Tag Archives: prototype

SmartParallel: stripboard prototype – now with blinkenlights

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 »

SmartParallel: stripboard prototype

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 »

SmartParallel: breadboard prototype

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 »

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 »