Driving an LCD shutter with a PIC 16F917

lcd_off lcd_on

This is a prototype I put together using an LCD shutter from a 5 dollar novelty keychain. I’m driving the shutter using the built in LCD segment driver on a PIC 16F917. The ultimate goal of this is to investigate the feasibility of adding stereoscopic support to my graphics engine by triggering the LCD with a photo sensor in the corner of the screen. Every even frame would have a light square in the corner and a black square in the odd frames.

The switching response in the LCD seems pretty poor. In the video below I’m strobing it ~18Hz. The red LED on the bread board is switched on when the LCD is dark. In this test the LED shines right through when it should be blocked. I don’t know whether or not the issue is with how the shutter is being driven or if it’s a response time issue. I’ll have to do more testing to figure that out. I don’t have time to move forward with this so I’m going to have to shelve it for now…

2 thoughts on “Driving an LCD shutter with a PIC 16F917

  1. Ray

    Nice video! Do you prepare circuit diagrams for things like this to document your experiments? Or just wire them ad-hoc?

  2. millerb Post author

    For this one I followed the example circuit in the data sheet for the PIC. The only thing I did different was using a 30 MHz oscillator. If I needed to create something more complex I would at the very least sketch it out on a sheet of paper.

    One thing I noticed about the oscillators (I tried three different ones) is that they dump a ton of noise onto the power rail, something I didn’t observe when using a crystal. At some point I’d like to go back and try a few different types of filtering circuits.


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