Welcome back to The Factory! This week, all the schmick looking black boards we've been working on finally have a name - it's Makerverse! We'll also talk about a 5V and 3V compatible SD card adapter and a power timer to take your projects off the bench and into the wild on battery power. Let's get started.
First up, we announced the brand Makerverse last week. If you've been following the journey of the perfect protoboards on the factory but aren't subscribed to the Core Electronics newsletter, Makerverse is the brand that we are releasing these Maker Essential products under. If you want to learn more about that, you can head over to the link in the description to see the protoboards on the Core Electronics website.
That also means I get to stop being coy with my strategically placed pieces of gaffer tape over the brand on all these prototypes. So now I can just show you in the flesh the Makerverse SD card module - that'll be our first prototype for the day.
We started working on an SD card module because data logging projects are so popular in the Maker community, and we just had to be a part of that with this SD card adapter. This is a breadboard compatible adapter, and it's actually one of the few modules that we are considering making with the header pins already fitted. That's because these kinds of projects often find their way into breadboard development, where you just want to experiment with an SD card on the breadboard using, say, an Arduino or a Raspberry Pi Pico.
In a lot of other projects, the headers are kind of optional, like say PiicoDev where you've already got a guaranteed way to connect to the device. We've gone for an SMD only approach for this adapter. So this is basically all the components are on one side of the board and we keep the other side completely bare and that way we can send it through our production line and just place all the parts on one side.
Requirements for a project like this is that it must be compatible with 5V or 3.3V operation. Even though most modern development platforms the operating voltage is coming down to say 3.3V, something like this you've just got to make it compatible with like the classic Arduino Uno experience and so that means that you need to put in a voltage regulator because you need to be able to power the thing from 5V and also a 5V tolerant buffer.
Let's take a look at the circuit. Here we have the SD card module schematic and we'll work backwards from the SD card connector. The chip select, MOSI and clock lines are all buffered through from the upstream micro controller through a 7.4 LVC125 which is essentially just a buffer that happens to have 5V tolerant inputs.
So even though this device will be powered by the onboard 3.3V system, those 5V tolerant inputs means that it will just pass a 3.3V signal or it will shift down a 5V signal from say an Arduino Uno at Mega 328.
So that means depending on the system voltage that you're using you'll either power it direct from a 3.3V micro controller through the 3.3V pin or if you're using a 5V device you'll power it through the 5V pin and that will be regulated by an onboard AMS1117.
The AMS1117 is a pretty jelly bean voltage regulator but we've opted for the slightly smaller package, the SOT223 package just so we can squeeze this board a little bit smaller.
Otherwise that's really it, you've just got some filtering capacitance, a switchable onboard LED so you can enable or disable that power LED if you wish, and just"A few resistors are used to stop the buffer from oscillating. When you mount it to your breadboard or circuit, you will only see the rear side of the PCB with some nice artwork on it. So, why bother with the logic level shifting chip when you could just use a voltage divider to shift the signals down? However, if you were to voltage divide down your 3V signals, you would come in just under the minimum high level that is acceptable for most devices.
Another consideration is that we wanted this device to run at a generous speed, and we have successfully tested it at 25MHz without any issues. You may have noticed that the MISO line, which is the data output line of the SD card, goes straight to the connector without any buffering. This may seem strange since it is a 3.3V signal going to an Arduino Uno, which is typically good for 5V. However, according to the datasheet, the input high voltage acceptable for the ATMEGA328 is 0.6VCC, which is 3V in this case. So, we don't need to buffer or modify the signal coming out of the SD card, only protect the SD card itself, which must run at 3.3V.
Moving on to our next prototype, we have the MAKERVERSE Power Timer. This device is designed to make it easier to take your project off the bench and make it battery powered. Battery powered projects can be challenging, as they require power management, shutting down peripherals, and having a power-efficient circuit design. These factors can be a barrier to making your project battery powered and taking it into the wild. The MAKERVERSE Power Timer aims to address these challenges and simplify the process.Bridge the gap. What this does is it powers your project, say from a battery or just from voltage that you supply at one of the pins and periodically, depending on the time you set, it will apply power to your project.
Your project powers up, it does whatever it needs to do, maybe it reads some sensors and logs to an SD card and then when it's finished you send a done signal back to this device, so just a digital high signal to the done pin. The power timer will then completely cut power to the project until the timer elapses again for the next cycle.
You can configure this to power your project from anywhere between once every 15 seconds to 2 hours just using these dip switches. We have this row of dip switches here and the idea is that you configure the time that you want to set using the position of these switches where you can go from just having switch A on, which is a 15 second cycle, all the way up to 2 hours if all the switches are off.
