Author Archives: Machina

Following Ben Eater’s 6502 project – parts 1-3

No, this is not a post about stalking. I’ve been toying with a design for a simple 6502-based homebrew computer for a while now. I’ve built a kit and am in the middle of laying out the schematic for the first board for my own design. So I was thrilled when Ben Eater, one of the best educators on YouTube,… Read more »

SmartParallel: troubleshooting with logic analyser and scope

Well, it does seem that the problem I’ve been having with the SmartParallel board is indeed that horror of horrors – the intermittent fault. Or perhaps something weirder. This is some kind of quantum device – it works only when being observed. Setting up a server The SmartParallel was working perfectly for a few days. Then I didn’t use it… Read more »

SmartParallel: tracking down a problem

Hmm… maybe I spoke too soon. No sooner had I congratulated myself on a completed project than a problem raised its ugly head. And it was one that required some tracking down. And so, as this blog is my lab notebook, I thought I’d share what happened, as I always find other people’s tales of troubleshooting to be illuminating. One… Read more »

SmartParallel: mission accomplished

It’s done. For now. After weeks of dithering, I finally got around to making up one of my SmartParallel serial-to-parallel printer interface PCBs. I chose to solder the components – mostly surface mount – by hand and that went easier than I expected. The only snag was that it didn’t work. Not right away, at least. And finding out where… Read more »

Building a photo digitiser

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Regular readers will know that, in real life, I’m a photographer. And I’ve been one for a long time, which means many of my images were shot on film. They’re not going much good just sitting in filing cabinets – I need digital copies, which is where this project comes in. But first, some caution is required: if you like… Read more »

Rat B@stard mk.1 – a rodent scarer

They’re back! It could be squirrels. Maybe mice. Possibly rats. But whatever they are, the bastards are making themselves at home in the engine compartment of the car again. We had this with the Citroen C5. Twice the twitchy-nosed little feckers chewed through the cables for the top-dead-centre sensor, leaving the car in a state where it would turn over… Read more »

6502 homebrew: display and keyboard problems

The Apatco 6502 breadboard computer kit I’ve been building is complete. The next stage was to make it more so. A word of warning, though. This story does not have a happy ending. Nonetheless, someone may find the attempt at debugging entertaining or instructional, so here it is. The kit is sold (or perhaps ‘was’ would be better, as it… Read more »

6502 homebrew: the software toolchain

Now that the Apatco kit is working – at least the basic version (having trouble with the keyboard and display upgrade) – it’s time to mess around with writing code for it. Many people swear by the now-abandoned CC65 as their compiler/assembler of choice for 6502 homebrew computers. But I’m going with Beebasm. Although inspired by and largely aimed at… Read more »

6502 homebrew: debugging the kit #2 [solved]

If in doubt, start again. That’s not a real saying, but it should be. As we saw in the last post, the Apatco 6502 breadboard computer was finally wired up but refusing to work. I’d fixed my faulty ROM code, buzzed out all the address and data lines to check they were connected correctly and determined that the reset circuit and… Read more »

6502 homebrew: debugging the kit #1

Okay, so it was time to deal with something that has been nagging at me for a while. I have this Apatco kit 6502 breadboard computer kit and never quite got around to finishing the basic setup. It takes a lot of wiring. I just got tired, put it in a box and shoved it in the projects cupboard. For… Read more »

Arduino: running hard to stand still

Don’t you hate it when something that was working stops? You can safely bet that it’s because, somewhere along the way, something has been ‘improved’. I needed to make a change to the code running on a couple of IoT room thermometers. These are built around the Adafruit Huzzah ESP8266 board (the non-Feather version). And they’ve been running flawlessly for months…. Read more »

IR remote control for the home – part 3

In the previous two posts, we set up an ESP32 development board with an IR receiver to read codes sent by a remote control. Now it’s time to add MQTT capability. I chose the PubSubClient library – available in the Arduino IDE library manager – because it claims compatibility with the ESP32. When I looked closer, it turns out that… Read more »

IR remote control for the home – part 2

In the first part, I outlined my plan to build an infrared receiver to act as a hub for IoT devices in the home. Here, we’ll take a closer look at house the receiver works. Here’s what is required for this initial stage of the project: An ESP32 development board. I’m using a DOIT device, which costs around $14. A… Read more »

IR remote control for the home – part 1

How many remote controllers do you have in the house? One for the TV, one for the DVR, one for the Blu Ray player… There are five remotes sitting on the coffee table in our living room. Plus another couple scattered around the house, controlling table lamps and other TVs. And do you know what? This post isn’t even about… Read more »

SmartParallel: Go code is go

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Success! The Go code I’d been struggling with is working, although it also required changes to the C++ code running on the ATMEGA328PB. Here’s a quick overview of how the process works. On the SmartParallel, the ATMEGA328PB code sits in a loop watching for incoming data on the serial port. It also monitors the state of the printer by frequently… Read more »