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 »

SmartParallel: n steps back, n+1 steps forward

The principle of ‘one step at a time’ is very sound. The more changes you make at once, the more places there are for bugs to hide. And that’s why this project has been progressing slowly – or not at all – just lately. Finally, though, I feel like it might be back on track. A quick recap: SmartParallel is… Read more »

Homebrew 6502: a new way to start

My Zolatron 64 homebrew 6502 computer project has stalled of late. But it is high on the list of things to restart once I get current projects out of the way. And a recent development has inspired me to look at it again. If you’ve been here before, you’ll know that my plan was to first build a kit –… Read more »

ESP8266 IoT room thermometer – part 4: the code

In response to a flood of requests – well, okay, one – I’ve posted the code for this project on GitHub. But don’t expect to be able to run it. That’s the thing about a maker project – you can create it to be used by anyone who cares to download your designs and code; or you can optimise it… Read more »

SmartParallel: serial shifter issues

I was pretty pleased with my serial level shifting board – right up to the point where I tried to use it. The tl;dr version of this post is that the board works, but not well enough. It has severe limitations that, I think, make it useless for the intended purpose. Let me explain… Voltage levels The purpose of the… Read more »

Fun with chips: #1 MC1441 bit rate generator

I’m easily pleased. Leave me alone with a breadboard, multimeter, oscilloscope and a previously unencountered IC, and I can amuse myself for hours. Well, minutes anyway. It’s fun to fire up a chip and watch it do its stuff. And even more fun if it’s an old chip. But before we get to the IC itself, let’s fill in some… Read more »

SmartParallel: laying out the PCB

We’ve been here before, but now it feels like we’re finally getting somewhere. The long-running saga that is my SmartParallel serial-to-parallel dot matrix printer interface is nearing completion. Well, maybe. Having solved (I think) the back-powering problem, and with a prototype that I believe actually works, I’ve decided to call Rev 2.0 of the design schematic the final version. All… Read more »