Feels like 2001: a fresh Windows XP install

Ah, there’s nothing quite like the feel of a fresh, crisp OS install. It’s just that the OS I’ve just installed is Windows XP. Now that makes no sense… Or does it? As I’m now playing with my BBC Master again, I felt the need for a Windows machine to have alongside it. There’s a bunch of utilities that run… Read more »

Flowchart your way to success

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Does anyone still use flowcharts for programming? What with today’s complex development frameworks it seems unlikely that anyone’s stopping to draw diagrams on paper. But maybe if they did we’d have fewer security vulnerabilities – just sayin’. My addiction to computers, in the early 1980s, was driven in part by ‘30 Hour Basic‘, an introduction not just to the language… Read more »

ESP8266 IoT room thermometer – part 3

The best projects are the ones you finish. And as projects go, this IoT room thermometer – and, for good measure, clock – was one of the easier ones. To recap, I wanted a thermometer in my office to measure the temperature and compare that with how I’m doing, at any given time, in terms of hand pain. I have… Read more »

SMD soldering coda: KiCad, PCBs and pad sizes

In many ways this is Part 5 of my four-part series on SMD soldering because it addresses problems I had with reflow soldering and TSSOP ICs. I used two TSSOP chips – the TXB0104 and TXB0108 level shifters. Both have pin sizes of 0.3mm and a pin pitch – the distance from the centre of one pin to the centre… Read more »

DottyMatrix software stack: PHP & Python messaging

On the Raspberry Pi that I’m using to control my DottyMatrix serial-to-parallel Centronics printer interface there are two main software components – a web-based PHP/JavaScript front-end UI and a back-end server programmed in Python. So these need to talk to each other. Here’s the overall architecture of the solution: The matrixSvr.py program is intended to run permanently on the RPi… Read more »

DottyMatrix software stack: the front end

It’s one thing building an interface – it’s quite another working out how to use it. My DottyMatrix serial-to-parallel device is designed to drive my venerable old Epson MX-80 F/T III dot matrix printer (although it should work with any printer using a Centronics parallel interface). So far, I’ve mostly spoken to it using a terminal, sending text directly from… Read more »

The Master is back!

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My BBC Master micro is alive again, thanks to a generous donation. So what was wrong with it before? Buggered if I know. The Beeb suddenly developed a fault a couple of years ago. On powering on, it would show the OS greeting and sometimes the disk filing system greeting but would then hang. I tried a few things but,… Read more »

DottyMatrix: a simple solution?

The DottyMatrix project began when I thought, ‘It would be nice to make use of my old Epson MX-80 F/T III dot matrix printer’. The problem was talking to it. But then I thought, ‘It’s just parallel printer interface. I’ll make a microcontroller-based device to act as an interface. How hard can that be?’. The answer, it turns out, is… Read more »

Lesson learned: check the power

The PCBs arrived from the fab house and I was impatient to try them out. They’re nothing clever – just a way of saving a bit of wiring for my ESP8266-based IoT room thermometer. Aside from headers, there are just four components (not including the pullup resistor I don’t need anymore because I made a mistake). I hand-soldered on the… Read more »

Adventures in SMD soldering – part 3: in the oven

If you’re working with solder paste, as I was in the last post, there’s an easier method of applying heat than blasting the PCB with a hot air gun. And that’s to put it in the oven. This is how most commercial soldering is done these days. But this reflow soldering is easy to do at a hobby level, too…. Read more »

Adventures in SMD soldering – part 2: hot air

While hand soldering SMD/SMT components on to a PCB is certainly feasible, I figured there had to be a better way. That’s when I heard about using hot air rework stations to do the job. The concept is simple: apply solder paste to the pads; place the components on the paste; apply hot air. The paste melts and effectively sucks… Read more »

Adventures in SMD soldering – part 1: by hand

A little while back, I wrote about my SMD soldering setup. It was very much an overview and mostly about the kit. Now, I know many beginners, like me, are intimidated by soldering surface-mount parts. They’re so small and the pins on ICs are so close together. But there are good reasons for getting over the fear. Many parts are… Read more »

DottyMatrix: A simple acknowledgement

Although it was gratifying (and surprising) that my DottyMatrix serial-to-parallel interface worked as soon as I plugged it into an actual printer, there was one nagging flaw. And that was a lack of acknowledgement. The /ACK signal in the Centronics interface was often sadly neglected, if not ignored completely. But in theory, the sequence for printing a character goes like… Read more »