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
|
/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 LeafLabs LLC.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*****************************************************************************/
/**
* @file Wire.cpp
* @author Trystan Jones <crenn6977@gmail.com>
* @brief Wire library, uses the WireBase to create the primary interface
* while keeping low level interactions invisible to the user.
*/
/*
* Library updated by crenn to follow new Wire system.
* Code was derived from the original Wire for maple code by leaflabs and the
* modifications by gke and ala42.
*/
#include "Wire.h"
#define I2C_WRITE 0
#define I2C_READ 1
/* low level conventions:
* - SDA/SCL idle high (expected high)
* - always start with i2c_delay rather than end
*/
void TwoWire::set_scl(bool state) {
I2C_DELAY(this->i2c_delay);
digitalWrite(this->scl_pin,state);
//Allow for clock stretching - dangerous currently
if (state == HIGH) {
while(digitalRead(this->scl_pin) == 0);
}
}
void TwoWire::set_sda(bool state) {
I2C_DELAY(this->i2c_delay);
digitalWrite(this->sda_pin, state);
}
void TwoWire::i2c_start() {
set_sda(LOW);
set_scl(LOW);
}
void TwoWire::i2c_stop() {
set_sda(LOW);
set_scl(HIGH);
set_sda(HIGH);
}
bool TwoWire::i2c_get_ack() {
set_scl(LOW);
set_sda(HIGH);
set_scl(HIGH);
bool ret = !digitalRead(this->sda_pin);
set_scl(LOW);
return ret;
}
void TwoWire::i2c_send_ack() {
set_sda(LOW);
set_scl(HIGH);
set_scl(LOW);
}
void TwoWire::i2c_send_nack() {
set_sda(HIGH);
set_scl(HIGH);
set_scl(LOW);
}
uint8 TwoWire::i2c_shift_in() {
uint8 data = 0;
set_sda(HIGH);
int i;
for (i = 0; i < 8; i++) {
set_scl(HIGH);
data |= digitalRead(this->sda_pin) << (7-i);
set_scl(LOW);
}
return data;
}
void TwoWire::i2c_shift_out(uint8 val) {
int i;
for (i = 0; i < 8; i++) {
set_sda(!!(val & (1 << (7 - i)) ) );
set_scl(HIGH);
set_scl(LOW);
}
}
uint8 TwoWire::process() {
itc_msg.xferred = 0;
uint8 sla_addr = (itc_msg.addr << 1);
if (itc_msg.flags == I2C_MSG_READ) {
sla_addr |= I2C_READ;
}
i2c_start();
// shift out the address we're transmitting to
i2c_shift_out(sla_addr);
if (!i2c_get_ack()) {
return ENACKADDR;
}
// Recieving
if (itc_msg.flags == I2C_MSG_READ) {
while (itc_msg.xferred < itc_msg.length) {
itc_msg.data[itc_msg.xferred++] = i2c_shift_in();
if (itc_msg.xferred < itc_msg.length) {
i2c_send_ack();
} else {
i2c_send_nack();
}
}
}
// Sending
else {
for (uint8 i = 0; i < itc_msg.length; i++) {
i2c_shift_out(itc_msg.data[i]);
if (!i2c_get_ack()) {
return ENACKTRNS;
}
itc_msg.xferred++;
}
}
i2c_stop();
return SUCCESS;
}
// TODO: Add in Error Handling if pins is out of range for other Maples
// TODO: Make delays more capable
TwoWire::TwoWire(uint8 scl, uint8 sda, uint8 delay) : i2c_delay(delay) {
this->scl_pin=scl;
this->sda_pin=sda;
}
void TwoWire::begin(uint8 self_addr) {
tx_buf_idx = 0;
tx_buf_overflow = false;
rx_buf_idx = 0;
rx_buf_len = 0;
pinMode(this->scl_pin, OUTPUT_OPEN_DRAIN);
pinMode(this->sda_pin, OUTPUT_OPEN_DRAIN);
set_scl(HIGH);
set_sda(HIGH);
}
TwoWire::~TwoWire() {
this->scl_pin=0;
this->sda_pin=0;
}
// Declare the instance that the users of the library can use
TwoWire Wire();
|
