TI-83 as data logger?

[NiHaoMike]

Has anyone thought about using a TI-83 as a data logger for hypermiling? It's cheaper than a Scangauge (especially if it's used!), is relatively easy to program, and has a very complete library of math functions just to start. And of course, you can connect it to your PC to save data for long term logging and it's also a very good calculator.

One implementation could be use one I/O line for the speedometer input and the other to monitor the fuel injection. A very simple circuit consisting of two resistors and two zener diodes will be all that's needed to interface it. As a bonus, it will work in cars too old for a Scangauge.

A more complex implementation could be to use an interface chip to connect it to the debug connector.

If a TI-84 or TI-89 is used instead (those calculators have clock chips), the average speed can also be logged. (Of course, that probably wouldn't be worth the extra cost.)

[John L.]

That's a novel idea, but remember that the TI I/O port is a serial line, so your best bet would be to have an A/D converter and then convert the digital signals into serial comms. You'd have to know how to use the serial comms in the program you write but the info is definitely out there to do it. You know loggers for PC are really cheap though right?

[wikityler]

You'd need an MCU to do the signal<>serial conversion, so you mind as well just add rs-232 and some flash, and eliminate the calculator.

[NiHaoMike]

The link port in the TIs also work as a GPIO, so just voltage level translation is needed if sensing the injector and speedometer signals. Particularly interesting could be if a cheap wireless audio device is modified to send the signals wirelessly to the calculator. Then no wiring needs to be routed into the cab to install it.