70 lines
No EOL
1.7 KiB
C
70 lines
No EOL
1.7 KiB
C
#include "i2c.h"
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#include <avr/io.h>
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#include <util/delay.h>
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#include <util/twi.h>
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#include <stdint.h>
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void I2C_init() {
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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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uint8_t I2C_start(uint8_t addr) {
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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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// Load the address of the slave device
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TWDR = addr;
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// Clear the TWINT bit to start the transmission
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TWCR = (1 << TWINT) | (1 << TWEN);
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// Wait for the address to be sent
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while (!(TWCR & (1 << TWINT)))
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;
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// Get the status of the transmission
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uint8_t status = TWSR & 0xF8;
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// Return true if the slave acknowledged the address
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return (status == TW_MT_SLA_ACK || status == TW_MR_SLA_ACK);
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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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}
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uint8_t 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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// Return true if the data was sent
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return (TWSR & 0xF8) == TW_MT_DATA_ACK;
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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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;
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// Return received data
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return TWDR;
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} |