fix: Add delay to DemuxKeyMatrix along with columns_to_anodes and transpose options

ports/espressif/boards/m5stack_cardputer/cardputer_keyboard.c

@@ -110,6 +110,8 @@ void cardputer_keyboard_init(void) {
         row_addr_pins,           // row_addr_pins
         7,                       // num_column_pins
         column_pins,             // column_pins
+        true,                    // columns_to_anodes
+        false,                   // transpose
         0.01f,                   // interval
         20,                      // max_events
         2                        // debounce_threshold

shared-bindings/keypad_demux/DemuxKeyMatrix.c

@@ -36,6 +36,8 @@
 //|         self,
 //|         row_addr_pins: Sequence[microcontroller.Pin],
 //|         column_pins: Sequence[microcontroller.Pin],
+//|         columns_to_anodes: bool = True,
+//|         transpose: bool = False,
 //|         interval: float = 0.020,
 //|         max_events: int = 64,
 //|         debounce_threshold: int = 1,
@@ -51,7 +53,18 @@
 //|         An `keypad.EventQueue` is created when this object is created and is available in the `events` attribute.
 //|
 //|         :param Sequence[microcontroller.Pin] row_addr_pins: The pins attached to the rows demultiplexer.
+//|           If your columns are multiplexed, set ``transpose`` to ``True``.
 //|         :param Sequence[microcontroller.Pin] column_pins: The pins attached to the columns.
+//|         :param bool columns_to_anodes: Default ``True``.
+//|           If the matrix uses diodes, the diode anodes are typically connected to the column pins
+//|           with the cathodes connected to the row pins.  This implies an inverting multiplexer that drives
+//|           the selected row pin low.  If your diodes are reversed, with a non-inverting multiplexer
+//|           that drives the selected row high, set ``columns_to_anodes`` to ``False``.
+//|           If ``transpose`` is ``True`` the sense of columns and rows are reversed here.
+//|         :param bool transpose: Default ``False``.
+//|           If your matrix is multiplexed on columns rather than rows, set ``transpose`` to ``True``.
+//|           This swaps the meaning of ``row_addr_pins`` to ``column_addr_pins``;
+//|           ``column_pins`` to ``row_pins``; and ``columns_to_anodes`` to ``rows_to_anodes``.
 //|         :param float interval: Scan keys no more often than ``interval`` to allow for debouncing.
 //|           ``interval`` is in float seconds. The default is 0.020 (20 msecs).
 //|         :param int max_events: maximum size of `events` `keypad.EventQueue`:
@@ -67,10 +80,12 @@
 
 static mp_obj_t keypad_demux_demuxkeymatrix_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
     keypad_demux_demuxkeymatrix_obj_t *self = mp_obj_malloc(keypad_demux_demuxkeymatrix_obj_t, &keypad_demux_demuxkeymatrix_type);
-    enum { ARG_row_addr_pins, ARG_column_pins, ARG_interval, ARG_max_events, ARG_debounce_threshold };
+    enum { ARG_row_addr_pins, ARG_column_pins, ARG_columns_to_anodes, ARG_transpose, ARG_interval, ARG_max_events, ARG_debounce_threshold };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_row_addr_pins, MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_column_pins, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_columns_to_anodes, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
+        { MP_QSTR_transpose, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
         { MP_QSTR_interval, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_max_events, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 64} },
         { MP_QSTR_debounce_threshold, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1} },
@@ -107,7 +122,7 @@ static mp_obj_t keypad_demux_demuxkeymatrix_make_new(const mp_obj_type_t *type,
         column_pins_array[column] = pin;
     }
 
-    common_hal_keypad_demux_demuxkeymatrix_construct(self, num_row_addr_pins, row_addr_pins_array, num_column_pins, column_pins_array, interval, max_events, debounce_threshold);
+    common_hal_keypad_demux_demuxkeymatrix_construct(self, num_row_addr_pins, row_addr_pins_array, num_column_pins, column_pins_array, args[ARG_columns_to_anodes].u_bool, args[ARG_transpose].u_bool, interval, max_events, debounce_threshold);
     return MP_OBJ_FROM_PTR(self);
 }
 

shared-bindings/keypad_demux/DemuxKeyMatrix.h

@@ -11,7 +11,7 @@
 
 extern const mp_obj_type_t keypad_demux_demuxkeymatrix_type;
 
