T-Display S3 Pro Touchscreen Support - CST226SE Chip Help Needed
Hardware & Setup
- Device: LilyGO T-Display S3 Pro (ESP32-S3) T-Display S3 Pro – LILYGO® - Githup Repo with sample code
- Touchscreen: CST226SE (confirmed from official Chinese datasheet / github issue)
- ESPHome Version: 2025.5.2
- Framework: ESP-IDF
Problem Summary
I’ve been trying to get the touchscreen working on the T-Display S3 Pro and have discovered it uses a CST226SE chip, not the commonly assumed GT911 or CST816. The display works perfectly, but touch detection remains elusive despite successful I2C communication.
What We’ve Tried
Uploaded the stock firmware and confirmed touch screen works.
1. Initial Driver Attempts
- GT911 touchscreen component: Failed with “Failed to read calibration values from touchscreen”
- CST816 driver: Failed - not compatible with CST226SE hardware
- FT5x06 and TT21100: Also incompatible
2. Hardware Discovery
Through the official LilyGO Chinese documentation and the utilities.h file
, we confirmed:
- I2C Address: 0x6A
- Pins:
- SDA: GPIO5
- SCL: GPIO6
- Reset: GPIO13
- Interrupt: GPIO21
- Power Enable: GPIO38
3. CST226SE Register Protocol Implementation
From the official Chinese datasheet, we implemented the complete register map:
- 0x00: Work mode (0x00 = NORMAL, 0x40 = SLEEP)
- 0x01: Proximity detection
- 0x02: Touch point count
- 0x03-0x06: Touch coordinates with event flags and touch ID
4. Initialization Sequence
We’ve tried multiple initialization approaches:
- Power cycling with GPIO38
- Proper reset sequence with GPIO13
- Wake-up command (0xA5, 0x00)
- Calibration command (0xD104)
- Setting NORMAL mode (register 0x00 = 0x00)
Current Status
Working: Display, WiFi, I2C communication with CST226SE
Not Working: Actual touch detection (coordinates remain static)
The chip responds correctly at I2C address 0x6A and we can read all registers, but physical touches don’t register any coordinate changes or touch count updates.
Working Configuration
Here’s our current ESPHome config with display working and CST226SE communication established:
esphome:
name: t-display-s3-pro-touch-screen
on_boot:
then:
- output.turn_on: touchscreen_power
- delay: 10ms
- output.turn_off: touchscreen_reset # Reset low
- delay: 10ms
- output.turn_on: touchscreen_reset # Reset high
- delay: 100ms
- lambda: |-
// Initialize CST226SE according to official manual
uint8_t normal_mode[] = {0x00, 0x00}; // NORMAL mode
id(bus_a).write(0x6A, normal_mode, sizeof(normal_mode));
ESP_LOGI("touch", "CST226SE set to NORMAL mode");
// Calibration command from datasheet
uint8_t cal_cmd[] = {0xD1, 0x04};
id(bus_a).write(0x6A, cal_cmd, sizeof(cal_cmd));
- delay: 200ms
esp32:
board: esp32-s3-devkitc-1
framework:
type: esp-idf
# Pin configuration from official LilyGO utilities.h
output:
- platform: ledc
frequency: 9765Hz
pin: GPIO48
id: backlight_output
- platform: gpio
pin: GPIO38
id: touchscreen_power
- platform: gpio
pin: GPIO13
id: touchscreen_reset
light:
- platform: monochromatic
output: backlight_output
name: LCD Backlight
id: led
restore_mode: ALWAYS_ON
# Display works perfectly
spi:
- id: spi_id_3
interface: any
clk_pin: 18
mosi_pin: 17
display:
- platform: mipi_spi
model: t-display-s3-pro
id: my_display
lambda: |-
// Your display rendering code here
it.print(10, 10, id(roboto), "Display Working!");
# I2C with CST226SE - communication works
i2c:
sda: GPIO5
scl: GPIO6
id: bus_a
frequency: 100kHz
scan: true
# CST226SE register reading (for debugging)
interval:
- interval: 1s
then:
- lambda: |-
uint8_t start_reg = 0x00;
id(bus_a).write(0x6A, &start_reg, 1, false);
uint8_t reg_data[8];
auto result = id(bus_a).read(0x6A, reg_data, sizeof(reg_data));
if (result == esphome::i2c::ERROR_OK) {
uint8_t work_mode = reg_data[0];
uint8_t touch_count = reg_data[2];
uint16_t x = ((reg_data[3] & 0x0F) << 8) | reg_data[4];
uint16_t y = ((reg_data[5] & 0x0F) << 8) | reg_data[6];
ESP_LOGI("touch", "CST226SE: mode=0x%02X, count=%d, x=%d, y=%d",
work_mode, touch_count, x, y);
}
font:
- file: "gfonts://Roboto"
id: roboto
size: 20
Questions for the Community
- Has anyone successfully implemented CST226SE support in ESPHome?
- Are there additional initialization steps needed for CST226SE touch sensing?
- Should we consider creating a custom ESPHome component for CST226SE?
- Any insights on why I2C communication works but touch detection doesn’t?
@clydebarrow I saw you have good experience in this area and closely followed in post EspHome on T-Display S3 Pro but as someone did mention in Any way to get the new T-Display-S3 AMOLED to work with ESPHome? that there was no driver for CST226SE.
Debug Output
The chip responds with consistent values:
CST226SE: mode=0x00, prox=0x06, count=29(0), x=2592, y=862, event=0x00, id=1
But these values never change despite physical touches on the screen.
Request
If anyone has experience with CST226SE or similar Chipone touch controllers, or has successfully got touch working on T-Display S3 Pro, I’d greatly appreciate any guidance!
Thanks in advance for any help! 
Hardware confirmed through official LilyGO documentation and Chinese CST226SE datasheet
Post wirtten with help of AI after hours of vibe debugging with Claude Sonnet 4
Thanks! Works with that!
