Register layout for the GoodIX GT911 capacitive touch controller. More...

#include <stdint.h>

Include dependency graph for ra8_touch_gt911_regs.h:

This graph shows which files directly or indirectly include this file:

Enumerations
enum	ra8_touch_gt911_addr_t : uint8_t { k_ra8_touch_gt911_addr_low = 0x5DU , k_ra8_touch_gt911_addr_high = 0x14U }
	I2C target addresses for the GT911. More...
enum	ra8_touch_gt911_reg_t : uint16_t { k_ra8_touch_gt911_reg_command = 0x8040U , k_ra8_touch_gt911_reg_config = 0x8047U , k_ra8_touch_gt911_reg_product = 0x8140U , k_ra8_touch_gt911_reg_firmware = 0x8144U , k_ra8_touch_gt911_reg_xres = 0x8146U , k_ra8_touch_gt911_reg_yres = 0x8148U , k_ra8_touch_gt911_reg_status = 0x814EU , k_ra8_touch_gt911_reg_point0 = 0x814FU }
	16-bit register pointers used by the driver. More...
enum	ra8_touch_gt911_cmd_t : uint8_t { k_ra8_touch_gt911_cmd_clear_status = 0x00U , k_ra8_touch_gt911_cmd_software_reset = 0x02U }
	Values written into k_ra8_touch_gt911_reg_command. More...
enum	ra8_touch_gt911_status_mask_t : uint8_t { k_ra8_touch_gt911_status_count_mask = 0x0FU , k_ra8_touch_gt911_status_large_mask = 0x40U , k_ra8_touch_gt911_status_ready_mask = 0x80U }
	Bit layout of the status byte at k_ra8_touch_gt911_reg_status. More...
enum	ra8_touch_gt911_geometry_t : uint8_t { k_ra8_touch_gt911_max_points = 5U , k_ra8_touch_gt911_point_bytes = 8U , k_ra8_touch_gt911_id_bytes = 4U , k_ra8_touch_gt911_reg_ptr_bytes = 2U }
	Compile-time geometry constants for the controller. More...
enum	ra8_touch_gt911_point_offset_t : uint8_t { k_ra8_touch_gt911_point_off_track = 0U , k_ra8_touch_gt911_point_off_x_lsb = 1U , k_ra8_touch_gt911_point_off_x_msb = 2U , k_ra8_touch_gt911_point_off_y_lsb = 3U , k_ra8_touch_gt911_point_off_y_msb = 4U , k_ra8_touch_gt911_point_off_size_lsb = 5U , k_ra8_touch_gt911_point_off_size_msb = 6U , k_ra8_touch_gt911_point_off_reserved = 7U }
	Byte offsets of each field inside one 8-byte point record. More...

Detailed Description

Register layout for the GoodIX GT911 capacitive touch controller.

Tag: [Ring 3 / HAL] {World: NS}

The GT911 is a 5-point projected-capacitive touch IC commonly paired with parallel TFT panels in the 5"-10" size range. It is the touch backend for the EK-RA8D2 ereader carrier this project targets, sitting on the I2C0 bus alongside other low-speed peripherals.

Address space (16-bit register pointers):

Offset	Name	Width	Purpose
0x8040	GTP_COMMAND	8	Command (0x00 sleep, 0x01 wake)
0x8047	CONFIG_VERSION	8	First byte of config block
0x8140	PRODUCT_ID (4 char)	32	"911"\0 ASCII id
0x8144	FIRMWARE_VERSION	16	Little-endian firmware revision
0x8146	X_RESOLUTION	16	Reported panel X resolution
0x8148	Y_RESOLUTION	16	Reported panel Y resolution
0x814E	STATUS	8	bit7 buffer-ready, bits[3:0] cnt
0x814F	POINT[0..4] base	8x5	Five 8-byte point records

Per-point record (8 bytes, little-endian for the 16-bit fields):

Off	Field	Notes
0	track_id	Persistent contact id, 0..15
1	x_lsb	X coordinate low byte
2	x_msb	X coordinate high byte
3	y_lsb	Y coordinate low byte
4	y_msb	Y coordinate high byte
5	size_lsb	Contact area size low byte (pressure)
6	size_msb	Contact area size high byte
7	reserved	Always 0

Cross-checked against GoodIX "GT911 Programming Guide" rev 0.1 (publicly distributed reference; this project does not vendor the document).

