You can make a baby and a bitmap in nine months

A project log for VT-69 Handheld Terminal

It's a dumb terminal. You can connect a Raspberry Pi to it.

BenchoffBenchoff 10/16/2019 at 17:423 Comments

The last update for this project was a realization that a 'dumb' display would cost too much; the driver chip was too expensive, and if I didn't want to go with a driver chip, the microcontroller would be too expensive. The solution to this problem was to use a display with built-in graphics RAM, in this case a display with the NT35510 controller chip. There's a problem with this solution - no one has a driver for this display, or at least one that is portable to other (read: modern) microcontrollers.

...Which means I need to write a TFT driver. This took nine months. Here's the result:

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While banging my head against the wall figuring out how to get the code to work, I did most of the remainder of the engineering on the mechanical and electronics. Results below:

Of note are some small, 0.3mm high ribs on the back. This design feature is directly lifted from an old PowerBook, and it really breaks up what would otherwise be a featureless plane on the back of the device.

The last revision of the hardware was too tall, and now I have plastic that will fit in a flat rate shipping box. It's a little taller, which should allow for the Raspberry Pi expansion header. All in all, a sleeker enclosure.

This will be the last update until I have a reasonably complete prototype. The only thing left to do before that is wire up the keyboard. There's keyboard code to write, but that's just tedious, not actually difficult.

I would like to reiterate it took nine months to write this TFT driver.


Krzysztof wrote 02/14/2020 at 11:16 point

> I would like to reiterate it took nine months to write this TFT driver.

9 months of 8h daily? It took me 9 months of wall time to execute one side project, but total run-time was about 80h.

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risknc wrote 02/14/2020 at 04:31 point

Lookin good! 

Want an aluminium enclosure as a one off? I got a Haas TM2P in the garage now, this is the perfect practice side project for the stock material I've got laying around :P 

I could probably machine one (design looks pretty straightforward). Send me the CAD!!!

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Benchoff wrote 02/14/2020 at 04:42 point

lemme do a printed prototype first before that. You might be able to screw around with this, though:

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