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LCD Graphics/Text Driver for cheap SPI LCD's with optional Touch screen support - Page 2 — Parallax Forums

LCD Graphics/Text Driver for cheap SPI LCD's with optional Touch screen support



  • Cluso99Cluso99 Posts: 17,716

    I recently bought a 1.3" 240x240 SPI color LCD and a 3.5" 480x320 SPI color LCD. I haven't had a chance yet to try with my driver - it should just be a simple parameter change.

  • As a newbie to everything Propeller, I very slowly set out to integrate the LCD Graphics/Text Driver with a 2.8" LCD, called from a BASIC program, all under flexprop. A month later now, have three nicely animated bar graphs (ea 80 bars) on screen, with 8x8 text number values floating animated, along side each, displaying levels derived from P2 smart pin A/D's (initialized and read from BASIC) with some simple DSP alg's in BASIC to process. BASIC alg uses floating point LOG, and math functions - yet with all this happening, bar graphs can update ~>100 times per second which is plenty fast and look great on the small LCD. Ready for a larger LCD so am in search of a few 4.0" 480x320 ST7796S SPI LCD's with Touch - haven't been able to find these on Amazon or E Bay - does anyone know of a source for these?

    BTW, even with my somewhat clunky BASIC code, the speed of this Graphics Driver on the P2 for this sort of application is incredible!..

  • @ synetcom

    Yes, if you are using Eric's Flexbasic you have discovered a mighty tool !!
    The compiler sneakily uses cache in critical places and gives you amazing speed. Have a look at the 'listing file' from the 'file' menu in the flexprop editor- Its a way of learning prop2 assembler and reveals its secrets.


  • @tritonium: Thanks for the info on viewing the flexprop 'listing file' will take a look later. Not a software engineer (do mostly RF hardware as an EE), but Eric's Flexbasic reminds me of programming a 1 MHz Apple II many years ago. P2 code execution is maybe 300x faster than the old Apple since running at 300 MHz, so indeed a mighty tool.

    Am approaching the point where my Basic code may grow too large and will probably be back here asking what to do next.

    I just found the 4" display on AliExpress, but my credit card won't allow the transaction (probably since overseas). So will modify my question - anyone know of a US source for the ST7796S 4.0" LCD's with touch?

  • Cluso99Cluso99 Posts: 17,716

    I bought mine on aliexpress but i have noticed the 4” seem to be out of stock. I did get find a 3.5” version from the same source. There’s a link in my 4.0” lcd thread.

  • @Cluso99: I found this 4" LCD display with touch based on ST7796S that appears in stock:

    Now working with a friend to purchase a few for me - earliest delivery April 20. It looks like it should work OK with the Graphics Driver, you think?

  • Cluso99Cluso99 Posts: 17,716

    Unfortunately the link wouldn’t work on my iphone???
    Anyway, all the LCDs seem to work with my driver. Only need to set the resolution.
    If you have different code, it should also work fine.

  • MicksterMickster Posts: 1,857


    If there is still more to figure out, you might want to grab the source for the Micromite/Armmite. They have done extensive work with these displays.



  • Hi

    Bought a serial 4 inch touch colour lcd from FYD Open Source Hardware (on Aliexpress) back in October for $11, so it seems your supplier is profiting from a shortage in the market with a massive markup!
    Supply and demand I guess.


  • Cluso99Cluso99 Posts: 17,716

    Ouch. Just managed to follow the link.

    I paid ~$12 for both 4” and 3.5” 480x320 SPI shipped. All prices seem to be rising but $50 is ridiculous..

  • Cluso99Cluso99 Posts: 17,716

    Just tried my 1.3" 240x240 ST7789

    After changing the settings to use the 240x240, I found that I needed to download/run the twice for it to work. Also note the background is white instead of what should be black. Need to investigate further when time permits. I have tried both hardware and software resets, and two resets but this doesn't fix my need to load twice. There is obviously something in the setup that needs changing.

    I measured the Vcc current and it is ~13.6mA so I am not powering it with P2 pins at least for now. The 1.44" 128x128 IIRC was around 2mA which is why I powered it from the P1 and P2 pins.

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