1 files changed, 71 insertions, 0 deletions
diff --git a/keyboards/sol/common/knob_v2.c b/keyboards/sol/common/knob_v2.c
new file mode 100644
index 000000000..f22f7c5d8
--- /dev/null
+++ b/keyboards/sol/common/knob_v2.c
@@ -0,0 +1,71 @@
+#include "knob_v2.h"
+
+bool knob_prev_a = false;
+static knob_report_t knob_report = {.dir = 0, .phase = 0};
+
+void knob_init(void) {
+    // I use pins D1 (ISR1) & D4 for a knob.
+
+    // Set pin mode for D4 as input.
+    DDRD &= ~(0UL << ENCODER_PIN_2);
+
+    // Enable internal pull-up for D4.
+    // This is done by "writing" 1 to a pin that has its mode set to input.
+    PORTD |= (1 << ENCODER_PIN_2);
+
+    // Enable interrupt for D1
+    // For more info on the below flags see this awesome section 11.1 (pages 89-90) here:
+    // https://cdn-shop.adafruit.com/datasheets/atmel-7766-8-bit-avr-atmega16u4-32u4_datasheet.pdf
+    // Set pin mode & pull-up.
+    DDRD &= ~(0UL << ENCODER_PIN_1);
+    PORTD |= (1UL << ENCODER_PIN_1);
+
+    // INT:    33221100
+    EICRA |= 0b00010000;  // 0b01 - any edge
+    // INT:     6  3210
+    EIMSK |= 0b00000100;
+}
+
+ISR(ENCODER_INT) {
+    bool a = PIND & (1 << ENCODER_PIN_1);
+
+    if (knob_prev_a != a) {
+        // "A" channel has REALLY changed.
+        knob_report.phase = a;
+        knob_prev_a = a;
+        bool b = PIND & (1 << ENCODER_PIN_2);
+        if (a == b) {
+            // Halfway through CCW rotation (A == B)
+            //
+            //         +---YOU ARE HERE (A=1, B=1)
+            //         |     +---OR HERE (A=0, B=0)
+            //         |     |
+            //         v     v
+            // A: _____/^^^^^\__
+            // B: __/^^^^^\_____
+            knob_report.dir++;
+        } else {
+            // Halfway through CW rotation (A != B)
+            //
+            //         +---YOU ARE HERE (A=1, B=0)
+            //         |     +---OR HERE (A=0, B=1)
+            //         |     |
+            //         v     v
+            // A: _____/^^^^^\_____
+            // B: ________/^^^^^\__
+            knob_report.dir--;
+        }
+    }
+}
+
+knob_report_t knob_report_read(void) {
+    // Return knob report.
+    return knob_report;
+}
+
+void knob_report_reset(void) {
+    // Call this ASAP once you've processed the previous knob report.
+    // TODO: This should probably be called within `knob_report_read`.
+    knob_report.dir = 0;
+    knob_report.phase = 0;
+}