Breadboard Bits - Pic16F84, V1.5

Introduction

After having built a proper PIC programmer, the original microcontroller development suite, which used a programmer breadboarded alongside the chip and an external parallel IO box, seemed obsolescant. So I decided to build a new development platform.

Old Second-Generation Development Board

The board as it stood when I rediscovered it. An HD44780-based LCD module was dangling off the board by a pair of power leads, but as far as I know, I did not actually init the LCD back then.
Several unusual things went into this board. For one thing, the presense of fixed binding posts on a custom aluminum bracket and the custom made ICSP (In Circuit Serial Programming) cable demonstrate the equipment and capabilities I had available at the time. Incidentally, the loss of this ICSP cable was part of what caused the complete redesign and redevelopment of my PIC programming systems for V2.

I actually have very little detail on what this board was used for. My recordkeeping at the time was not as polished as it is now, and so the exact nature of the experiments done on it are a bit mysterious.

The interesting part here is the rather nontrivial analog circuit on the bottom left panel. This board was designed a sufficient number of years ago that the design of that circuit would have been out of my realm of experience. Not only that, it lacks the character that my own analog circuits have: it has a PNP transistor and a JFET, while the vast majority of my circuits are constructed entirely of NPN transistors. So I conclude that I was working partly from schematics, rather than from original designs.

It would appear, especially given the 7404 inverter on the right panel and the presense of an LCD module, that this board was a prototype for an LC meter. I do recall at the time that I had an interest in such things, before learning to read the capacitor code and to design inductors and how to measure either using an oscilloscope.

Incidentally, I began working on a frequency counter based on the much more powerful (yet cheaper) PIC18F1320 much later. A lot of design elements are shared between the two systems, and in many ways, this board was the trial run for it.