Welcome back to the factory. This week the RTC modules are in and ready for discharge testing. We've even got the production jig that we can start prototyping as well and we're working on some new addressable LED projects. Let's get started.

Last week we introduced you to a RTC module that we've been working on. I'm happy to say that the prototype PCBs have arrived and we've assembled a few and the negative labels just look fantastic. The KeyBuzzard plugin that we're using to make these labels has made for some really attractive square labels with the text in like negative or in relief. Very pleased with how that looks with the white silk on black.

We've actually assembled a few of these, charged up the supercapacitors and we're letting them run for a couple of days, measuring the voltage each day so we can get a good idea of what kind of life we can expect out of these. Even though the onboard RTC has a really really low current consumption it's basically the same as the self-discharge of the capacitor so we just don't know exactly how far that tail of lifespan is going to go for this capacitor. So we have to test it empirically.

Something that's quite interesting to note with this device is that the charge current is actually user settable through I squared C. So in the setup for this device you actually select basically the inline series resistor that is going to charge the RTC which brings us to the test jig.

While we were getting that prototype sent off we also spun up a simple test jig. I discussed last time because this test might take more than just a handful of seconds, it might be up to 15 or 20-30 seconds for a test, we decided to make a bit of a batch tester so that we can load a module into one position.And the test begins for that module. We can load up the next one and by the time we've loaded up all four positions, the first test ought to have finished, and we can just keep rolling through that circular buffer of tests as it were.

So there's quite a few things to test with a board like this. Of course, you have to test that you can talk to the thing over I²C, but we also need to test that we can power it up, charge the supercapacitor. So we need to measure the voltage on the supercapacitor. We can remove power from the clock to ensure that the battery backup is working, and then we can apply power again so we read the time again after a power cycle to make sure that the battery backup was keeping the clock ticking during power cycles.

So here's a block diagram of how we intend this test jig to work. We've got a Raspberry Pi Pico driving the show, and its I²C data and clock lines each go to a four to one MUX that is then broken out to each of the four RTCs under test so we can basically by switching the MUX determine which RTC is connected to the I²C bus of the Pico. We do the same with one of the analog channels so that we can measure the voltage on that supercapacitor and just make sure that it's charging correctly.

Not pictured here is that every RTC is actually powered by one of the Raspberry Pi Pico's GPIO so we can independently turn them on and off to cause that power cycle.

Something that you RTC aficionados out there might appreciate that this real-time clock chip, the RV3028, actually has two independent timing registers. So it has the one that we're all familiar with, which is like the day, month, year, hour, minute, second like the calendar registers, but it also has an independent Unix.Time register, which is just that long integer that ticks up once per second. So you could hypothetically have a different time set to each of these clocks and have them running independently. I'm not quite sure what you would use that for, but hey, you've got options.

As a side note, something we've been doing with our test jigs now is to self-document the layout of the mounting holes. So that when it comes time to mount one of these onto a base or some kind of platform, build some jigging around it, we have all the dimensions of the mounting pattern just available on the board.

This line of blackboards that we're making is intended to be the really maker essential kind of hardware. The kind of hardware that you just want to get your hands on and experiment with. Well, the kind of hardware that you know invariably finds its way into projects. So, you know, there are a lot of clock projects out there. So we thought an RTC module would be a great place to start. But what other maker essential hardware would you like to see in a line that looks like this? Let us know.

In other design news, we've been working on some new Glowbit products. We haven't really talked about Glowbit for a little while on the factory, but here we have the makings of an 8x8 LED matrix. Now, if you're not familiar with Globit, that's our name for WS2812 version 5 LEDs. The version 5 is quite important because that means that this addressable LED works with a 3 volt supply quite reliably. And it also works with 3 volt logic on a 5 volt supply. So you're guaranteed to be able to drive it to maximum brightness using 5 volts while still only using 3 volt logic. No logic level conversion needed. And very importantly, no external components.So, it keeps your designs quite clean. You don't need any protection resistors and there's no decoupling caps. With the older technology, each one of these LEDs would have needed a decoupling capacitor. And, you know, while that's not much of a visual impact, it's not nothing. So we're quite happy to be able to offer LED matrices that are just clean, just LEDs.

I'll turn off ray tracing so we can take a walk around this board. The front is, you know, the front is exactly what you'd expect, a regular matrix of LEDs. There's a lot of discussion around how we space these so that we can fit in connections and mounting options. You often see these matrices with screw holes milled into them, but actually, the LEDs are so close together that if you actually put a screw into those holes, you would probably cover an LED or at least the screw would touch it, contact it, maybe put pressure on it and maybe break it off. Because this board is only about 60 millimetres by 60 millimeters, at the moment we decided to just keep the mounting options as regular pin headers because they can fit neatly in between the LEDs.

The board is not that big, so they should provide ample mounting support. And importantly, everything's on a 0.1 inch grid, so you could tessellate these matrices together, you could tile them essentially, and either connect them with a pin header, just a two-pin pin header with a jumper, or you could solder them to some standard perf board and it would keep the spacing so that they tile very cleanly. So we're very excited to see what the artists and creatives out there can do with an affordable and tileable 8x8 RGB LED matrix.

The Gerbers have been submitted. I think we'll be assembling a prototype sometime next week. We're also going to roundThat out with a similarly tileable 4x4 matrix that is probably just suitable for just mucking around with on a breadboard or making of course a smaller display and a 1x8 stick so here we just have a single header for power ground data in and data out but as with most LED sticks we've also included the surface mount pads on the back so if you wanted to you could tile these end-to-end to make say a bar graph.

In any case that's all I have for you today super excited to receive these Glowbit prototypes and assemble them make something fun out of them and by this time next week we should have some good data to share with you for the RTC discharge test.

Until next time, catch you later.