GPS for graphing calculators


Kerm Martian from Cemetech has documented a GPS for graphing calculators project build:

Graphing calculators are nothing less than powerful pocket computers, capable of doing many of the same things as smartphones, desktops, and laptops. Given that they have reasonably fast processors, a display, memory, and ports to interface with the outside world, I set out to making graphing calculators capable of determining their location using standard GPS hardware. I started with the TI-84 Plus / Silver Edition series of graphing calculators, which have a 15MHz processor, a 96×64-pixel monochrome screen, rudimentary timers (as well as one 32KHz crystal timer), and perhaps most importantly, two ports to interface with the outside world. One is a USB OTG port, a mini-USB port capable of acting as either a host or device, and therefore capable of producing 5V for peripherals. The other is a “serial” I/O port with two bidirectional TTL-level data lines. For my project, I chose to use the USB port for power, and the I/O port to communicate with a TTL serial GPS module. I created both the hardware and software necessary to make the project a reality, then suffered through two weeks of trying to get a GPS fix amid the metal canyons of a major US city.

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  1. I’ve always thought Digilent [or Terasic, etc] should make a development platform that is also a calculator. All those buttons, LED’s & displays wrapped up with a battery in a portable format. Heck, clock it under 133MHz and your expansion interface could probably even get away with 0.1″ headers, like the old PATA interface…

    For a triumph in coding, look to the WP-34S [a re-fashioned HP30b]. For hardware interfacing, there’s this. I only hope the group working on the WP-43S {successor to the 34S] rise to the challenge, and produce something equally hardware-hacking friendly.

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