Reading registers on 2.8" TFT

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PhillHS
 
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Joined: Tue Jul 31, 2018 5:14 pm

Reading registers on 2.8" TFT

Post by PhillHS »

Hi All,

I'm using the 2.8" TFT display with resistive touch : https://www.adafruit.com/product/1770 with an STM32 Nucleo board and am accessing the display using SPI. I'm running a very hacked about and modified version of the AdaFruit Arduino library. I am able to access the display, write to it flip the screen round, print fonts on it etc, so the display is on the whole working.

However I am having trouble trying to read things like the Memory access control register (command 0x0b), though I can successfully read the display memory and use the undocumented op code (0xD9) to read the ID4 which returns 0x00, 0x49, 0xA0. Attempting to read the MAC register always seems to return something that is 0xX4, even if the value is set to something different immediately before by writing to it (command 0x36). For example write 0x48, read 0x24, write 0xF8, read 0xE4.

Anyone any idea of what is going on here, or how to correctly read the registers, which according to the datasheet should not require the 0xD9 code to read.

Cheers.

Phill.

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adafruit2
 
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Re: Reading registers on 2.8" TFT

Post by adafruit2 »

reading the registers on these displays is totally a hack, as you can see in the arduino library we wrote we don't depend on it at all - its not documented, we just sorta figured out some stuff :/

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