If you read register 0x8000 and always get 0x00, your I²C is working, but the GT911 is not initialized. Ensure you performed the hardware reset sequence correctly. Many libraries forget to pull INT low before reset.
A crucial plot point in the GT911 register map story is the I2C Address. The GT911 is unique because it can operate on two different addresses, and the register map is accessed differently depending on how the chip wakes up. gt911 register map
The community reverse-engineered the "Handshake Protocol." They found that during power-up, the state of the Interrupt and Reset pins dictated the I2C address. If you read register 0x8000 and always get
This discovery explained why some GT911 screens worked instantly with Arduino libraries and others failed silently—the developer was shouting at the wrong address. This discovery explained why some GT911 screens worked
0x8141 — Number of touch points (n) (1 byte).
0x8142–0x8151 — Touch data block for point 1..n (6–8 bytes each), repeated per point:
Example: for point i, offset = 0x8143 + (i-1)*8 (confirm per device).