adafruit_touchscreen

CircuitPython library for 4-wire resistive touchscreens

  • Author(s): ladyada

Implementation Notes

Software and Dependencies:

class adafruit_touchscreen.Touchscreen(x1_pin: Pin, x2_pin: Pin, y1_pin: Pin, y2_pin: Pin, *, x_resistance: int | None = None, samples: int = 4, z_threshold: int = 10000, calibration: Tuple[Tuple[int, int], Tuple[int, int]] | None = None, size: Tuple[int, int] | None = None, invert_pressure: bool = True)

A driver for common and inexpensive resistive touchscreens. Analog input capable pins are required to read the intrinsic potentiometers

Create the Touchscreen object. At a minimum you need the 4 pins that will connect to the 4 contacts on a screen. X and Y are just our names, you can rotate and flip the data if you like. All pins must be capable of becoming DigitalInOut pins. y2_pin, x1_pin and x2_pin must also be capable of becoming AnalogIn pins. If you know the resistance across the x1 and x2 pins when not touched, pass that in as ‘x_resistance’. calibration is a tuple of two tuples, the default is ((0, 65535), (0, 65535)). The numbers are the min/max readings for the X and Y coordinate planes, respectively. To figure these out, pass in no calibration value or size value and read the raw minimum and maximum values out while touching the panel. size is a tuple that gives the X and Y pixel size of the underlying screen. If passed in, we will automatically scale/rotate so touches correspond to the graphical coordinate system.

Parameters:

  • x1_pin (Pin) – Data pin for Left side of the screen. Must also be capable of becoming AnalogIn pins.

  • x2_pin (Pin) – Data pin for Right side of the screen. Must also be capable of becoming AnalogIn pins.

  • y1_pin (Pin) – Data pin for Bottom side of the screen.

  • y2_pin (Pin) – Data pin for Top side of the screen. Must also be capable of becoming AnalogIn pins.

  • x_resistance (int) – If you know the resistance across the x1 and x2 pins when not touched, pass that in as x_resistance

  • samples (int) – change by adjusting samples arg. Defaults to 4

  • z_threshold (int) – We can also detect the ‘z’ threshold, how much its pressed. We don’t register a touch unless its higher than z_threshold

  • calibration ((int,int),(int,int)) – A tuple of two tuples The numbers are the min/max readings for the X and Y coordinate planes, respectively. Defaults to ((0, 65535), (0, 65535))

  • size (int,int) – The dimensions of the screen as (x, y).

  • invert_pressure (bool) – Whether to invert the pressure values. Some touchscreens and drivers may need this to be changed to False in order to properly register touches.

property touch_point: Tuple[int, int, int] | None

A tuple that represents the x, y and z (touch pressure) coordinates of a touch. Or, None if no touch is detected

adafruit_touchscreen.map_range(x: float, in_min: int, in_max: int, out_min: int, out_max: int) → float

Maps a number from one range to another.

Note

This implementation handles values < in_min differently than arduino’s map function does.

Returns:

Returns value mapped to new range

Return type:

float