forked from DCC-EX/CommandStation-EX
-
Notifications
You must be signed in to change notification settings - Fork 0
/
I2CManager_AVR.h
230 lines (200 loc) · 9.05 KB
/
I2CManager_AVR.h
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
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
/*
* © 2023, Neil McKechnie. All rights reserved.
*
* This file is part of CommandStation-EX
*
* This 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.
*
* It 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 CommandStation. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef I2CMANAGER_AVR_H
#define I2CMANAGER_AVR_H
#include <Arduino.h>
#include "I2CManager.h"
#include "I2CManager_NonBlocking.h" // to satisfy intellisense
#include <avr/io.h>
#include <avr/interrupt.h>
/****************************************************************************
TWI State codes
****************************************************************************/
// General TWI Master staus codes
#define TWI_START 0x08 // START has been transmitted
#define TWI_REP_START 0x10 // Repeated START has been transmitted
#define TWI_ARB_LOST 0x38 // Arbitration lost
// TWI Master Transmitter staus codes
#define TWI_MTX_ADR_ACK 0x18 // SLA+W has been tramsmitted and ACK received
#define TWI_MTX_ADR_NACK 0x20 // SLA+W has been tramsmitted and NACK received
#define TWI_MTX_DATA_ACK 0x28 // Data byte has been tramsmitted and ACK received
#define TWI_MTX_DATA_NACK 0x30 // Data byte has been tramsmitted and NACK received
// TWI Master Receiver staus codes
#define TWI_MRX_ADR_ACK 0x40 // SLA+R has been tramsmitted and ACK received
#define TWI_MRX_ADR_NACK 0x48 // SLA+R has been tramsmitted and NACK received
#define TWI_MRX_DATA_ACK 0x50 // Data byte has been received and ACK tramsmitted
#define TWI_MRX_DATA_NACK 0x58 // Data byte has been received and NACK tramsmitted
// TWI Miscellaneous status codes
#define TWI_NO_STATE 0xF8 // No relevant state information available
#define TWI_BUS_ERROR 0x00 // Bus error due to an illegal START or STOP condition
#define TWI_TWBR ((F_CPU / I2C_FREQ) - 16) / 2 // TWI Bit rate Register setting.
#if defined(I2C_USE_INTERRUPTS)
#define ENABLE_TWI_INTERRUPT (1<<TWIE)
#else
#define ENABLE_TWI_INTERRUPT 0
#endif
/***************************************************************************
* Set I2C clock speed register.
***************************************************************************/
void I2CManagerClass::I2C_setClock(unsigned long i2cClockSpeed) {
unsigned long temp = ((F_CPU / i2cClockSpeed) - 16) / 2;
for (uint8_t preScaler = 0; preScaler<=3; preScaler++) {
if (temp <= 255) {
TWBR = temp;
TWSR = (TWSR & 0xfc) | preScaler;
return;
} else
temp /= 4;
}
// Set slowest speed ~= 500 bits/sec
TWBR = 255;
TWSR |= 0x03;
}
/***************************************************************************
* Initialise I2C registers.
***************************************************************************/
void I2CManagerClass::I2C_init()
{
TWSR = 0;
TWBR = TWI_TWBR; // Set bit rate register (Baudrate). Defined in header file.
TWDR = 0xFF; // Default content = SDA released.
TWCR = (1<<TWINT); // Clear interrupt flag
pinMode(SDA, INPUT_PULLUP);
pinMode(SCL, INPUT_PULLUP);
}
/***************************************************************************
* Initiate a start bit for transmission.
***************************************************************************/
void I2CManagerClass::I2C_sendStart() {
rxCount = 0;
txCount = 0;
// We may have already triggered a stop bit in the same run as this. To avoid
// clearing that bit before the stop bit has been sent, we can either wait for
// it to complete or we can OR the bit onto the existing bits.
