1 /* Library made by: g4lvanix
2 * Github repository: https://github.com/g4lvanix/I2C-master-lib
8 #include "i2c_master.h"
11 #define F_SCL 400000UL // SCL frequency
13 #define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16 ) / 2)
17 TWSR = 0; /* no prescaler */
18 TWBR = (uint8_t)TWBR_val;
21 i2c_status_t i2c_start(uint8_t address, uint16_t timeout)
23 // reset TWI control register
25 // transmit START condition
26 TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
28 uint16_t timeout_timer = timer_read();
29 while( !(TWCR & (1<<TWINT)) ) {
30 if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
31 return I2C_STATUS_TIMEOUT;
35 // check if the start condition was successfully transmitted
36 if(((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)){ return I2C_STATUS_ERROR; }
38 // load slave address into data register
40 // start transmission of address
41 TWCR = (1<<TWINT) | (1<<TWEN);
43 timeout_timer = timer_read();
44 while( !(TWCR & (1<<TWINT)) ) {
45 if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
46 return I2C_STATUS_TIMEOUT;
50 // check if the device has acknowledged the READ / WRITE mode
51 uint8_t twst = TW_STATUS & 0xF8;
52 if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return I2C_STATUS_ERROR;
54 return I2C_STATUS_SUCCESS;
57 i2c_status_t i2c_write(uint8_t data, uint16_t timeout)
59 // load data into data register
61 // start transmission of data
62 TWCR = (1<<TWINT) | (1<<TWEN);
64 uint16_t timeout_timer = timer_read();
65 while( !(TWCR & (1<<TWINT)) ) {
66 if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
67 return I2C_STATUS_TIMEOUT;
71 if( (TW_STATUS & 0xF8) != TW_MT_DATA_ACK ){ return I2C_STATUS_ERROR; }
73 return I2C_STATUS_SUCCESS;
76 int16_t i2c_read_ack(uint16_t timeout)
79 // start TWI module and acknowledge data after reception
80 TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
82 uint16_t timeout_timer = timer_read();
83 while( !(TWCR & (1<<TWINT)) ) {
84 if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
85 return I2C_STATUS_TIMEOUT;
89 // return received data from TWDR
93 int16_t i2c_read_nack(uint16_t timeout)
96 // start receiving without acknowledging reception
97 TWCR = (1<<TWINT) | (1<<TWEN);
99 uint16_t timeout_timer = timer_read();
100 while( !(TWCR & (1<<TWINT)) ) {
101 if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
102 return I2C_STATUS_TIMEOUT;
106 // return received data from TWDR
110 i2c_status_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)
112 i2c_status_t status = i2c_start(address | I2C_WRITE, timeout);
113 if (status) return status;
115 for (uint16_t i = 0; i < length; i++) {
116 status = i2c_write(data[i], timeout);
117 if (status) return status;
120 status = i2c_stop(timeout);
121 if (status) return status;
123 return I2C_STATUS_SUCCESS;
126 i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)
128 i2c_status_t status = i2c_start(address | I2C_READ, timeout);
129 if (status) return status;
131 for (uint16_t i = 0; i < (length-1); i++) {
132 status = i2c_read_ack(timeout);
140 status = i2c_read_nack(timeout);
142 data[(length-1)] = status;
147 status = i2c_stop(timeout);
148 if (status) return status;
150 return I2C_STATUS_SUCCESS;
153 i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)
155 i2c_status_t status = i2c_start(devaddr | 0x00, timeout);
156 if (status) return status;
158 status = i2c_write(regaddr, timeout);
159 if (status) return status;
161 for (uint16_t i = 0; i < length; i++) {
162 status = i2c_write(data[i], timeout);
163 if (status) return status;
166 status = i2c_stop(timeout);
167 if (status) return status;
169 return I2C_STATUS_SUCCESS;
172 i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)
174 i2c_status_t status = i2c_start(devaddr, timeout);
175 if (status) return status;
177 status = i2c_write(regaddr, timeout);
178 if (status) return status;
180 status = i2c_start(devaddr | 0x01, timeout);
181 if (status) return status;
183 for (uint16_t i = 0; i < (length-1); i++) {
184 status = i2c_read_ack(timeout);
192 status = i2c_read_nack(timeout);
194 data[(length-1)] = status;
199 status = i2c_stop(timeout);
200 if (status) return status;
202 return I2C_STATUS_SUCCESS;
205 i2c_status_t i2c_stop(uint16_t timeout)
207 // transmit STOP condition
208 TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
210 uint16_t timeout_timer = timer_read();
211 while(TWCR & (1<<TWSTO)) {
212 if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
213 return I2C_STATUS_TIMEOUT;
217 return I2C_STATUS_SUCCESS;