Add SN74x154 driver and convert AL1 custom matrix (#16331)

3 files changed, 88 insertions, 72 deletions

diff --git a/keyboards/al1/config.h b/keyboards/al1/config.h
index c8edb8ebfe..570eb03ae2 100644
--- a/keyboards/al1/config.h
+++ b/keyboards/al1/config.h
@@ -30,6 +30,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define MATRIX_ROWS 6
 #define MATRIX_COLS 16
 
+#define MATRIX_ROW_PINS { C7, B1, B2, C6, B4, B5 }
+
+#define SN74X154_ADDRESS_PINS { D4, D5, D6, D7 }
+#define SN74X154_E1_PIN D3
+
 #define LED_NUM_LOCK_PIN D0
 #define LED_CAPS_LOCK_PIN B7
 #define LED_SCROLL_LOCK_PIN D1
diff --git a/keyboards/al1/matrix.c b/keyboards/al1/matrix.c
index 1407cbc089..e3d7971f1c 100644
--- a/keyboards/al1/matrix.c
+++ b/keyboards/al1/matrix.c
@@ -1,91 +1,101 @@
-#include "matrix.h"
+/* Copyright 2022
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
 
+#include "matrix.h"
 #include "gpio.h"
+#include "sn74x154.h"
 
-static uint8_t read_rows(void) {
-    return (readPin(C7) ? 0 : 1) |
-           (readPin(B1) ? 0 : 2) |
-           (readPin(B2) ? 0 : 4) |
-           (readPin(C6) ? 0 : 8) |
-           (readPin(B4) ? 0 : 16) |
-           (readPin(B5) ? 0 : 32);
-}
+static const pin_t row_pins[MATRIX_ROWS] = MATRIX_ROW_PINS;
 
+/* All columns use a 74HC154 4-to-16 demultiplexer.
+ * D3 is the enable pin, must be set high to use it.
+ *
+ *     A3   A2   A1   A0
+ *     D7   D6   D5   D4
+ * 0:   0    0    0    0
+ * 1:   0    0    0    1
+ * 2:   0    0    1    0
+ * 3:   0    0    1    1
+ * 4:   0    1    0    0
+ * 5:   0    1    0    1
+ * 6:   0    1    1    0
+ * 7:   0    1    1    1
+ * 8:   1    0    0    0
+ * 9:   1    0    0    1
+ * 10:  1    0    1    0
+ * 11:  1    0    1    1
+ * 12:  1    1    0    0
+ * 13:  1    1    0    1
+ * 14:  1    1    1    0
+ * 15:  1    1    1    1
+ */
 static void select_col(uint8_t col) {
-    writePinLow(D3);
-
-    writePin(D4, (col & 1));
-    writePin(D5, (col & 2));
-    writePin(D6, (col & 4));
-    writePin(D7, (col & 8));
+    sn74x154_set_addr(col);
 }
 
-static void  unselect_cols(void) {
-    writePinHigh(D3);
+static void init_pins(void) {
+    for (uint8_t x = 0; x < MATRIX_ROWS; x++) {
+        setPinInputHigh(row_pins[x]);
+    }
 }
 
-void matrix_init_custom(void) {
-    /* 74HC154 col pin configuration
-     * pin:     D3  D7  D6  D5  D4
-     * row: off  0   x   x   x   x
-     *      0    1   0   0   0   0
-     *      1    1   0   0   0   1
-     *      2    1   0   0   1   0
-     *      3    1   0   0   1   1
-     *      4    1   0   1   0   0
-     *      5    1   0   1   0   1
-     *      6    1   0   1   1   0
-     *      7    1   0   1   1   1
-     *      8    1   1   0   0   0
-     *      9    1   1   0   0   1
-     *      10   1   1   0   1   0
-     *      11   1   1   0   1   1
-     *      12   1   1   1   0   0
-     *      13   1   1   1   0   1
-     *      14   1   1   1   1   0
-     *      15   1   1   1   1   1
-     */
-    setPinOutput(D3);
-    writePinHigh(D3);
+static bool read_rows_on_col(matrix_row_t current_matrix[], uint8_t current_col) {
+    bool matrix_changed = false;
+
+    // Select col and wait for col seleciton to stabilize
+    select_col(current_col);
+    matrix_io_delay();
 
-    setPinOutput(D4);
-    setPinOutput(D5);
-    setPinOutput(D6);
-    setPinOutput(D7);
+    // For each row...
+    for (uint8_t row_index = 0; row_index < MATRIX_ROWS; row_index++) {
+        // Store last value of row prior to reading
+        matrix_row_t last_row_value = current_matrix[row_index];
 
+        // Check row pin state
+        if (readPin(row_pins[row_index]) == 0) {
+            // Pin LO, set col bit
+            current_matrix[row_index] |= (MATRIX_ROW_SHIFTER << current_col);
+        } else {
+            // Pin HI, clear col bit
+            current_matrix[row_index] &= ~(MATRIX_ROW_SHIFTER << current_col);
+        }
 
-    /* Row pin configuration
-     *
-     * row:  0  1  2  3  4  5
-     * pin: C7 B1 B2 C6 B4 B5
-     *
-     */
-    setPinInputHigh(C7);
-    setPinInputHigh(B1);
-    setPinInputHigh(B2);
-    setPinInputHigh(C6);
-    setPinInputHigh(B4);
-    setPinInputHigh(B5);
+        // Determine if the matrix changed state
+        if ((last_row_value != current_matrix[row_index]) && !(matrix_changed)) {
+            matrix_changed = true;
+        }
+    }
+
+    return matrix_changed;
+}
+
+void matrix_init_custom(void) {
+    // initialize demultiplexer
+    sn74x154_init();
+    sn74x154_set_enabled(true);
+    // initialize key pins
+    init_pins();
 }
 
 bool matrix_scan_custom(matrix_row_t current_matrix[]) {
     bool changed = false;
 
-    for (uint8_t col = 0; col < MATRIX_COLS; col++) {
-        select_col(col);
-        matrix_io_delay();
-        uint8_t rows = read_rows();
-
-        for (uint8_t row = 0; row < MATRIX_ROWS; row++) {
-            bool prev_bit = current_matrix[row] & ((matrix_row_t)1 << col);
-            bool curr_bit = rows & (1 << row);
-
-            if (prev_bit != curr_bit) {
-                current_matrix[row] ^= ((matrix_row_t)1 << col);
-                changed = true;
-            }
-        }
-        unselect_cols();
+    // Set col, read rows
+    for (uint8_t current_col = 0; current_col < MATRIX_COLS; current_col++) {
+        changed |= read_rows_on_col(current_matrix, current_col);
     }
 
     return changed;
diff --git a/keyboards/al1/rules.mk b/keyboards/al1/rules.mk
index 670712f661..1f8e81de20 100644
--- a/keyboards/al1/rules.mk
+++ b/keyboards/al1/rules.mk
@@ -18,4 +18,5 @@ RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
 AUDIO_ENABLE = no           # Audio output
 
 CUSTOM_MATRIX = lite
-SRC += matrix.c
+VPATH += drivers/gpio
+SRC += matrix.c sn74x154.c