lotus: Further adapt custom matrix scanning code

Following instructions here: https://docs.qmk.fm/#/custom_matrix
And looking at other keyboards.

Signed-off-by: Daniel Schaefer <dhs@frame.work>

keyboards/lotus/keymaps/default/keymap.c

@@ -60,76 +60,3 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,          BL_TOGG,                            KC_TRNS, KC_TRNS, KC_HOME, KC_PGDN, KC_PGUP, KC_RGHT
     )
 };
-
-/**
- * Keyscan mockup/pseudo-code below. Prefixed with zoid_ to avoid hooking into system
-*/
-#define LOTUS_COLS 14
-
-void adc_gpio_init(int gpio) {
-    // TODO: Implement
-}
-void adc_select_input(int adc_channel) {
-    // TODO: Implement
-}
-
-// Mux GPIOs
-#define MUX_A 1
-#define MUX_B 2
-#define MUX_C 3
-#define MUX_ENABLE 4
-// Mux output
-#define ADC_IN 28
-
-void gpio_set(int gpio, int enable) {
-    // TODO: Implement
-}
-
-/**
- * Tell the mux to select a specific column
- *
- * Splits the positive integer (<=7) into its three component bits.
-*/
-void mux_select_col(int col) {
-    int bits[] = {
-        (col & 0x1) > 0,
-        (col & 0x4) > 0,
-        (col & 0x8) > 0
-    };
-    gpio_set(MUX_A, bits[0]);
-    gpio_set(MUX_B, bits[1]);
-    gpio_set(MUX_C, bits[2]);
-}
-uint16_t adc_read(void) { return 0; }
-
-void zoid_keyscan(void) {
-    for (int col = 0; col < LOTUS_COLS; col++) {
-        // TODO: Map col index to GPIO
-        // Drive column high so we can measure the resistors
-        gpio_set(col, 1);
-
-        // Read ADC for this row
-        mux_select_col(col);
-        uint16_t adc_value = adc_read();
-
-        // Interpret ADC value as rows
-        printf("%04X", adc_value);
-
-        // Drive column low again
-        gpio_set(col, 1);
-    }
-}
-
-void adc_init(void) {
-    gpio_set(MUX_ENABLE, 1);
-}
-// TODO: Do we need a de-init? Probably not.
-
-void zoid_keyscan_init(void) {
-    adc_init();
-
-    // Make sure GPIO is high-impedance, no pullups etc
-    adc_gpio_init(26);
-    // Select ADC input 0 (GPIO26)
-    adc_select_input(0);
-}

keyboards/lotus/matrix.c

@@ -0,0 +1,114 @@
+
+#include <stdio.h>
+#include <stdint.h>
+#include "debug.h"
+#include "matrix.h"
+#include "print.h"
+#include "quantum.h"
+
+#define LOTUS_COLS 14
+
+/**
+ * Tell RP2040 ADC controller to initialize a specific GPIO for ADC input
+*/
+void adc_gpio_init(int gpio) {
+    assert(gpio >= 26 && gpio <= 29);
+    // TODO: Implement
+}
+
+/**
+ * Tell RP2040 ADC controller to read from a specific ADC channel
+*/
+void adc_select_input(int adc_channel) {
+    assert(adc_channel >= 0 && adc_channel <= 4);
+    // TODO: Implement
+}
+
+// Mux GPIOs
+#define MUX_A 1
+#define MUX_B 2
+#define MUX_C 3
+#define MUX_ENABLE 4
+// Mux output
+#define ADC_IN 28
+
+/**
+ * Tell the mux to select a specific column
+ * 
+ * Splits the positive integer (<=7) into its three component bits.
+*/
+static void mux_select_col(int col) {
+    int bits[] = {
+        (col & 0x1) > 0,
+        (col & 0x4) > 0,
+        (col & 0x8) > 0
+    };
+    writePin(MUX_A, bits[0]);
+    writePin(MUX_B, bits[1]);
+    writePin(MUX_C, bits[2]);
+}
+static uint16_t adc_read(void) { return 0; }
+
+/**
+ * Based on the adc value, update the matrix for this column
+ * */
+static bool interpret_adc_col(matrix_row_t cur_matrix[], uint16_t adc_value, int col) {
+    bool changed = false;
+
+    printf("Col %d - ADC value:%04X", col, adc_value);
+    for(uint8_t row = 0; row < MATRIX_ROWS; row++) {
+        // TODO: Decode adc_value and set each row in this column
+        uint8_t key_state = 0;
+
+        cur_matrix[row] |= key_state ? 0 : (1 << col);
+    }
+
+    return changed;
+}
+
+/**
+ * Overriding behavior of matrix_scan from quantum/matrix.c
+*/
+bool matrix_scan_custom(matrix_row_t current_matrix[]) {
+    bool changed = false;
+
+    for (int col = 0; col < LOTUS_COLS; col++) {
+        // TODO: Map col index to GPIO
+        // Drive column high so we can measure the resistors
+        writePinHigh(col);
+        wait_us(30); // Probably good idea to wait a bit
+
+        // Read ADC for this row
+        mux_select_col(col);
+        uint16_t adc_value = adc_read();
+
+        // Interpret ADC value as rows
+        changed |= interpret_adc_col(current_matrix, adc_value, col);
+
+        // Drive column low again
+        writePinLow(col);
+    }
+
+    return changed;
+}
+
+/**
+ * Enable the ADC MUX
+ * 
+ * TODO: Do we need a de-init? Probably not.
+*/
+static void adc_mux_init(void) {
+    writePinHigh(MUX_ENABLE);
+}
+
+/**
+ * Overriding behavior of matrix_init from quantum/matrix.c
+*/
+void matrix_init_custom(void) {
+    adc_mux_init();
+
+    // Make sure GPIO is high-impedance, no pullups etc
+    adc_gpio_init(26);
+    // Select ADC input 0 (GPIO26)
+    adc_select_input(0);
+}

keyboards/lotus/rules.mk

@@ -2,3 +2,7 @@ WS2812_DRIVER = vendor
 SERIAL_DRIVER = vendor
 #RGB_MATRIX_ENABLE = false
 RGB_MATRIX_DRIVER = IS31FL3745
+
+# Custom matrix scanning code via ADC
+#CUSTOM_MATRIX = lite
+#SRC += matrix.c