141 lines
3.7 KiB
C
141 lines
3.7 KiB
C
/*
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* This code utilizes the AVR libraries for I2C and UART communication.
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* Make sure to connect the SDA and SCL pins of the ATmega328P to the
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* corresponding pins of your I2C temperature sensor. Additionally, you might
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* need pull-up resistors for the I2C lines.
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*/
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#include <avr/io.h>
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#include <util/delay.h>
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#include <math.h>
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#define LED_PIN PB5 // Define the pin connected to the LED
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#define TEMP_SENSOR_ADDR 0x48
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#define TEMP_REG_ADDR 0x00
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#define BAUD 9600
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void initI2C() {
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// Set the prescaler to 1
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TWSR &= ~(1 << TWPS0);
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TWSR &= ~(1 << TWPS1);
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// Set the bit rate to 100kHz
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TWBR = ((F_CPU / 100000) - 16) / 2;
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}
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void I2C_start() {
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// Send the start condition
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TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
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// Wait for the start condition to be sent
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while (!(TWCR & (1 << TWINT)))
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;
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}
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void I2C_stop() {
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// Send the stop condition
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TWCR = (1 << TWINT) | (1 << TWSTO) | (1 << TWEN);
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// Wait for the stop condition to be sent
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while (TWCR & (1 << TWSTO));
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}
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void I2C_write(uint8_t data) {
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// Load the data into the data register
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TWDR = data;
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// Start transmission of data
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TWCR = (1 << TWINT) | (1 << TWEN);
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// Wait for the data to be sent
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while (!(TWCR & (1 << TWINT)));
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}
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uint8_t I2C_read(uint8_t ack) {
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// Enable TWI, generate ACK (if ack = 1) and clear TWI interrupt flag
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TWCR = (1 << TWINT) | (1 << TWEN) | (ack << TWEA);
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// Wait until TWI finish its current job (read operation)
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while (!(TWCR & (1 << TWINT)));
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// Return received data
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return TWDR;
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}
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void initUART() {
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// Set baud rate
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UBRR0H = (uint8_t)(F_CPU / (BAUD * 16UL) - 1) >> 8;
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UBRR0L = (uint8_t)(F_CPU / (BAUD * 16UL) - 1);
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// Enable receiver and transmitter
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UCSR0B |= (1 << RXEN0) | (1 << TXEN0);
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// Set frame format: 8 data, 1 stop bit
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UCSR0C |= (1 << UCSZ01) | (1 << UCSZ00);
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}
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void UART_transmit(uint8_t data) {
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// Wait for empty transmit buffer
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while (!(UCSR0A & (1 << UDRE0)));
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// Put data into buffer, sends the data
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UDR0 = data;
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}
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void UART_println(const char *str) {
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// Transmit each character until NULL character is encountered
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while (*str) UART_transmit(*str++);
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// Transmit carriage return and line feed characters
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UART_transmit('\r');
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UART_transmit('\n');
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}
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float readTemperature() {
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uint16_t temperature;
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// Send start condition
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I2C_start();
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// Send device address with write operation
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I2C_write((TEMP_SENSOR_ADDR << 1) | 0);
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// Send temperature register address
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I2C_write(0x00);
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// Repeat start
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I2C_start();
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// Send device address with read operation
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I2C_write((TEMP_SENSOR_ADDR << 1) | 1);
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// Read temperature data MSB
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temperature = (uint16_t)(I2C_read(1)) << 8;
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// Read temperature data LSB
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temperature |= I2C_read(0);
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// Send stop condition
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I2C_stop();
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// Convert raw data to temperature in Celsius
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return (float)temperature * 0.0625;
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}
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int main(void) {
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initI2C();
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initUART();
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float temperature;
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while (1) {
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temperature = readTemperature();
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// Print temperature over UART
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UART_println("Temperature: ");
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UART_transmit((uint8_t)(temperature / 10.0) + '0');
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UART_transmit((uint8_t)fmod(temperature, 10.0) + '0');
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UART_println(" °C");
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_delay_ms(1000); // Delay for 1 second
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}
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return 0;
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}
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void blink() {
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// Set the LED pin as output
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DDRB |= (1 << LED_PIN);
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while (1) {
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// Turn on the LED by setting the pin high
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PORTB |= (1 << LED_PIN);
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// Delay for 500 milliseconds
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_delay_ms(500);
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// Turn off the LED by setting the pin low
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PORTB &= ~(1 << LED_PIN);
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// Delay for 500 milliseconds
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_delay_ms(500);
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}
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}
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