Graphic calculator as a spectrum analyzer

[Michael Vincent] turned his TI-84 Plus into a spectrum analyzer. By running some assembly code on the device the link port can be used as an I2C bus (something we’ll have to keep in mind). After being inspired by the cell phone spectrum analyzer he set out to build a module compatible with the calculator by using an I2C port expander to interface with a radio receiver module. Now he can sniff out signals between 2.400 and 2.495 GHz and display the finds like in the image above.

[Thanks Cecil]


  1. Xiver says:

    Very nice. I’m going to try and duplicate this project. Thanks for the work and explaination Michael.

  2. Erik says:

    Oh this looks very nice, I might try this myself if I come across a cheap calculator. Because I have the ti83 so it will not work on mine I guess.

  3. GCL says:

    Amazing! I might try some of his other ideas.

    @Erik, according to his pages, it might even be portable.

  4. Ti83 says:

    From the article: “The software is for the 83+/83+ SE/84+, however with minor modifications it will work on any TI calculator.”

  5. M4CGYV3R says:

    ”the link port can be used as an I2C bus”


    That’s friggin awesome. I’ll have to break out my 84+ and try some stuff.

  6. 7e says:

    Sorry, i just had to link to this-> :P

  7. Cecil says:

    I looked at his documentation and the little bit of source and it seems that TI calcs interface is a basic Hi-Z interface.

    In other words it is a shared bus where any device can pull a line low. Both bits of the port are read/write so a simple bit banged I2C interface to flash, D/A, Temp or other devices is quite simple.

    Maybe a level shifter or buffer just in case as I have no idea on the sink levels or how the pull up’s are set up.

    All in all a great hack that can be widely expanded.


  8. sariel says:

    this is perfect! i just acquired an 84 silver the other day. sweet hack man! just need to hack together the IO cable

  9. kevin says:

    i think it’s great ,but i have not a ti counter.Unlucky

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