-void common_hal_keypad_demux_demuxkeymatrix_construct(keypad_demux_demuxkeymatrix_obj_t *self, mp_uint_t num_row_addr_pins, const mcu_pin_obj_t *row_addr_pins[], mp_uint_t num_column_pins, const mcu_pin_obj_t *column_pins[], mp_float_t interval, size_t max_events, uint8_t debounce_threshold);
+void common_hal_keypad_demux_demuxkeymatrix_construct(keypad_demux_demuxkeymatrix_obj_t *self, mp_uint_t num_row_addr_pins, const mcu_pin_obj_t *row_addr_pins[], mp_uint_t num_column_pins, const mcu_pin_obj_t *column_pins[], bool columns_to_anodes, bool transpose, mp_float_t interval, size_t max_events, uint8_t debounce_threshold);
 
 void common_hal_keypad_demux_demuxkeymatrix_deinit(keypad_demux_demuxkeymatrix_obj_t *self);
 

shared-bindings/keypad_demux/__init__.c

@@ -11,8 +11,14 @@
 
 //| """Support for scanning key matrices that use a demultiplexer
 //|
-//| The `keypad_demux` module provides native support to scan sets of keys or buttons,
-//| connected in a row-and-column matrix.
+//| The `keypad_demux` module provides native support to scan a matrix of keys or buttons
+//| where either the row or column axis is controlled by a demultiplexer or decoder IC
+//| such as the 74LS138 or 74LS238.  In this arrangement a binary input value
+//| determines which column (or row) to select, thereby reducing the number of input pins.
+//| For example the input 101 would select line 5 in the matrix.
+//| Set ``columns_to_anodes`` to ``False`` with a non-inverting demultiplexer
+//| which drives the selected line high.
+//| Set ``transpose`` to ``True`` if columns are multiplexed rather than rows.
 //|
 //| .. jinja
 //| """

shared-module/keypad_demux/DemuxKeyMatrix.c

@@ -7,6 +7,7 @@
 #include <string.h>
 
 #include "py/gc.h"
+#include "py/mphal.h"
 #include "py/runtime.h"
 #include "shared-bindings/digitalio/DigitalInOut.h"
 #include "shared-bindings/keypad/EventQueue.h"
@@ -26,11 +27,15 @@ static keypad_scanner_funcs_t keymatrix_funcs = {
 };
 
 static mp_uint_t row_column_to_key_number(keypad_demux_demuxkeymatrix_obj_t *self, mp_uint_t row, mp_uint_t column) {
-    return row * self->column_digitalinouts->len + column;
+    // return the key index in the user's coordinate system
+    return row * common_hal_keypad_demux_demuxkeymatrix_get_column_count(self) + column;
 }
 
-void common_hal_keypad_demux_demuxkeymatrix_construct(keypad_demux_demuxkeymatrix_obj_t *self, mp_uint_t num_row_addr_pins, const mcu_pin_obj_t *row_addr_pins[], mp_uint_t num_column_pins, const mcu_pin_obj_t *column_pins[], mp_float_t interval, size_t max_events, uint8_t debounce_threshold) {
+void common_hal_keypad_demux_demuxkeymatrix_construct(keypad_demux_demuxkeymatrix_obj_t *self, mp_uint_t num_row_addr_pins, const mcu_pin_obj_t *row_addr_pins[], mp_uint_t num_column_pins, const mcu_pin_obj_t *column_pins[], bool columns_to_anodes, bool transpose, mp_float_t interval, size_t max_events, uint8_t debounce_threshold) {
 
+    // the multiplexed pins are outputs so we can set the address for the target row
+    // the sense of the address pins themselves doesn't change with columns_to_anodes
+    // but the value output on the selected row line will be !columns_to_anodes
     mp_obj_t row_addr_dios[num_row_addr_pins];
     for (size_t row = 0; row < num_row_addr_pins; row++) {
         digitalio_digitalinout_obj_t *dio =
@@ -41,17 +46,20 @@ void common_hal_keypad_demux_demuxkeymatrix_construct(keypad_demux_demuxkeymatri
     }
     self->row_addr_digitalinouts = mp_obj_new_tuple(num_row_addr_pins, row_addr_dios);
 
+    // the column pins are always inputs, with default state based on columns_to_anodes
     mp_obj_t column_dios[num_column_pins];
     for (size_t column = 0; column < num_column_pins; column++) {
         digitalio_digitalinout_obj_t *dio =
             mp_obj_malloc(digitalio_digitalinout_obj_t, &digitalio_digitalinout_type);
         dio->base.type = &digitalio_digitalinout_type;
         common_hal_digitalio_digitalinout_construct(dio, column_pins[column]);
-        common_hal_digitalio_digitalinout_switch_to_input(dio, PULL_UP);
+        common_hal_digitalio_digitalinout_switch_to_input(dio, columns_to_anodes ? PULL_UP : PULL_DOWN);
         column_dios[column] = dio;
     }
     self->column_digitalinouts = mp_obj_new_tuple(num_column_pins, column_dios);
 
