Initial

74C922.c

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+#include "config.h"
+#include <avr/io.h>
+#include <util/delay.h>
+#include <stdbool.h>
+
+// Pin Definitions
+#define ENCODER_A_PIN       PD6
+#define ENCODER_B_PIN       PD5
+#define ENCODER_C_PIN       PD4
+#define ENCODER_D_PIN       PD3
+#define ENCODER_OE_PIN      PD2
+#define ENCODER_DA_PIN      PD1
+
+void prepare_interrupt() {
+	EICRA |= (1 << ISC00); // Any logical change triggers interrupt
+	EIMSK |= (1 << INT0); // INT0 external interrupt
+	PCICR |= (1 << PCIE0);
+}
+
+// Encoder Module
+void encoder_init() {
+	// Set A, B, C, D, and DA pins as inputs
+	DDRD &= ~((1 << ENCODER_A_PIN) | (1 << ENCODER_B_PIN) | (1 << ENCODER_C_PIN) | (1 << ENCODER_D_PIN) | (1 << ENCODER_DA_PIN));
+	
+	// Set OE as output
+	DDRD |= (1 << ENCODER_OE_PIN);
+	
+	// Enable internal pull-up resistors for A, B, C, D, and OE pins
+	PORTD |= (1 << ENCODER_A_PIN) | (1 << ENCODER_B_PIN) | (1 << ENCODER_C_PIN) | (1 << ENCODER_D_PIN) | (1 << ENCODER_DA_PIN);
+}
+
+uint8_t encoder_read() {
+	uint8_t encoder_data = 0;
+	
+	// Set OE (Output Enable) pin low to enable the encoder
+	PORTD &= ~(1 << ENCODER_OE_PIN);
+	_delay_us(1);
+
+	// Read the state of the encoder
+	encoder_data = PIND >> (ENCODER_A_PIN - 3);
+	encoder_data &= 0x0F;
+	
+	// Set OE pin high to disable the encoder
+	PORTD |= (1 << ENCODER_OE_PIN);
+	
+	return encoder_data;
+}
+
+bool encoder_available() {
+	return (PIND & (1 << ENCODER_DA_PIN));
+}

74C922.h

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+#ifndef H74C922_H
+#define H74C922_H
+
+void encoder_init();
+uint8_t encoder_read();
+bool encoder_available();
+
+#endif // 74C922_H

DHT22.c

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+#include "config.h"
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <stdbool.h>
+
+#include "GDM1602K.h"
+
+#define DATAPIN PC0
+#define PORT PORTC
+#define PIN PINC
+#define DDR DDRC
+
+bool is_high() {
+	return (PIN & (1 << DATAPIN));
+}
+
+// Function to read data from the DHT22 sensor
+int DHT22_Read(int *temperature, int *humidity)
+{
+	// Set the data pin as output
+	DDR |= (1 << DATAPIN);
+	PORT |= (1 << DATAPIN); // Set the pin high, if not already pulled up
+
+	_delay_ms(100);
+	
+	// Send start signal
+	PORT &= ~(1 << DATAPIN); // Set the pin low
+	_delay_us(500);       // Hold it for a while
+	PORT |= (1 << DATAPIN);  // Set the pin high
+	DDR &= ~(1 << DATAPIN); // Data direction in
+
+	_delay_us(20);       // Wait for 40 microseconds
+
+	// Sensor should have pulled low here
+	if(PIN & (1 << DATAPIN)) return -2;
+
+	_delay_us(80);       // Wait for 80 microseconds
+
+	// Sensor should have pulled high here
+	if(!(PIN & (1 << DATAPIN))) return -1;
+
+	// Read data from the sensor
+	uint8_t data[5] = {0, 0, 0, 0, 0};
+	uint8_t bitMask = 0x80; // All zeroes with MSB high
+	uint8_t byteIndex = 0;
+
+	for (byteIndex = 0; byteIndex < 5; byteIndex++)
+	{
+		for (bitMask = 0x80; bitMask != 0; bitMask >>= 1)
+		{
+			// Wait for the data bit to go low
+			while (!(PIN & (1 << PC0)))
+			;
+			
+			// Wait for the data bit to go high
+			_delay_us(20);
+			if (PIN & (1 << PC0))
+			data[byteIndex] |= bitMask;
+			
+			// Wait for the data bit to go low (end of bit)
+			while (PIN & (1 << PC0))
+			;
+		}
+	}
+
+	// Verify checksum
+	uint8_t checksum = data[0] + data[1] + data[2] + data[3];
+	if (checksum != data[4])
+	return -1;
+
+	// Extract temperature and humidity
+	*humidity = ((data[0] << 8) | data[1]);
+	*temperature = ((data[2] << 8) | data[3]);
+
+	return 0;
+}
+

DHT22.h

@@ -0,0 +1,7 @@
+#ifndef DHT22_H
+#define DHT22_H
+
+int DHT22_Read(int *temperature, int *humidity);
+void DHT22_Init();
+
+#endif /* DHT22_H */

