blob: a417098fecc7e5ca5eba298ee8956c560970b235 (
plain)
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
|
/*
pollserial.cpp Heavily modified version of:
HardwareSerial.cpp - Hardware serial library for Wiring
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Modified 23 November 2006 by David A. Mellis
Modified July 2010 by Myles D. Metzler
*/
#include <avr/io.h>
#include <stdlib.h>
#include "pollserial.h"
#define BUFFER_SIZE 64
rbuffer rxbuffer = {0,0,0};
void USART_recieve() {
#if defined ( UDR0 )
if( UCSR0A & _BV(RXC0)) {
uint8_t i = (rxbuffer.head + 1) & (BUFFER_SIZE - 1);
if ( i != rxbuffer.tail) {
rxbuffer.buffer[rxbuffer.head] = UDR0;
rxbuffer.head = i;
}
}
#else
if( UCSRA & _BV(RXC)) {
uint8_t i = (rxbuffer.head + 1) & (BUFFER_SIZE - 1);
if ( i != rxbuffer.tail) {
rxbuffer.buffer[rxbuffer.head] = UDR;
rxbuffer.head = i;
}
}
#endif
}
pt2Funct pollserial::begin(long baud) {
uint16_t baud_setting;
bool use_u2x;
rxbuffer.buffer = (unsigned char*)malloc(BUFFER_SIZE*sizeof(unsigned char));
// U2X mode is needed for baud rates higher than (CPU Hz / 16)
if (baud > F_CPU / 16) {
use_u2x = true;
}
else {
// figure out if U2X mode would allow for a better connection
// calculate the percent difference between the baud-rate specified and
// the real baud rate for both U2X and non-U2X mode (0-255 error percent)
uint8_t nonu2x_baud_error = abs((int)(255-((F_CPU/(16*(((F_CPU/8/baud-1)/2)+1))*255)/baud)));
uint8_t u2x_baud_error = abs((int)(255-((F_CPU/(8*(((F_CPU/4/baud-1)/2)+1))*255)/baud)));
// prefer non-U2X mode because it handles clock skew better
use_u2x = (nonu2x_baud_error > u2x_baud_error);
}
if (use_u2x) {
#if defined ( UDR0 )
UCSR0A = _BV(U2X0);
#else
UCSRA = _BV(U2X);
#endif
baud_setting = (F_CPU / 4 / baud - 1) / 2;
}
else {
#if defined ( UDR0 )
UCSR0A = 0;
#else
UCSRA = 0;
#endif
baud_setting = (F_CPU / 8 / baud - 1) / 2;
}
// assign the baud_setting, a.k.a. (USART Baud Rate Register)
#if defined ( UDR0 )
UBRR0 = baud_setting;
UCSR0B = _BV(RXEN0) | _BV(TXEN0);
#else
UBRR = baud_setting;
UCSRB = _BV(RXEN) | _BV(TXEN);
#endif
return &USART_recieve;
}
void pollserial::end() {
UCSR0B &= ~(_BV(RXEN0) | _BV(TXEN0));
free(rxbuffer.buffer);
}
uint8_t pollserial::available() {
return (BUFFER_SIZE + rxbuffer.head - rxbuffer.tail) & (BUFFER_SIZE-1);
}
int pollserial::read() {
if (rxbuffer.head == rxbuffer.tail)
return -1;
else {
uint8_t c = rxbuffer.buffer[rxbuffer.tail];
//tail = (tail + 1) & 63;
if (rxbuffer.tail == BUFFER_SIZE)
rxbuffer.tail = 0;
else
rxbuffer.tail++;
return c;
}
}
void pollserial::flush() {
rxbuffer.head = rxbuffer.tail;
}
size_t pollserial::write(uint8_t c) {
#if defined ( UDR0 )
while (!((UCSR0A) & _BV(UDRE0)));
UDR0 = c;
#else
while (!((UCSRA) & _BV(UDRE)));
UDR = c;
#endif
}
|
