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VFD Display for the TI83+ Calculator

This project builds upon the PIC/TI83+ interface developed by ThomasHenry (see Nuts & Volts August 2013 A Mathematics Engine for Microcontrollers). Acknowledgment, appreciation, and kudos to him for writing the TI-library for Great Cow Basic that made this project possible.

When I recently re-discovered that article, I imagined re-creating the only calculator that was available on campus when I was a Freshman in college. That calculator was in the basement of the Chemistry building, and students had to wait in line to get their 10 minutes on the beast, which displayed results on several large nixie tubes. My version uses VFDs, is much smaller, but still is reminiscent of that unit. In short, this project will display calculator values or results on both an LCD and 11 VFD tubes.

The main components are:

The TI83+ and LCD (2 x 16)
PIC 16F88 – interfaces with the calculator, sends serial data to the VFD driver (A6812SA)
A6812SAVFD driver/shift register
PIC 12F683 - configured as a boost converter to provide the voltage to VFD grids and segments
11 VFD tubes - IV-6 type Rectangular LED – to indicate negative result”

Link to article