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
|
/* Copyright (C) 2019 Elia Ritterbusch
+
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/* Library made by: g4lvanix
* GitHub repository: https://github.com/g4lvanix/I2C-slave-lib
*/
#include <stddef.h>
#include <avr/io.h>
#include <util/twi.h>
#include <avr/interrupt.h>
#include <stdbool.h>
#include "i2c_slave.h"
#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
# include "transactions.h"
static volatile bool is_callback_executor = false;
#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
volatile uint8_t i2c_slave_reg[I2C_SLAVE_REG_COUNT];
static volatile uint8_t buffer_address;
static volatile bool slave_has_register_set = false;
void i2c_slave_init(uint8_t address) {
// load address into TWI address register
TWAR = address;
// set the TWCR to enable address matching and enable TWI, clear TWINT, enable TWI interrupt
TWCR = (1 << TWIE) | (1 << TWEA) | (1 << TWINT) | (1 << TWEN);
}
void i2c_slave_stop(void) {
// clear acknowledge and enable bits
TWCR &= ~((1 << TWEA) | (1 << TWEN));
}
ISR(TWI_vect) {
uint8_t ack = 1;
switch (TW_STATUS) {
case TW_SR_SLA_ACK:
// The device is now a slave receiver
slave_has_register_set = false;
#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
is_callback_executor = false;
#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
break;
case TW_SR_DATA_ACK:
// This device is a slave receiver and has received data
// First byte is the location then the bytes will be writen in buffer with auto-increment
if (!slave_has_register_set) {
buffer_address = TWDR;
if (buffer_address >= I2C_SLAVE_REG_COUNT) { // address out of bounds dont ack
ack = 0;
buffer_address = 0;
}
slave_has_register_set = true; // address has been received now fill in buffer
#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
// Work out if we're attempting to execute a callback
is_callback_executor = buffer_address == split_transaction_table[I2C_EXECUTE_CALLBACK].initiator2target_offset;
#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
} else {
i2c_slave_reg[buffer_address] = TWDR;
buffer_address++;
#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
// If we're intending to execute a transaction callback, do so, as we've just received the transaction ID
if (is_callback_executor) {
split_transaction_desc_t *trans = &split_transaction_table[split_shmem->transaction_id];
if (trans->slave_callback) {
trans->slave_callback(trans->initiator2target_buffer_size, split_trans_initiator2target_buffer(trans), trans->target2initiator_buffer_size, split_trans_target2initiator_buffer(trans));
}
}
#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
}
break;
case TW_ST_SLA_ACK:
case TW_ST_DATA_ACK:
// This device is a slave transmitter and master has requested data
TWDR = i2c_slave_reg[buffer_address];
buffer_address++;
break;
case TW_BUS_ERROR:
// We got an error, reset i2c
TWCR = 0;
default:
break;
}
// Reset i2c state machine to be ready for next interrupt
TWCR |= (1 << TWIE) | (1 << TWINT) | (ack << TWEA) | (1 << TWEN);
}
|
