-
-
Notifications
You must be signed in to change notification settings - Fork 107
/
I2CManager_Mega4809.h
159 lines (140 loc) · 5.4 KB
/
I2CManager_Mega4809.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
/*
* © 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_MEGA4809_H
#define I2CMANAGER_MEGA4809_H
#include <Arduino.h>
#include "I2CManager.h"
/***************************************************************************
* Set I2C clock speed register.
***************************************************************************/
void I2CManagerClass::I2C_setClock(unsigned long i2cClockSpeed) {
uint16_t t_rise;
if (i2cClockSpeed < 200000)
t_rise = 1000;
else if (i2cClockSpeed < 800000)
t_rise = 300;
else
t_rise = 120;
if (t_rise == 120)
TWI0.CTRLA |= TWI_FMPEN_bm;
else
TWI0.CTRLA &= ~TWI_FMPEN_bm;
uint32_t baud = (F_CPU_CORRECTED / i2cClockSpeed - F_CPU_CORRECTED / 1000 / 1000
* t_rise / 1000 - 10) / 2;
if (baud > 255) baud = 255; // ~30kHz
TWI0.MBAUD = (uint8_t)baud;
}
/***************************************************************************
* Initialise I2C registers.
***************************************************************************/
void I2CManagerClass::I2C_init()
{
pinMode(PIN_WIRE_SDA, INPUT_PULLUP);
pinMode(PIN_WIRE_SCL, INPUT_PULLUP);
PORTMUX.TWISPIROUTEA |= TWI_MUX;
I2C_setClock(I2C_FREQ);
#if defined(I2C_USE_INTERRUPTS)
TWI0.MCTRLA = TWI_RIEN_bm | TWI_WIEN_bm | TWI_ENABLE_bm;
#else
TWI0.MCTRLA = TWI_ENABLE_bm;
#endif
TWI0.MSTATUS = TWI_BUSSTATE_IDLE_gc;
}
/***************************************************************************
* Initiate a start bit for transmission, followed by address and R/W
***************************************************************************/
void I2CManagerClass::I2C_sendStart() {
txCount = 0;
rxCount = 0;
// If anything to send, initiate write. Otherwise initiate read.
if (operation == OPERATION_READ || ((operation == OPERATION_REQUEST) && !bytesToSend))
TWI0.MADDR = (currentRequest->i2cAddress << 1) | 1;
else
TWI0.MADDR = (currentRequest->i2cAddress << 1) | 0;
}
/***************************************************************************
* Initiate a stop bit for transmission.
***************************************************************************/
void I2CManagerClass::I2C_sendStop() {
TWI0.MCTRLB = TWI_MCMD_STOP_gc;
}
/***************************************************************************
* Close I2C down
***************************************************************************/
void I2CManagerClass::I2C_close() {
TWI0.MCTRLA &= ~(TWI_RIEN_bm | TWI_WIEN_bm | TWI_ENABLE_bm); // Switch off I2C
TWI0.MSTATUS = TWI_BUSSTATE_UNKNOWN_gc;
delayMicroseconds(10); // Wait for things to stabilise (hopefully)
}
/***************************************************************************
* Main state machine for I2C, called from interrupt handler.
***************************************************************************/
void I2CManagerClass::I2C_handleInterrupt() {
uint8_t currentStatus = TWI0.MSTATUS;
if (currentStatus & TWI_ARBLOST_bm) {
// Arbitration lost, restart
TWI0.MSTATUS = currentStatus; // clear all flags
I2C_sendStart(); // Reinitiate request
} else if (currentStatus & TWI_BUSERR_bm) {
// Bus error
completionStatus = I2C_STATUS_BUS_ERROR;
state = I2C_STATE_COMPLETED;
TWI0.MSTATUS = currentStatus; // clear all flags
} else if (currentStatus & TWI_WIF_bm) {
// Master write completed
if (currentStatus & TWI_RXACK_bm) {
// Nacked, send stop.
TWI0.MCTRLB = TWI_MCMD_STOP_gc;
completionStatus = I2C_STATUS_NEGATIVE_ACKNOWLEDGE;
state = I2C_STATE_COMPLETED;
} else if (bytesToSend) {
// Acked, so send next byte (don't need to use GETFLASH)
TWI0.MDATA = sendBuffer[txCount++];
bytesToSend--;
} else if (bytesToReceive) {
// Last sent byte acked and no more to send. Send repeated start, address and read bit.
TWI0.MADDR = (deviceAddress << 1) | 1;
} else {
// No more data to send/receive. Initiate a STOP condition.
TWI0.MCTRLB = TWI_MCMD_STOP_gc;
state = I2C_STATE_COMPLETED;
}
} else if (currentStatus & TWI_RIF_bm) {
// Master read completed without errors
if (bytesToReceive) {
receiveBuffer[rxCount++] = TWI0.MDATA; // Store received byte
bytesToReceive--;
}
if (bytesToReceive) {
// More bytes to receive, issue ack and start another read
TWI0.MCTRLB = TWI_MCMD_RECVTRANS_gc;
} else {
// Transaction finished, issue NACK and STOP.
TWI0.MCTRLB = TWI_ACKACT_bm | TWI_MCMD_STOP_gc;
state = I2C_STATE_COMPLETED;
}
}
}
/***************************************************************************
* Interrupt handler.
***************************************************************************/
ISR(TWI0_TWIM_vect) {
I2CManager.handleInterrupt();
}
#endif