using A92QN LCD under control of PIC SPI at assembler level

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lovelacefan
 
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using A92QN LCD under control of PIC SPI at assembler level

Post by lovelacefan »

Greetings from the Mother Country (at least, it was until 4th July 1776...)

I have just bought a 2.8" touchscreen TFT LCD, and the instructions seem quite clear for connecting it up. However, I may have missed something, as I can't find out how to do individual pixel addressing via the SPI interface at assembler level. I know of course that you have libraries written in higher-level code, but I am wishing to operate the display from code which I am using to operate various musical instruments.

I make theremins, laser harps and similar gadgets (see for example (A) https://www.youtube.com/watch?v=n_b85AM8Pho or (B) https://www.youtube.com/watch?v=v80hZUfJ0hA at 1 minute 32 seconds). I am currently designing an instrument to turn human voice into orchestral sound sequences, and it is this device I need the display for.

Obviously I can try sending "intelligent random data", then interpreting the results I observe on the display, but it is going to be way quicker if I know what the control byte stream should look like. It's also important to know if there are any speed restrictions on the SPI transfer rate.

Please can you help an ageing engineer? Thanks

Richard Helyer aka lovelacefan

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Franklin97355
 
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Re: using A92QN LCD under control of PIC SPI at assembler le

Post by Franklin97355 »

If you are using the 1770 product the PDF for the controller is here http://www.adafruit.com/datasheets/ILI9341.pdf If you have a different product let us know which one you have.

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lovelacefan
 
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Re: using A92QN LCD under control of PIC SPI at assembler le

Post by lovelacefan »

Many thanks. Looks like good bedtime reading.

With large-scale datasheets, sometimes people publish a concise summary to save their peers wasted time in the future. Engineers like to save time by not re-inventing the wheel if possible.

Before I start in earnest, do you know if any such summaries exist, please? Since all of the control and data traffic goes via SPI, it may be that for "cheating" purposes, someone (maybe the fair Limor F herself) has a document which has sets of streams of numbers for achieving specific effects, e.g. initialise stream, light an individual pixel, and so on.

If there are any shortcuts, this would be really time-saving to know.

Conversely, if there are not any such shortcuts, would you like me to publish such sets of byte streams (when I have derived them) somehow, via adafruit?

I am hoping, however, someone has had the intelligence and foresight to realise that the problem I wish to solve is likely to be a commonplace one, and so will have documented the sort of streams I describe above.

Blessings

lovelacefan a.k.a. Richard Helyer

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