TWCR |= (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA)|(1<<TWSTA); // Send Start
}
/***************************************************************************
* Initiate a stop bit for transmission (does not interrupt)
***************************************************************************/
void I2CManagerClass::I2C_sendStop() {
TWDR = 0xff; // Default condition = SDA released
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWSTO); // Send Stop
}
/***************************************************************************
* Close I2C down
***************************************************************************/
void I2CManagerClass::I2C_close() {
// disable TWI
TWCR = (1<<TWINT); // clear any interrupt and stop twi.
delayMicroseconds(10); // Wait for things to stabilise (hopefully)
}
/***************************************************************************
* Main state machine for I2C, called from interrupt handler or,
* if I2C_USE_INTERRUPTS isn't defined, from the I2CManagerClass::loop() function
* (and therefore, indirectly, from I2CRB::wait() and I2CRB::isBusy()).
***************************************************************************/
void I2CManagerClass::I2C_handleInterrupt() {
if (!(TWCR & (1<<TWINT))) return; // Nothing to do.
uint8_t twsr = TWSR & 0xF8;
// Main I2C interrupt handler, used for the device communications.
// The following variables are used:
// bytesToSend, bytesToReceive (R/W)
// txCount, rxCount (W)
// deviceAddress (R)
// sendBuffer, receiveBuffer (R)
// operation (R)
// state, completionStatus (W)
//
// Cases are ordered so that the most frequently used ones are tested first.
switch (twsr) {
case TWI_MTX_DATA_ACK: // Data byte has been transmitted and ACK received
case TWI_MTX_ADR_ACK: // SLA+W has been transmitted and ACK received
if (bytesToSend) { // Send first.
if (operation == OPERATION_SEND_P)
TWDR = GETFLASH(sendBuffer + (txCount++));
else
TWDR = sendBuffer[txCount++];
bytesToSend--;
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT);
} else if (bytesToReceive) { // All sent, anything to receive?
// Don't need to wait for stop, as the interface won't send the start until
// any in-progress stop condition from previous interrupts has been sent.
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWSTA); // Send Start
} else {
// Nothing left to send or receive
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
state = I2C_STATE_COMPLETED;
}
break;
case TWI_MRX_DATA_ACK: // Data byte has been received and ACK transmitted
if (bytesToReceive > 0) {
receiveBuffer[rxCount++] = TWDR;
bytesToReceive--;
}
/* fallthrough */
case TWI_MRX_ADR_ACK: // SLA+R has been sent and ACK received
if (bytesToReceive <= 1) {
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT); // Send NACK after next reception
} else {
// send ack
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA);
}
break;
case TWI_MRX_DATA_NACK: // Data byte has been received and NACK transmitted
if (bytesToReceive > 0) {
receiveBuffer[rxCount++] = TWDR;
bytesToReceive--;
}
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
state = I2C_STATE_COMPLETED;
break;
case TWI_START: // START has been transmitted
case TWI_REP_START: // Repeated START has been transmitted
// Set up address and R/W
if (operation == OPERATION_READ || (operation==OPERATION_REQUEST && !bytesToSend))
TWDR = (deviceAddress << 1) | 1; // SLA+R
else
TWDR = (deviceAddress << 1) | 0; // SLA+W
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA);
break;
case TWI_MTX_ADR_NACK: // SLA+W has been transmitted and NACK received
case TWI_MRX_ADR_NACK: // SLA+R has been transmitted and NACK received
case TWI_MTX_DATA_NACK: // Data byte has been transmitted and NACK received
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
completionStatus = I2C_STATUS_NEGATIVE_ACKNOWLEDGE;
state = I2C_STATE_COMPLETED;
break;
case TWI_ARB_LOST: // Arbitration lost
// Restart transaction from start.
I2C_sendStart();
break;
case TWI_BUS_ERROR: // Bus error due to an illegal START or STOP condition
default:
TWDR = 0xff; // Default condition = SDA released
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
completionStatus = I2C_STATUS_TRANSMIT_ERROR;
state = I2C_STATE_COMPLETED;
}
}
#if defined(I2C_USE_INTERRUPTS)
ISR(TWI_vect) {
I2CManager.handleInterrupt();
}
#endif
#endif /* I2CMANAGER_AVR_H */