GDM1602K.c

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+#include "config.h"
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <stdbool.h>
+
+#define LCD_DATA_PORT   PORTB
+#define LCD_DATA_DDR    DDRB
+#define LCD_RS_PIN      PB1
+#define LCD_EN_PIN      PB2
+#define LCD_DB4			PB3
+#define LCD_DB5			PB4
+#define LCD_DB6			PB5
+#define LCD_DB7			PB6
+
+// Delay constants from the datasheet. These are mostly in nanoseconds
+#define LAG 10
+#define TW 300
+#define TSU1 100
+
+void lcd_4bit_init() {
+	LCD_DATA_DDR = 0xFF;
+	LCD_DATA_PORT = (1 << LCD_DB5);
+	LCD_DATA_PORT &= ~(1 << LCD_RS_PIN);
+	_delay_us(1);
+	LCD_DATA_PORT |= (1 << LCD_EN_PIN);
+	_delay_us(1);
+	LCD_DATA_PORT &= ~(1 << LCD_EN_PIN);
+	_delay_us(1);
+	LCD_DATA_PORT &= ~(1 << LCD_DB5);
+	_delay_us(1);
+}
+
+void lcd_send(bool rs, uint8_t data) {
+	LCD_DATA_DDR = 0xFF;
+	LCD_DATA_PORT = 0x00;
+
+	LCD_DATA_PORT |= (data >> 4) << 3;
+	_delay_us(1);
+	
+	// If rs (actual text data), set RS pin high
+	if(rs == true) LCD_DATA_PORT |= (1 << LCD_RS_PIN);
+
+	// Pulse enable
+	_delay_ms(2);
+	LCD_DATA_PORT |= (1 << LCD_EN_PIN);
+
+	_delay_us(1);
+	LCD_DATA_PORT &= ~(1 << LCD_EN_PIN);
+
+	//_delay_us(1);
+	
+	// Clear data pins
+	LCD_DATA_PORT &= ~(0x0F << 3);
+	
+	// Mask the lower bits and shift accordingly
+	LCD_DATA_PORT |= (data & 0x0F) << 3;
+	_delay_us(1);
+	
+	// Pulse enable
+	LCD_DATA_PORT |= (1 << LCD_EN_PIN);
+	_delay_us(1);
+	LCD_DATA_PORT &= ~(1 << LCD_EN_PIN);
+	_delay_us(1);
+	LCD_DATA_PORT &= ~(0x0F << 3);
+	
+	LCD_DATA_PORT &= ~(1 << LCD_RS_PIN); // RS Low
+}
+
+void lcd_init() {
+	_delay_ms(100);
+	lcd_4bit_init();
+
+	//lcd_send(1, 0b01111000);
+	lcd_send(0, 0x01); // Clear screen
+	lcd_send(0, 0x02); // Return home
+	lcd_send(0, 0b00001100); // Display on, no cursor
+	lcd_send(0, 0b00101000);
+}
+
+void lcd_clear() {
+	lcd_send(0, 0x01);
+}
+
+void test_leds() {
+		DDRB |= 0xFF;
+		PORTB = (1 << LCD_DB4);
+		_delay_us(1);
+		PORTB = (1 << LCD_DB5);
+		_delay_us(1);
+		PORTB = (1 << LCD_DB6);
+		_delay_us(1);
+		PORTB = (1 << LCD_DB7);
+		_delay_us(1);
+		
+		PORTB = (1 << LCD_EN_PIN);
+		_delay_us(1);
+		PORTB = (1 << LCD_RS_PIN);
+		_delay_us(1);
+		PORTB = 0x00;
+}
+
+void lcd_set_cursor(uint8_t row, uint8_t col) {
+	uint8_t position = 0x80;
+	
+	if (row == 1) position += 0x40;
+	
+	position += col;
+	lcd_send(0, position);
+}
+
+// Takes a string and splits it over two lines if needed. Max length is 32 characters.
+void lcd_write_string(const char* string) {
+	uint8_t i = 0;
+	while(string[i]) {
+		if(i == 16) {
+			lcd_set_cursor(1, 0);
+			while(string[i] == ' ') i++; // Skip leading spaces on the new line
+		}
+		lcd_send(1, string[i]);
+		i++;
+	}
+}
+
+// Takes two separate strings and prints them on their corresponding row
+void lcd_write_strings(const char* top, const char* bottom) {
+	uint8_t i = 0;
+	
+	while (top[i]) {
+		lcd_send(1, top[i]);
+		i++;
+	}
+	
+	i = 0;
+	lcd_set_cursor(1, 0);
+	while(bottom[i]) {
+		lcd_send(1, bottom[i]);
+		i++;
+	}
+	
+}

GDM1602K.h

@@ -0,0 +1,9 @@
+#ifndef GDM1602K_H_
+#define GDM1602K_H_
+
+void lcd_write_strings(const char* top, const char* bottom);
+void lcd_write_string(const char* string);
+void lcd_init();
+void lcd_clear();
+
+#endif /* GDM1602K_H_ */

