While idly mulling over how one might create a control panel for an eight-bit microcomputer – something I plan to do for my (very) slowly progressing Zolatron 64 project – it occurred to me that there might be occasions when it would be useful to send a brief pulse. I didn’t have a specific use case in mind. In fact,… Read more »
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 »
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 »
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 »
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 »
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 »
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 »
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 »
Over the past three posts I’ve looked at three ways of soldering SMD/SMT components on to a PCB – by hand, reflow soldering with a hot air gun, and reflow soldering with an oven. Now it’s time to draw some conclusions.
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 »
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 »
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 »
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 »
It seems the repairs to my venerable Epson MX-80 F/T III dot matrix printer did actually work because it’s now printing again! What’s more, it’s printing via the prototype of my DottyMatrix serial to Centronics parallel interface. Time for a quick recap. The DottyMatrix is based around an AVR ATMEGA328PB microcontroller. It takes input on a TTL-level serial connection and… Read more »
Having cobbled together an ESP8266 microcontroller, temperature sensor and TFT LCD screen, the next step was to have the device talk to a server. There are two reasons for wanting to connect to a server: first, to get time and date updates; and second, to report the temperature and humidity so that the server can display them on an intranet… Read more »