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TACHYON hardware: ST9720 based 128x64 graphics LCD update — Parallax Forums

TACHYON hardware: ST9720 based 128x64 graphics LCD update

Peter JakackiPeter Jakacki Posts: 10,193
edited 2015-07-11 23:08 in Propeller 1
You might wonder who might be interested in only a monochrome 128x64 graphic display when higher resolution TFTs are cheap. Well there's something to be said for transreflective STN LCD displays as they are easily viewable in bright sunlight and hence are used for industrial applications. The graphics is suitable for display 8 lines of 21 characters or just 2 lines of 8 characters if you want the big Propeller font in all it's glory.

When operated in serial mode you really don't even need any I/O other than the chip select and borrow the clock and data from the I2C lines. There's an extra pin I use for backlight control otherwise leave it on.

I published a driver a while back but here's an updated one with stream mode so you substitute it for an output device in Tachyon. It's very easy to use. You will also need the updated FONT5X7.fth file loaded beforehand.

<Google webpage document link>

st7920 lcd.jpg


  • Just wondering if you are able to use the entire propeller font including the electronic symbol characters. The st7920 has a graphics mode as well as character mode, if I am not mistaken. It might be some time before I can interface to it, but thanks for posting the code, I will check it out. Feeling guilty for not getting the graphics only lcd.

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