don't want it to add significantly different or poorly at like high or low temperatures. You want it to be somewhat consistent. So it's not like when it hits that number it'll immediately trip. There's gonna be some variation, right? So you wanna think of based on the usage current, how, you know, how much current is gonna be going through, is it continuous, is it spiking? Hold is like your continuous current and trip is like when it spikes up to that, that's when it's gonna shut off. Now, technically for USB, 500 milliamps is considered the standard hold current. I will say though that you can get ones with higher or lower. So let's look at 500 milliamps to one amp. And that's what the hold, cause it's like that's our like consistent power draw. Why would you even need that much for a keyboard? Well, maybe you have a lot of Neopixels on it. You have an OLED screen, you have a buzzer, like a lot of things are adding up before you know it, you're at about 500 milliamps. But you don't want of course to have the fuse so low that people are tripping it just on usage cause it'll make the device seem really flaky. So then let's apply all. Okay, so next there's thickness which I don't really care about. There's the resistance post trip. There's, you know, the resistance, the current trip you can see there's, it's usually about two times whatever the hold is. And then current max is like how much you could force through it before it gets damaged. Time to trip is, you know, how long that the high current before it actually trips. Most of these are about, you'll see they're all pretty much about 0.1 to 0.3 seconds. They're not instantaneous, but they're also not super slow. Just make sure that it won't damage your board. Okay, and next up, and then of course if you need overvoltage protection, this doesn't do overvoltage protection, this does over current protection. If you need overvoltage, there are different input filter chips that you can do that, you know, they're safe for a very wide range of input voltages or negative voltages and they won't let current through unless it's like the right level. And sometimes they also have current limiting as well. So this is good for USB where you're never gonna have something over five volts coming to USB. So you don't have to worry about protecting against overvoltage is just over currents. All right, so next up, let's look. So yeah, so you've got 750 milliamps. We've got 500, we've got one amp. Really, it's up to you. I think I'm gonna go with the 500 milliamps. It's a safe amount, but that's also again the standard. So having this be compatible with the Pro Micro, if it's doing 500 hold, I should do 500 hold. So when you do that, there's about seven options remaining. So there's a couple of, what's really nice is yeah, these are generic so you can get them from Borns and from Littlefuse and from Belfuse. As you can tell by the stock numbers, Belfuse is super popular. You know, there's 135,000 of these in stock right now. This is a nice rendering. And you know, it says 20 weekly time, but there's 135,000 in stock. So like we're good to go. And these are only about 10 cents a piece. So I didn't want to pick up these. They're good, but then again, don't worry about it. There's always uses available in that package from other suppliers. So you know, if you're worried about like shortages or something, just make sure you have the part numbers written down for all the alternatives. But this one seems like it's gonna be fine for quite a while. That's the great search. So question that was in the chat. I guess this is someone asking an opinion. New USB-C up to 48 volts. Well, that requires power delivery, which we're not gonna do on this device at all. Not gonna do that. Yeah, folks want to tear down the calculator. Not gonna do that. Not tonight. Not tonight. But I am gonna do, if you've stuck around this long, you get a treat. So here's the treat. In the chats, just tell me which one you like better. So we have an E and Trinkie that we're doing. And each Trinkie has its own little character. And so the obvious thing was like, well, it's E-ing, squid, octopus and everything. So we did that. This is the E-ing Trinkie character. But we don't have a panda. Pandas are black and white. And if they get in a fight, maybe they like to get bloodied or something like that. But here's the E-ing Trinkie panda. So we're gonna choose one of these. I mean, I guess it could morph into one and change back into it. But I don't know which one we're gonna do yet. But this is how it is. Maybe I'll put it up for vote or something like that. But I like both, but I don't know. Yeah. Panda or octopus or squid. So those are the two. Those are the two. And again, we're gonna have limited edition Trinkies and stuff like that. We're calling them NFTs, not forever Trinkies that are physical hardware. But anyways, so yeah, a couple of votes for panda. I think folks are saying panda. Panda, panda, panda, panda, panda. Folks are like a panda, yeah. All right, so so far. So far panda. In our focus group of 20. Yeah, you're right. There is red pandas too. So this one. Well, we have red mono, we have black, white and red E-inks. Squid. All right. This is catching up. Uh-oh, squids. Squids and octopus. Like, oh, now it's, now it's. That's neck and neck. Oh, now there's the. Squid. Yeah. All right, so that's the show tonight. Okay. All right, thanks everybody. We'll be this one or this one or both. We don't know which. Maybe one will eat the other. I don't know. Call them already. Okay. So we'll see everybody during the week. Thank you so much. That is your Descalade data for this week. Thanks everybody. Bye bye. Have a great week.