Hi,

I am using a TFT from Winstar that includes a GT911 touch controller. I need to be able to modify some registers so it works with a thicker cover glass.

I am able to communicate with the GT911 and get touch data so I know my I2C functions are working OK.

This is the sequence I follow :-

1. Read the entire config data area (0x8047 to 0x8100) into an array (I can see that this data looks valid)
2. Change the touch / release threshold registers (0x8053 / 0x8054) in the array to lower values for the cover glass
3. Calculate the new checksum (from 0x8047 to 0x80FE)
4. Write the checksum byte to array location 0x80FF
5. Write 0x01 to the fresh location (0x8100)
6. Write 0x00 to the version location (0x8047) – I have also tried writing 0x42
7. Write the entire array back to the GT911 (0x8047 to 0x8100)

What I am seeing is that none of the registers change. If I read them back again they are exactly as they were before.

I feel that I am missing something fundamental that is required for changing the config.

I am not using an operating system or driver - this is low level code running on a microcontroller.

Any help that anyone could give would be very much appreciated! Thanks.