Monthly Archives: May 2018

DottyMatrix: Printing to an actual printer.

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 »

ESP8266 IoT room thermometer – part 2

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 »

ESP8266 IoT room thermometer – part 1

Impulsiveness is not always a good thing. So here’s a handy rule for you: first, prototype; then fabricate the PCBs. Doing it that way, things have a chance of going well. Reverse that order and … well, not so much. Not that it was a disaster. In fact I had prototyped this little project – mostly. But we’re getting ahead of ourselves…. Read more »

DottyMatrix: It’s alive!

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My old, beloved Epson MX-80 F/T III dot matrix printer is back in the land of the living. For now. As you can see from some of my earlier posts, I’m designing a serial-to-parallel interface with Centronics compatible DB25 connector so that I can print to my Epson from anything with a TTL serial port, such as a Raspberry Pi…. Read more »

DottyMatrix: ghost of the typewriter and the curse of the carriage return

In designing my DottyMatrix serial-to-parallel printer interface, I had to decide how it would handle the incoming data stream. The purpose of the DottyMatrix is to connect my venerable Epson MX-80 F/T III dot matrix printer to (probably) a Raspberry Pi so that I can print out text files, such as program listings. Obviously, it would be good if it… Read more »

SMD soldering setup – just add air

It was time to get serious about SMD soldering. And I have to say, I’m really pleased how well this has worked out so far. Now that I’m getting into, and hugely enjoying, PCB design and getting boards fabbed, I can’t escape tackling SMD (or SMT if you prefer) components. And this is a good thing. For a start, an… Read more »

DottyMatrix and Virtual Printer – together at last

It’s great when a plan comes together. Having independently played around with my DottyMatrix serial-to-parallel printer interface and the Virtual Printer (designed to simulate my still-dead Epson MX-80 F/T III dot matrix printer), it was time to hook them together. And it worked! On the left is the DottyMatrix using my prototyping board for the ATMEGA328PB microcontroller. Its serial port… Read more »

Virtual printer & more fun with AVR interrupts

In building my AVR ATMEGA328P-based ‘virtual parallel printer‘, there were two signals that required special treatment. So it was time to revisit interrupts. On a Centronics-style parallel port, the host machine sends an ‘init’ or reset signal to the printer to tell it to flush its buffers and set itself to the default state. It also sends a ‘strobe’ signal… Read more »

Building a virtual parallel printer

Here’s a tip for anyone building a device designed to interface with a parallel printer – you kind of need a parallel printer to test it on. That shouldn’t have been a problem. My DottyMatrix project – which will allow me to send data over a serial connection and have it printed on my Epson MX-80 F/T III dot matrix… Read more »

Making tools #2

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Some time ago, I wrote about how I’d hacked together a board to program and experiment with AVR ATMEGA328P microcontrollers. Well, now I’ve stepped things up a bit. Mk.II The key features of the old board were a ‘zero insertion force’ (ZIF) socket for the microcontroller chip and a 2×3 HE10 socket to take the ISP cable from my programmer… Read more »