There's even a provision for a user resistor to go in there, so if you make some custom resistor out of a bunch of resistors from your drawer, you can put it in there and get a custom time that you want.
So here's a graph of the times that are possible. On the bottom row is our design and the X's indicate time in seconds for just one of the switches. So this leftmost X is the first switch and that would be for 15 seconds all the way up to an hour and 2 hours. What we were going for here was to try to get as useful a spread of times as possible.
So we have our first switch here at 15 seconds, our second switch here at 1 minute, 5 minutes, 20 minutes, 1 hour and 2 hours. Like real natural kind of sampling intervals. And then these red dots that are appearing are what can be achieved by using a combination of switches. So if you turn on 2 switches, you'll get some time that is less than both of them and that just gives you a few more options.
We based this design off a design by Sparkfun that uses the same timing IC, the TPL5110. And we've graphed their times as well because we noticed that there was a bit of a gap that we could potentially fill just by changing the design of the circuit slightly.
I won't get too, too into the weeds with how we chose these values. It's really just applying the formulas in the data sheet, but it really just comes down to choosing the unique values for these resistors R1 through R7 to give a nice breakdown of what times are available.
Another feature we included on board was to include a reverse polarity protection shocky diode that can also be bridged out because we know that if you somehow back power this timer, say if you're powering an Arduino UNO and power comes back through because you've plugged the thing into USB, that can be really bad for the TPL5110. So we included this reverse polarity protect diode. But if you know what you're doing and you just don't want to suffer that small drop in power that you'll get across the diode, it can be bridged out.
And of course in power projects, every drop, every joule counts. So we've included a jumper to disable the active LED as well.
This device is kind of amazing. It operates down like somewhere in the nano amps when it's standing by, just waiting for that timer to elapse. So these resistors aren't actually in circuit all the time. So it appears the moment you power this chip up, it samples what the time ought to be. And then basically it doesn't look at those resistors again until you remove power.Apply it again. And that might be how it can keep its power consumption so low.
TPL5110, needless to say, very impressive device, super low-power consumption. And so yeah, hopefully that just makes it a little bit easier to take your projects off the bench and into the wild.
And final order of business for the day, a nearly, a nearly perfect protoboard. We're working on yet another Makerverse protoboard, this time compatible with SOIC or other SMD packages.
So the point here is that it's just like any other perfboard. It has that standard 100 thou grid of 1mm holes so you can put your dip packages in, you know, put in pin headers, whatever. But here's the thing, the pads are much smaller and in between we can fit little islands so that if you were to put, say, an SOIC onto this, you would have a pad for every single pin.
And this is great if you want to like break out from through-hole parts and start experimenting with some SMD parts or maybe, you know, for a lot of good parts that are only available in surface-mounted technology, you know, like high-quality operational amplifiers, high-speed digital circuits, a lot of these things are only available surface-mounted.
And so we're kind of wrapping up the line with this one. We're doing this one last because it's a bit more in the esoteric space, but man, I think you can get some really cool stuff done with it.
We took a run at getting this board done using hot air-leveled solder finish and the user experience was pretty so-so. You can see here where we lifted one of the very small pads and that strange-looking geometry, we've seen that before in boards like this and it appears to be so that you can easily create solder bridges, but at least in this case, it's actuallyFar too easy to create solder bridges between these pads, quite frustrating to use at this point. So we've got a design revision in the works where we will have mask on the front, just to help with the solder bridging so that you can make them when you want to and avoid them when you don't.
But we've also simplified the geometry a fair bit because these like kind of arrowhead interlocking chevrons, it just isn't really working out and we think that maybe with a simpler geometry, it'll actually be easier to look at the board and understand what's going on. So we're re-spinning the board with any gold and we'll give it a test drive.
That's just the front side of the board. On the back side, we have a continuous plane that's isolated from all the pads. That means that you can set this to be your ground plane and then all you have to do is solder from that plane onto one of the pads to make a ground connection and this is where a board like this will really come into its own for high speed or high frequency designs.
By having like a good ground plane on the back, you know, you might be able to squeeze a circuit on here that can handle like 50, maybe even 100 MHz signals, whereas you know on a breadboard, you really capped it like a couple of MHz before it's just the capacitance is just too much. On a more classic style of perfboard like this one where you just have square pads, you know that'll still be good for a few megahertz, like maybe up to 10 megahertz, but it's really that ground plane that's going to make all the difference.
And yeah, you really just don't know until you try to build something on the thing. So we've got that design revision coming in. We're looking forward to, I don't know, making sure!
Some kind of oscillator on it and getting the scope out. In any case, that's all I have for you today. Let us know if there's anything you'd like to see in our range of Maker Essential hardware that is Makerverse. And until next time, thanks for watching!
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