56 lines
1.8 KiB
Markdown
56 lines
1.8 KiB
Markdown
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# Scanners
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Smaller boards and macro pads sometimes assign a GPIO pin to each key, rather
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than using a full matrix. Boards like this aren't compatible with the default
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matrix scanner, so you will need to swap it out with an alternative scanner.
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Beside the default `Matrix` scanner, KMK includes the following:
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## keypad.Keys
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The `keypad.Keys` scanner treats individual GPIO pins as discrete keys. To use
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this scanner, provide a sequence of pins that describes the layout of your
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board then include it in the initialisation sequence of your keyboard class.
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```python
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import board
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from kmk.kmk_keyboard import KMKKeyboard
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from kmk.scanners.native_keypad_scanner import keys_scanner
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# GPIO to key mapping - each line is a new row.
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_KEY_CFG = [
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[board.SW3, board.SW7, board.SW11, board.SW15],
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[board.SW2, board.SW6, board.SW10, board.SW14],
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[board.SW1, board.SW5, board.SW9, board.SW13],
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[board.SW0, board.SW4, board.SW8, board.SW12],
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]
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# Keyboard implementation class
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class MyKeyboard(KMKKeyboard):
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def __init__(self):
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# create and register the scanner
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self.matrix = keys_scanner(_KEY_CFG)
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```
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## keypad.KeyMatrix
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The `keypad.KeyMatrix` scanner is an alternative implementation of the default
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matrix scanner using CircuitPython's builtin keypad objects. This is currently
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experimental and ***not recommended for use***.
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Using this scanner is similar to the `keypad.Keys` scanner. Create the scanner
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using `keypad_matrix()` instead of `keys_scanner()`.
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## `Scanner` base class
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If you require a different type of scanner, you can create your own by
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providing a subclass of `Scanner`. This is a very simple interface, it only
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contains a single method, `scan_for_changes(self)` which returns a key report
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if one exists, or `None` otherwise.
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