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 »
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 »
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 »
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 »
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 »
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 »
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 »
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 »
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 »
Here and there on the web I’ve noticed a bunch of people relating stories about their first experiences with computers, so I thought I’d join in.
The Centronics interface seemed such an intrinsic part of a computer’s architecture that, to those of us whose computing coming-of-age was in the 1970s or 1980s, it seemed unimaginable that it would all but disappear. Who knew that serial interfaces would one day reign supreme? There’s something still very satisfying about hooking up a parallel connection, with fat cables and… Read more »
Okay, so I’ve already fessed up to some errors I made with my first-ever PCB. Now I’ve discovered another, and it’s a doozy. It’s also a valuable lesson. I’m waiting for a few bits of kit in order to do surface mount soldering. I’ll be writing more about this when it’s all installed (but as a teaser, it’s a hot… Read more »
Things can get a little confusing with the 6502 microprocessor’s clocks. The datasheet details three clock pins which, for the current version of the chip are PHI2, PHI2O and PHI1O. And with older versions of the 6502 you’ll see PHI1 instead of PHI2. As I detailed in a previous post, the situation is actually simpler that it first seems. It… Read more »
The Zolatron 64 6502-based homebrew computer has a 16-bit address bus and I want to be able to interact with it manually. How do we do that? The answer is a front panel with switches and lights, as outlined in the last post. But it’s going to be a bit more complicated than just wiring each line of the bus… Read more »
Any self-respecting retro-style homebrew computer needs two things – switches and blinkenlights. Otherwise, why bother? I haven’t got a working computer yet but already I’m thinking about a front panel for it. This will be inspired, to some extent, by the Altair 8800 and also by the PDP-8, both of which I have in the form of modern replica kits…. Read more »