LM335.c

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+#include "config.h"
+#include <avr/io.h>
+#include <util/delay.h>
+#include "LM335.h"
+
+void ADC_Init()
+{
+    // Set AVCC as the voltage reference with external capacitor at AREF pin
+    ADMUX = (1 << REFS0);
+
+    // Set ADC clock prescaler to 64 (125kHz ADC clock)
+    ADCSRA = (1 << ADPS2) | (1 << ADPS1);
+
+    // Enable ADC, enable interrupts
+    ADCSRA |= (1 << ADEN); // | (1 << ADIE);
+}
+
+uint16_t ADC_Read(uint8_t channel)
+{
+    // Select ADC channel
+    ADMUX = (ADMUX & 0xF8) | (channel & 0x07);
+
+    // Start ADC conversion
+    ADCSRA |= (1 << ADSC);
+
+    // Wait for ADC conversion to complete
+    while (ADCSRA & (1 << ADSC))
+        ;
+
+    // Read ADC result
+    return ADC;
+}
+
+float LM335_ReadTemperature()
+{
+    // Read ADC value from LM335 pin (PA0)
+    uint16_t adcValue = ADC_Read(0x00);
+
+	float vref = 4.64;
+	int vfactor = 100;
+	float voltage = (adcValue * vref) / 1024;
+
+    // Calculate temperature in Celsius using LM335 formula
+    float temperature = (voltage - 2.92) * vfactor;
+
+    return temperature;
+}

LM335.h

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+#include <avr/io.h>
+#include <util/delay.h>
+
+#ifndef LM335_H_
+#define LM335_H_
+
+#define LM335_PIN PA0
+
+void ADC_Init();
+uint16_t ADC_Read(uint8_t channel);
+float LM335_ReadTemperature();
+
+#endif

config.h

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+#ifndef CONFIG_H
+#define CONFIG_H
+
+#define F_CPU 1600000UL
+
+#endif // CONFIG_H

main.c

@@ -0,0 +1,94 @@
+#include "config.h"
+
+#include <avr/io.h>
+#include <stdbool.h>
+#include <util/delay.h>
+#include <stdio.h>
+
+#include "74C922.h"
+#include "DHT22.h"
+#include "GDM1602K.h"
+#include "LM335.h"
+
+enum DisplayMode {TEMP, AVG};
+
+bool b = false;
+
+int main() {
+	_delay_ms(1000); // Boot up time, let components catch up
+	lcd_init();
+	encoder_init();
+
+	lcd_clear();
+	lcd_write_string("Hello, world!");
+
+	int temp, hum;
+	char celc_str[30];
+	char temp_with_unit[20] = "";
+	char hum_str[30];
+	float celcius = 0.0;
+	float humidity = 0.0;
+	char temp_unit = 'C';
+
+	uint8_t button_data;
+	char btn_string[30];
+	bool btn_just_pressed = false;
+
+	long loops = 0;
+
+	while(1) {
+		// If encoder has data available
+		if(encoder_available() == true) {
+			loops = 0xFFFF;
+			if(!btn_just_pressed) {
+				btn_just_pressed = true;
+				button_data = encoder_read();
+				sprintf(btn_string, "Knapp %d", button_data);
+				lcd_clear();
+				if(button_data == 11) {
+					if(temp_unit == 'C') temp_unit = 'F';
+					else if(temp_unit == 'F') temp_unit = 'K';
+					else if(temp_unit == 'K') temp_unit = 'C';
+					loops = 0;
+				} 
+				if(button_data == 3) {
+					sprintf(celc_str, "10h Tmp: %s", temp_with_unit);
+					sprintf(hum_str, "10h Hum: %.1f%%", humidity-1);	
+					lcd_write_strings(celc_str, hum_str);
+				}
+			}
+		} else {
+			btn_just_pressed = false;
+		}
+		
+		if(loops == 0) {
+			loops = 0x2FFFF;
+
+			int result = DHT22_Read(&temp, &hum);
+
+			lcd_clear();
+
+			if(result == 0) {
+				celcius = ((float)temp)/10.0;
+				humidity = ((float) hum)/10.0;
+				switch(temp_unit) {
+					case 'C':
+						sprintf(temp_with_unit, "%.1f %c", celcius, temp_unit);
+						break;
+					case 'F':
+						sprintf(temp_with_unit, "%.1f %c", celcius*9/5+32, temp_unit);
+						break;
+					case 'K':
+						sprintf(temp_with_unit, "%.1f %c", celcius + 273.15, temp_unit);
+						break;
+				}
+				sprintf(celc_str, "Temp: %s", temp_with_unit);
+				sprintf(hum_str, "Humidity: %.1f%%", humidity);
+				
+				lcd_write_strings(celc_str, hum_str);
+			}
+		}
+		loops--;
+	}
+	lcd_write_string("Exited...");
+}