+    self->columns_to_anodes = columns_to_anodes;
+    self->transpose = transpose;
     self->funcs = &keymatrix_funcs;
 
     keypad_construct_common((keypad_scanner_obj_t *)self, interval, max_events, debounce_threshold);
@@ -78,11 +86,15 @@ void common_hal_keypad_demux_demuxkeymatrix_deinit(keypad_demux_demuxkeymatrix_o
 }
 
 size_t common_hal_keypad_demux_demuxkeymatrix_get_row_count(keypad_demux_demuxkeymatrix_obj_t *self) {
-    return 1 << self->row_addr_digitalinouts->len;
+    return self->transpose
+        ? self->column_digitalinouts->len
+        : (size_t)(1 << self->row_addr_digitalinouts->len);
 }
 
 size_t common_hal_keypad_demux_demuxkeymatrix_get_column_count(keypad_demux_demuxkeymatrix_obj_t *self) {
-    return self->column_digitalinouts->len;
+    return self->transpose
+        ? (size_t)(1 << self->row_addr_digitalinouts->len)
+        : self->column_digitalinouts->len;
 }
 
 mp_uint_t common_hal_keypad_demux_demuxkeymatrix_row_column_to_key_number(keypad_demux_demuxkeymatrix_obj_t *self, mp_uint_t row, mp_uint_t column) {
@@ -102,22 +114,38 @@ static size_t demuxkeymatrix_get_key_count(void *self_in) {
 
 static void demuxkeymatrix_scan_now(void *self_in, mp_obj_t timestamp) {
     keypad_demux_demuxkeymatrix_obj_t *self = self_in;
-
-    for (size_t row = 0; row < common_hal_keypad_demux_demuxkeymatrix_get_row_count(self); row++) {
-        // Set the row address on demultiplexer
+    // We always scan through the multiplexed lines using the array sizes directly
+    // and apply transposition only when translating to key number.
+    for (int row = 0; row < (1 << self->row_addr_digitalinouts->len); row++) {
+        // Set the row address on the demultiplexer.
+        // When columns_to_anodes is True (default) we've got an inverting demux
+        // so the selected line is pulled low, and we look for rows that get pulled low.
+        // When columns_to_anodes is False we do the reverse.
         size_t mask = 0b00000001;
         for (size_t row_addr_pin = 0; row_addr_pin < self->row_addr_digitalinouts->len; row_addr_pin++) {
             digitalio_digitalinout_obj_t *dio = self->row_addr_digitalinouts->items[row_addr_pin];
             common_hal_digitalio_digitalinout_set_value(dio, (mask & row) != 0);
             mask = mask << 1;
         }
 
-        for (size_t column = 0; column < common_hal_keypad_demux_demuxkeymatrix_get_column_count(self); column++) {
-            mp_uint_t key_number = row_column_to_key_number(self, row, column);
-
-            // Get the current state, by reading whether the column got pulled to the row value or not.
-            // If low, the key is pressed.
-            const bool current = !common_hal_digitalio_digitalinout_get_value(self->column_digitalinouts->items[column]);
+        // Wait a moment to let the columns settle.
+        // The normal KeyMatrix uses a 1us delay but that still gave echoes on my
+        // nullbitsco nibble 65% (16 x 5 matrix).  For example when key (row, col) is pressed
+        // both (row, col) and (row+1, col) (and sometimes row+2) are registered,
+        // especially when row+1 is a power of 2 (all mux bits change) and col is 0.
+        // The QMK implementation for this keyboard uses a 5us delay which works here too
+        mp_hal_delay_us(5);
+
+        for (size_t column = 0; column < self->column_digitalinouts->len; column++) {
+            mp_uint_t key_number = self->transpose
+                ? row_column_to_key_number(self, column, row)
+                : row_column_to_key_number(self, row, column);
+
+            // Get the current state, by reading whether the column got pulled to the row value or not,
+            // which is the opposite of columns_to_anodes.
+            const bool current =
+                common_hal_digitalio_digitalinout_get_value(self->column_digitalinouts->items[column]) !=
+                self->columns_to_anodes;
 
             // Record any transitions.
             if (keypad_debounce((keypad_scanner_obj_t *)self, key_number, current)) {

shared-module/keypad_demux/DemuxKeyMatrix.h

@@ -17,6 +17,8 @@ typedef struct {
     KEYPAD_SCANNER_COMMON_FIELDS;
     mp_obj_tuple_t *row_addr_digitalinouts;
     mp_obj_tuple_t *column_digitalinouts;
+    bool columns_to_anodes;
+    bool transpose;
 } keypad_demux_demuxkeymatrix_obj_t;
 
 void keypad_demux_demuxkeymatrix_scan(keypad_demux_demuxkeymatrix_obj_t *self);