1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
/* Library made by: g4lvanix
* Github repository: https://github.com/g4lvanix/I2C-master-lib
*/
#include <avr/io.h>
#include <util/twi.h>
#include "i2c_master.h"
#include "timer.h"
#include "wait.h"
#ifndef F_SCL
# define F_SCL 400000UL // SCL frequency
#endif
#define Prescaler 1
#define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16) / 2)
void i2c_init(void) {
TWSR = 0; /* no prescaler */
TWBR = (uint8_t)TWBR_val;
}
i2c_status_t i2c_start(uint8_t address, uint16_t timeout) {
// reset TWI control register
TWCR = 0;
// transmit START condition
TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
uint16_t timeout_timer = timer_read();
while (!(TWCR & (1 << TWINT))) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// check if the start condition was successfully transmitted
if (((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)) {
return I2C_STATUS_ERROR;
}
// load slave address into data register
TWDR = address;
// start transmission of address
TWCR = (1 << TWINT) | (1 << TWEN);
timeout_timer = timer_read();
while (!(TWCR & (1 << TWINT))) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// check if the device has acknowledged the READ / WRITE mode
uint8_t twst = TW_STATUS & 0xF8;
if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) {
return I2C_STATUS_ERROR;
}
return I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_write(uint8_t data, uint16_t timeout) {
// load data into data register
TWDR = data;
// start transmission of data
TWCR = (1 << TWINT) | (1 << TWEN);
uint16_t timeout_timer = timer_read();
while (!(TWCR & (1 << TWINT))) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
if ((TW_STATUS & 0xF8) != TW_MT_DATA_ACK) {
return I2C_STATUS_ERROR;
}
return I2C_STATUS_SUCCESS;
}
int16_t i2c_read_ack(uint16_t timeout) {
// start TWI module and acknowledge data after reception
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA);
uint16_t timeout_timer = timer_read();
while (!(TWCR & (1 << TWINT))) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// return received data from TWDR
return TWDR;
}
int16_t i2c_read_nack(uint16_t timeout) {
// start receiving without acknowledging reception
TWCR = (1 << TWINT) | (1 << TWEN);
uint16_t timeout_timer = timer_read();
while (!(TWCR & (1 << TWINT))) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// return received data from TWDR
return TWDR;
}
i2c_status_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout) {
i2c_status_t status = i2c_start(address | I2C_WRITE, timeout);
for (uint16_t i = 0; i < length && status >= 0; i++) {
status = i2c_write(data[i], timeout);
}
i2c_stop();
return status;
}
i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout) {
i2c_status_t status = i2c_start(address | I2C_READ, timeout);
for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) {
status = i2c_read_ack(timeout);
if (status >= 0) {
data[i] = status;
}
}
if (status >= 0) {
status = i2c_read_nack(timeout);
if (status >= 0) {
data[(length - 1)] = status;
}
}
i2c_stop();
return status;
}
i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout) {
i2c_status_t status = i2c_start(devaddr | 0x00, timeout);
if (status >= 0) {
status = i2c_write(regaddr, timeout);
for (uint16_t i = 0; i < length && status >= 0; i++) {
status = i2c_write(data[i], timeout);
}
}
i2c_stop();
return status;
}
i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout) {
i2c_status_t status = i2c_start(devaddr, timeout);
if (status < 0) {
goto error;
}
status = i2c_write(regaddr, timeout);
if (status < 0) {
goto error;
}
status = i2c_start(devaddr | 0x01, timeout);
for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) {
status = i2c_read_ack(timeout);
if (status >= 0) {
data[i] = status;
}
}
if (status >= 0) {
status = i2c_read_nack(timeout);
if (status >= 0) {
data[(length - 1)] = status;
}
}
error:
i2c_stop();
return status;
}
void i2c_stop(void) {
// transmit STOP condition
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
}
|
