Okay, so the next stage of the stripboard prototype for the SmartParallel serial to parallel printer interface went well. Mostly. As planned, I added a bar LED block with eight segments to show the state of the data lines, along with power-limiting resistors in the form of a resistor array. I also added four LEDs. Three are driven via a… Read more »
Things went from bad to worse with the breadboard prototype of the SmartParallel serial to parallel printer interface. All was fine for a while. Lines of text sent from my Mac via an FTDI cable were duly printed on the Epson MX-80 F/T III dot matrix printer. But then, every now and again, the printer would randomly reset. After a… Read more »
It’s never a good idea to let signals float around in the no-man’s land between the high state and the low state. This is why we so often use pullup and pulldown resistors. You set the line to a known, definite state by default and then switch it as necessary. Some uses of pullup and pulldown resistors are obvious. Some… Read more »
Ah well, another valuable lesson learned. The PCBs for my homemade joystick, designed to work with the BBC Micro and Master, should have been very simple. They are very simple. And yet I still managed to screw up. The PCBs for both the main adapter, which plugs directly into the computer, and the connector for the joystick arrived the same… Read more »
A major reason for doing breadboard prototypes is to learn what mistakes you’ve made in your circuit design. Of course, it’s also a way to introduce brand new errors. Or both. Before committing to fabricating PCBs, I wanted to check out whether my design for the SmartParallel dot matrix printer interface would even work. My confidence was reasonably high because,… Read more »
Okay, I lied. Having ordered the PCBs for my Centronics breakout board, and also having ordered a couple of DB25 breakout boards via Ebay, I settled in for the long wait I knew would follow. I said in an earlier post that I was getting used to these two to three-week delivery times for stuff coming from China. The truth… Read more »
Jumper cables with DuPont headers are an essential part of your toolkit. Any dabbler in electronics will have drawers of the damn things – and probably not a few wandering randomly around the workbench. But when the time comes to buy more (where do they go?) there’s always a dilemma. Do you need male-male, female-female or female-male? And how many of… Read more »
Creating a full breadboard version of the SmartParallel board is turning out not to be a five-minute affair. It has to be done meticulously and methodically if it is to have any value as a prototype. Fitting it all on to a single breadboard is proving challenging too. And that got me thinking. What about replicating at least part of… Read more »
Hmm, yes, clearly it wasn’t going to be as easy as all that. While creating the PCB layout for the SmartParallel serial to parallel printer interface, I shuffled a few of the pin assignments on the Atmel ATMEGA328PB microcontroller. The reason was simply to make routing a tad easier. But I had a nagging feeling that this might cause a… Read more »
Not every device speaks the same voltage. In designing the SmartParallel serial-to-parallel printer adapter, I chose to use 5V as the VCC supply throughout the board. But I was constantly aware that some of the devices that might talk to the board – such as the Raspberry Pi – use 3.3V for their I/O. What to do? There’s only a… Read more »
Well that wasn’t easy. Finally, the SmartParallel TTL serial to parallel printer interface has a complete PCB layout. And I learned a few lessons along the way. The most important of these, perhaps, is that when assigning signals to the pins of a microcontroller during the schematic drawing part of the project, don’t rely on whimsy or the luck of… Read more »
In my series on ‘building’ a PC, I mentioned that a motivating factor was to have a games platform. I think I mentioned Elite: Dangerous and Kerbal Space Program. The truth, though, is that I wanted to play with flight simulators. I first took up Microsoft’s Flight Simulator when it was version 2.0 and running on DOS. I stuck with it through to… Read more »