working-ish?

Author: ladyada

adafruit_touchscreen.py

@@ -0,0 +1,77 @@
+from analogio import AnalogIn
+from digitalio import DigitalInOut, Direction, Pull
+
+def map_range(x, in_min, in_max, out_min, out_max):
+    """
+    Maps a number from one range to another.
+    Note: This implementation handles values < in_min differently than arduino's map function does.
+    :return: Returns value mapped to new range
+    :rtype: float
+    """
+    mapped = (x-in_min) * (out_max - out_min) / (in_max-in_min) + out_min
+    if out_min <= out_max:
+        return max(min(mapped, out_max), out_min)
+    return min(max(mapped, out_max), out_min)
+
+class Touchscreen:
+
+    def __init__(self, x1_pin, x2_pin, y1_pin, y2_pin, *,
+                 x_resistance=None, samples=4, z_threshhold=10000,
+                 calibration=None, size=None):
+        """Since we use the pins as both analog and digital, they must be pins
+        not DigitalInOuts!"""
+        self._xm_pin = x1_pin
+        self._xp_pin = x2_pin
+        self._ym_pin = y1_pin
+        self._yp_pin = y2_pin
+        self._rx_plate = x_resistance
+        self._xsamples = [0] * samples
+        self._ysamples = [0] * samples
+        if not calibration:
+            calibration = ((0, 65535), (0, 65535))
+        self._calib = calibration
+        self._size = size
+        self._zthresh = z_threshhold
+
+    @property
+    def touch_point(self):
+        with DigitalInOut(self._yp_pin) as yp:
+            with DigitalInOut(self._ym_pin) as ym:
+                with AnalogIn(self._xp_pin) as xp:
+                    yp.switch_to_output(True)
+                    ym.switch_to_output(False)
+                    for i in range(len(self._xsamples)):
+                        self._xsamples[i] = xp.value
+        x = sum(self._xsamples) / len(self._xsamples)
+        x_size = 65535
+        if self._size:
+            x_size = self._size[0]
+        x = int(map_range(x, self._calib[0][0], self._calib[0][1], 0, x_size))
+
+        with DigitalInOut(self._xp_pin) as xp:
+            with DigitalInOut(self._xm_pin) as xm:
+                with AnalogIn(self._yp_pin) as yp:
+                    xp.switch_to_output(True)
+                    xm.switch_to_output(False)
+                    for i in range(len(self._ysamples)):
+                        self._ysamples[i] = yp.value
+        y = sum(self._ysamples) / len(self._ysamples)
+        y_size = 65535
+        if self._size:
+            y_size = self._size[1]
+        y = int(map_range(y, self._calib[1][0], self._calib[1][1], 0, y_size))
+
+        z1 = z2 = z = None
+        with DigitalInOut(self._xp_pin) as xp:
+            xp.switch_to_output(False)
+            with DigitalInOut(self._ym_pin) as ym:
+                ym.switch_to_output(True)
+                with AnalogIn(self._xm_pin) as xm:
+                    z1 = xm.value
+                with AnalogIn(self._yp_pin) as yp:
+                    z2 = yp.value
+        #print(z1, z2)
+        z = 65535 - (z2-z1)
+        if z > self._zthresh:
+            return (x, y, z)
+        return None

examples/touchscreen_simpletest.py

@@ -0,0 +1,14 @@
+import adafruit_touchscreen
+import board
+
+# These pins are used as both analog and digital! XR and YU must be analog
+# and digital capable. XL and YD just need to be digital
+ts = adafruit_touchscreen.Touchscreen(board.TOUCH_XL, board.TOUCH_XR,
+                                      board.TOUCH_YD, board.TOUCH_YU,
+                                      calibration=((5200, 59000), (5800, 57000)),
+                                      size=(320,240))
+
+while True:
+    p = ts.touch_point
+    if p:
+        print(p)