A basic 2x2 matrix that can auto-flash to a Feather with a compatible bootloader

kmk/circuitpython/matrix.py

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+import digitalio
+
+from kmk.common.consts import DiodeOrientation
+
+
+class MatrixScanner:
+    def __init__(self, cols, rows, diode_orientation=DiodeOrientation.COLUMNS):
+        # A pin cannot be both a row and column, detect this by combining the
+        # two tuples into a set and validating that the length did not drop
+        #
+        # repr() hackery is because CircuitPython Pin objects are not hashable
+        unique_pins = {repr(c) for c in cols} | {repr(r) for r in rows}
+        if len(unique_pins) != len(cols) + len(rows):
+            raise ValueError('Cannot use a pin as both a column and row')
+
+        self.cols = [digitalio.DigitalInOut(pin) for pin in cols]
+        self.rows = [digitalio.DigitalInOut(pin) for pin in rows]
+        self.diode_orientation = diode_orientation
+
+        if self.diode_orientation == DiodeOrientation.COLUMNS:
+            self.outputs = self.cols
+            self.inputs = self.rows
+        elif self.diode_orientation == DiodeOrientation.ROWS:
+            self.outputs = self.rows
+            self.inputs = self.cols
+        else:
+            raise ValueError('Invalid DiodeOrientation: {}'.format(
+                self.diode_orientation,
+            ))
+
+        for pin in self.outputs:
+            pin.switch_to_output()
+
+        for pin in self.inputs:
+            pin.switch_to_input(pull=digitalio.Pull.DOWN)
+
+    def _normalize_matrix(self, matrix):
+        '''
+        We always want to internally look at a keyboard as a list of rows,
+        where a "row" is a list of keycodes (columns).
+
+        This will convert DiodeOrientation.COLUMNS matrix scans into a
+        ROWS scan, so we never have to think about these things again.
+        '''
+        if self.diode_orientation == DiodeOrientation.ROWS:
+            return matrix
+
+        return [
+            [col[col_entry] for col in matrix]
+            for col_entry in range(max(len(col) for col in matrix))
+        ]
+
+    def raw_scan(self):
+        matrix = []
+
+        for opin in self.outputs:
+            opin.value = True
+            matrix.append([ipin.value for ipin in self.inputs])
+            opin.value = False
+
+        return self._normalize_matrix(matrix)

kmk/circuitpython/util.py

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+import board
+import digitalio
+import time
+import sys
+
+
+def feather_signal_error_with_led_flash(rate=0.5):
+    '''
+    Flash the red LED for 10 seconds, alternating every $rate
+    Could be useful as an uncaught exception handler later on,
+    but is for now unused
+    '''
+
+    rled = digitalio.DigitalInOut(board.LED1)
+    rled.direction = digitalio.Direction.OUTPUT
+
+    # blink for 5 seconds and exit
+    for cycle in range(10):
+        rled.value = cycle % 2
+        time.sleep(rate)
+
+    sys.exit(1)