Micropython driver for XPT2046 touch, especially for Lilygo T-HMI device
For T-HMI, use the firmware from russhughes.
Flashing instructions: Place device into flash mode by pressing and holding the BOOT button, then press and release the RESET button and finally release the BOOT button (these are the RST and BOOT switches on the side of the device, near the SD card reader).
On Linux:
esptool.py --chip esp32s3 --port /dev/ttyACM0 erase_flash
On Windows:
./python.exe -u -m esptool --chip esp32s3 --port COM27 erase_flash
On Linux:
esptool.py --chip esp32s3 --port /dev/ttyACM0 write_flash -z 0 firmware.bin
On Windows:
./python.exe -u -m esptool --chip esp32s3 --port COM27 --baud 460800 write_flash -z 0x0 firmware.bin
Finally, unplug and plug the device.
This driver is based on the original version from rdagger. The calibration is quite simple (and can be improved in the future).
First, a SPI bus must be created.
from machine import SPI, Pin
spi = SPI(1, baudrate=1000000)
spi.init(sck=Pin(01), mosi=Pin(03), miso=Pin(04))
cs = Pin(2, mode=Pin.OUT, value=1)
Declare the touch device
xpt = Touch(spi, cs=cs, int_pin=int_pin)
The int_pin argument is mandatory. For T-HMI, use:
int_pin = Pin(9)
Arguments are: xmin, xmax, ymin, ymax, width, height, orientation. Use the Calibration.py script to get the values. On my T-HMI device, I found that
xmin = 150
xmax = 1830
ymin = 150
ymax = 1830
are fairly good. Then:
xpt = Touch(spi, cs=cs, int_pin=int_pin)
xpt.calibrate(xmin, xmax, ymin, ymax, width, height, orientation)
Note that here, width is the largest value and height is the lowest one. So, independently of the orientation of the display, on the T-HMI 320 x 240 display, you have either:
xpt.calibrate(150, 1830, 150, 1830, 320, 240, 0)
or
xpt.calibrate(150, 1830, 150, 1830, 320, 240, 1)
Provides the x and y coordinates using the display reference. The origin is in the upper left corner.
x, y = xpt.get_touch()
This method can only be used after calling the calibrate() method. Depending on the calibration accuracy, it can provide negative coordinates or coordinates higher than the size of the display. An optional argument is used to clip the provided values to the display size:
x, y = xpt.get_touch(True)
Returns True if the display was touched or False otherwise.
Used to change the orientation of the display. Argument values are the same as russhugjes's:
| Index | Rotation |
|---|---|
| 0 | Portrait (0 degrees) |
| 1 | Landscape (90 degrees) |
| 2 | Reverse Portrait (180 degrees) |
| 3 | Reverse Landscape (270 degrees) |
Provides the raw values from the device, without any reference to the display size. The origin is in the lower right corner. This is only used in the calibration script, but you may not want to use it.
x, y = xpt.raw_touch()
Use this to get the calibration values for your touch device. Change the orientation value in line 17 as desired.
A simple example of how to use the driver. It is based on calibration values for my T-HMI: change the lines 22-25 according to the values provided by the above script.
Similar but using the interrupt to get the coordinates.
Game of Simon: load and run it. The orientation is 0 (portrait, USB connector bottom)