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