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Definition in file ra8_touch_gt911_regs.h.

Enumeration Type Documentation

◆ ra8_touch_gt911_addr_t

enum ra8_touch_gt911_addr_t : uint8_t

I2C target addresses for the GT911.

The GT911 latches its 7-bit address from the INT pin level at reset: INT low yields 0x5D, INT high yields 0x14. The factory default on the EK-RA8D2 ereader carrier is 0x5D.

Enumerator
k_ra8_touch_gt911_addr_low	Default 7-bit target address.
k_ra8_touch_gt911_addr_high	Alternate 7-bit target address.

Definition at line 66 of file ra8_touch_gt911_regs.h.

◆ ra8_touch_gt911_cmd_t

enum ra8_touch_gt911_cmd_t : uint8_t

Values written into k_ra8_touch_gt911_reg_command.

Enumerator
k_ra8_touch_gt911_cmd_clear_status	Acknowledge a touch frame.
k_ra8_touch_gt911_cmd_software_reset	Soft reset.

Definition at line 90 of file ra8_touch_gt911_regs.h.

◆ ra8_touch_gt911_geometry_t

enum ra8_touch_gt911_geometry_t : uint8_t

Compile-time geometry constants for the controller.

Enumerator
k_ra8_touch_gt911_max_points	Max simultaneous contacts.
k_ra8_touch_gt911_point_bytes	Bytes per per-point record.
k_ra8_touch_gt911_id_bytes	Length of PRODUCT_ID payload.
k_ra8_touch_gt911_reg_ptr_bytes	16-bit register-pointer width.

Definition at line 109 of file ra8_touch_gt911_regs.h.

◆ ra8_touch_gt911_point_offset_t

enum ra8_touch_gt911_point_offset_t : uint8_t

Byte offsets of each field inside one 8-byte point record.

Enumerator
k_ra8_touch_gt911_point_off_track	track_id field.
k_ra8_touch_gt911_point_off_x_lsb	X low byte.
k_ra8_touch_gt911_point_off_x_msb	X high byte.
k_ra8_touch_gt911_point_off_y_lsb	Y low byte.
k_ra8_touch_gt911_point_off_y_msb	Y high byte.
k_ra8_touch_gt911_point_off_size_lsb	Size low byte.
k_ra8_touch_gt911_point_off_size_msb	Size high byte.
k_ra8_touch_gt911_point_off_reserved	Always 0.

Definition at line 120 of file ra8_touch_gt911_regs.h.

◆ ra8_touch_gt911_reg_t

enum ra8_touch_gt911_reg_t : uint16_t

16-bit register pointers used by the driver.

Enumerator
k_ra8_touch_gt911_reg_command	Command register.
k_ra8_touch_gt911_reg_config	First byte of config block.
k_ra8_touch_gt911_reg_product	4-byte product id.
k_ra8_touch_gt911_reg_firmware	Firmware revision.
k_ra8_touch_gt911_reg_xres	Reported X resolution.
k_ra8_touch_gt911_reg_yres	Reported Y resolution.
k_ra8_touch_gt911_reg_status	Status / point-count byte.
k_ra8_touch_gt911_reg_point0	First per-point record.

Definition at line 75 of file ra8_touch_gt911_regs.h.

◆ ra8_touch_gt911_status_mask_t

enum ra8_touch_gt911_status_mask_t : uint8_t

Bit layout of the status byte at k_ra8_touch_gt911_reg_status.

Enumerator
k_ra8_touch_gt911_status_count_mask	bits[3:0] active touch count.
k_ra8_touch_gt911_status_large_mask	bit6 large-detect.
k_ra8_touch_gt911_status_ready_mask	bit7 buffer-ready.

Definition at line 99 of file ra8_touch_gt911_regs.h.

Enumerations