Able to build a VERY basic KMK image for Feather M4 Express, flashable over UF2 only

kmk/circuitpython/matrix.py

@@ -2,6 +2,7 @@ import digitalio
 
 from kmk.common.abstract.matrix_scanner import AbstractMatrixScanner
 from kmk.common.consts import DiodeOrientation
+from kmk.common.event_defs import matrix_changed
 
 
 class MatrixScanner(AbstractMatrixScanner):
@@ -17,6 +18,7 @@ class MatrixScanner(AbstractMatrixScanner):
         self.cols = [digitalio.DigitalInOut(pin) for pin in cols]
         self.rows = [digitalio.DigitalInOut(pin) for pin in rows]
         self.diode_orientation = diode_orientation
+        self.last_pressed_len = 0
 
         if self.diode_orientation == DiodeOrientation.COLUMNS:
             self.outputs = self.cols
@@ -35,15 +37,22 @@ class MatrixScanner(AbstractMatrixScanner):
         for pin in self.inputs:
             pin.switch_to_input(pull=digitalio.Pull.DOWN)
 
-    def _normalize_matrix(self, matrix):
-        return super()._normalize_matrix(matrix)
+    def scan_for_pressed(self):
+        pressed = []
 
-    def raw_scan(self):
-        matrix = []
-
-        for opin in self.outputs:
+        for oidx, opin in enumerate(self.outputs):
             opin.value = True
-            matrix.append([ipin.value for ipin in self.inputs])
+
+            for iidx, ipin in enumerate(self.inputs):
+                if ipin.value:
+                    pressed.append(
+                        (oidx, iidx) if self.diode_orientation == DiodeOrientation.ROWS else (iidx, oidx)  # noqa
+                    )
+
             opin.value = False
 
-        return self._normalize_matrix(matrix)
+        if len(pressed) != self.last_pressed_len:
+            self.last_pressed_len = len(pressed)
+            return matrix_changed(pressed)
+
+        return None  # The default, but for explicitness