Just a quick update to about the SD Bootloader I designed a few posts ago. Well, the PCBs have arrived and last week I took a soldering iron to one of them and gave it a quick test
One side of the board is effectively an Arduino, so without plugging it in to the RC2014, I connected up an FTDI lead and uploaded the Arduino Blink sketch. A quick check with a multimeter and one of the pins was altenating between 5v and 0v. So far, all good! (more…)
Despite a late start today, things have gone well so I actually feel like I’m ahead of the game right now. Certainly not finished, but with most of the major hurdles now behind me, the only thing left is writing a bit of Z80 assembler code. And even that is starting to look manageable.
So, exactly 3 weeks after they were ordered, the PCBs from OSHPark arrived today. It’s just as well, as I was running low on things to do without them, and with just 6 days left of the Retro Challenge I would have struggled to finish in time.
Well, that’s my weekend planned out for me now! (more…)
The mounting of the LED matrix has probably caused me the biggest turmoil so far on the Retro Challenge. First, I was going to design a custom PCB for them, but I missed the window of opportunity to get it manufactured at a reasonable price. So, for simplicity, I decided to use breadboard until I realised this wasn’t simple with that amount of wires. So, I went back to PCB design preparing to take the financial hit. However, it proved impossible to get the tracks to fit, so this idea went in the bin again. Back to breadboard, I bought a load of jumper cables, and started expanding on what I started earlier. For the driver chips it was ok. For the matrices themselves though, I came across a show stopper; The width of it is so wide that in the breadboard there are 2 free tie points on one side but just 1 on the other. Getting a data bus down all of them was not going to be possible :-(
So, I had a rummage through some vintage Veroboard and found a Euro-card sized board with chip layout tracks. It would only fit 5 modules side by side, but I was prepared to make that sacrifice. I also had some 40 pin female sockets, so that made life even easier!
We’re at the halfway mark of the Retro Challenge, and there’s a slight lull in activity, so this seems like a good chance to catch up on what’s been done so far, and what’s still to come.
Firstly, a quick review of the challenge I set myself; write my name in LED lights. These must, however, be controlled by a Z80 computer, which I’ve got to design and build myself, and written in assembly language which I need to learn.
Well, the start of the challenge saw me dive headlong in to KiCad, learning some of the intricacies of printed circuit board layout. I’d used KiCad for a couple of little projects before, but certainly wouldn’t have described myself as competent. I’m still not a master of it, but I’m a lot more familiar with it than I was.
I split my breadboard based Z80 down in to several modules, each of which will plug in to a Veroboard backplane. 6 of these have been designed and sent off for manufacture which will give me a basic Z80 computer that I can use via a terminal emulator. The boards are;
I knew there would be some stumbling blocks with this Retro Challenge, but, hey, it wouldn’t be a challenge if everything was just nice and simple. However, I seem to be beset by little stupid technical issues that aren’t necessarily retro in nature.
However, the fact that you’re reading this does at least mean that my blog is working again! I ran some updates last week, and it caused some issues with a plugin meaning I had no way of adding, editing or modifying any posts. I’ve now got that tracked down to the Poll plugin and disabled it. So, yay, I’m back!
So, part of this challenge is to use LEDs, and the little 8×8 matrix modules I found seem ideal. I had initially intended to design a PCB to mount a bunch of these on, but due to time constraints, it was looking very unlikely I’d get them designed, ordered, manufactured and delivered by the end of the month, let alone time for testing. So I decided to go Old Skool, and do this part on a breadboard. Well, 2 breadboards, as they each need a driver chip. Although, it’s actually 3 breadboards, as 2 aren’t quite big enough. Not to mention the other breadboard with the supporting circuitry on. I made a start on this last night;
So, after a flurry of activity, blog posts and updates at the start of the month, things have got a bit quiet.
That’s not to say I haven’t been doing anything. I have. Lots. But nothing really specific or bloggable.
Until the batch of PCBs arrive, I am kind of in limbo land. However, I’ve been looking in to the LED matrix boards a bit more, and working out how I’m going to connect them up (short answer – use breadboards to complete the challenge, but get PCBs made up for long term mounting.).
As the breadboard Z80 runs Microsoft Basic, I have been using that to test out a few bits in terms of orientation of the matrices and the best way to drive them.