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#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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#include <avr/sleep.h> // Required for sleep modes
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#include <stdint.h> // For standard integer types, e.g., uint8_t
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// --- Pin Definitions ---
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#define TX_PIN PIN6_bm // PA6 for transmission
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#define CLK_PIN PIN7_bm // PA7 for rotary encoder clock (interrupt)
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#define DT_PIN PIN1_bm // PA1 for rotary encoder data
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#define SW_PIN PIN2_bm // PA2 for rotary encoder switch (interrupt)
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// --- Task Queue Configuration ---
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#define BUFFER_SIZE 8 // Size of the circular buffer for tasks
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// --- Event Types (messages to be stored in the queue) ---
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typedef enum {
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NO_EVENT = 0,
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ENCODER_RIGHT = 0x01, // Example value for right turn
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ENCODER_LEFT = 0x02, // Example value for left turn
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BUTTON_PRESS = 0x04 // Example value for button press
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} EventType;
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// --- Task Queue Variables ---
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volatile EventType taskQueue[BUFFER_SIZE]; // Array for the task queue
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volatile uint8_t queueHead = 0; // Index for adding new tasks
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volatile uint8_t queueTail = 0; // Index for removing tasks
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// --- Function to add a task to the queue ---
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void enqueue_task(EventType event) {
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uint8_t nextHead = (queueHead + 1) % BUFFER_SIZE;
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// Check if queue is not full before enqueuing
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if (nextHead != queueTail) {
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taskQueue[queueHead] = event;
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queueHead = nextHead;
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}
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}
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// --- Function to remove a task from the queue ---
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EventType dequeue_task() {
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// Check if queue is empty
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if (queueHead == queueTail) {
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return NO_EVENT;
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}
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EventType event = taskQueue[queueTail];
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queueTail = (queueTail + 1) % BUFFER_SIZE;
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return event;
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}
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// --- Transmission Functions (approx. 5kbps) ---
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// For 5kbps, each bit duration is 1 / 5000 Hz = 200 us.
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// Adjust BIT_DURATION_US empirically for accurate timing if needed.
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#define BIT_DURATION_US 193 // Adjusted for potential instruction overhead
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void send_bit(uint8_t bit) {
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if (bit) {
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PORTA.OUTSET = TX_PIN; // High (Transmitter ON)
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} else {
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PORTA.OUTCLR = TX_PIN; // Low (Transmitter OFF)
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}
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_delay_us(BIT_DURATION_US);
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}
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void send_byte(uint8_t data) {
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// Start bit (active low, so 0)
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send_bit(0);
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// Data bits (LSB first)
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for (uint8_t i = 0; i < 8; i++) {
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send_bit(data & 0x01);
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data >>= 1;
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}
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// Stop bit (active high, so 1)
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send_bit(1);
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}
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// --- Interrupt Service Routine for PORTA Pin Change Interrupts ---
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ISR(PORTA_PORT_vect) {
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// Clear the interrupt flags for the pins that caused the interrupt.
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// This is crucial to prevent re-triggering immediately.
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if (PORTA.INTFLAGS & CLK_PIN) {
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PORTA.INTFLAGS = CLK_PIN; // Clear CLK_PIN's interrupt flag
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// Read DT_PIN to determine direction
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if (PORTA.IN & DT_PIN) {
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// DT_PIN is HIGH when CLK_PIN goes HIGH -> Counter-clockwise (Left)
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enqueue_task(ENCODER_LEFT);
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} else {
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// DT_PIN is LOW when CLK_PIN goes HIGH -> Clockwise (Right)
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enqueue_task(ENCODER_RIGHT);
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}
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}
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if (PORTA.INTFLAGS & SW_PIN) {
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PORTA.INTFLAGS = SW_PIN; // Clear SW_PIN's interrupt flag
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// Enqueue button press. Consider debouncing for real-world buttons.
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enqueue_task(BUTTON_PRESS);
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}
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}
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// --- Setup Function ---
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void setup() {
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// Configure TX_PIN (PA6) as output
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PORTA.DIRSET = TX_PIN; // Define PA6 as output
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PORTA.OUTCLR = TX_PIN; // Set initial value of PA6 to 0 (OFF)
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// Configure CLK_PIN (PA7), DT_PIN (PA1), SW_PIN (PA2) as inputs
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PORTA.DIRCLR = CLK_PIN;
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PORTA.DIRCLR = DT_PIN;
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PORTA.DIRCLR = SW_PIN;
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// Configure interrupts for CLK_PIN (PA7) and SW_PIN (PA2) on rising edge
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// Make sure these are the correct bits for your specific AVR family (e.g., tinyAVR 0/1/2-series, megaAVR)
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PORTA.PIN7CTRL |= PORT_ISC_RISING_gc; // CLK_PIN interrupt on rising edge
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PORTA.PIN2CTRL |= PORT_ISC_RISING_gc; // SW_PIN interrupt on rising edge
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// Set the sleep mode to POWER_DOWN for maximum power saving.
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// The device will wake up on any enabled interrupt.
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set_sleep_mode(SLEEP_MODE_PWR_DOWN);
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// Enable global interrupts
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sei();
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}
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// --- Main Loop ---
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void loop() {
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// First, check if there are any events to process before going to sleep.
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// This prevents the system from sleeping if an event arrived just before `sleep_mode()`.
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cli(); // Disable interrupts while checking/modifying the queue
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if (queueHead != queueTail) { // If the queue is not empty
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EventType currentEvent = dequeue_task();
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sei(); // Re-enable interrupts
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// Transmit the event. Keep interrupts disabled during transmission
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// to ensure accurate bit timing.
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cli();
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send_byte((uint8_t)currentEvent);
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sei();
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} else {
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// If the queue is empty, enable interrupts, and go to sleep.
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// The MCU will wake up on any enabled interrupt (CLK_PIN or SW_PIN).
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// Interrupts must be enabled *before* calling sleep_mode().
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sei();
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sleep_mode(); // Go to selected sleep mode
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// Execution resumes here after an interrupt wakes the MCU
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}
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// After waking up or processing an event, the loop continues to check the queue again.
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// If there were multiple events queued, it will process them one by one.
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}
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RigolDS0.png
(77 KB)
RigolDS1.png
(73 KB)
RigolDS2.png
(75 KB)
DebounceCircuit.jpeg
(33 KB)
