]> git.gir.st - tmk_keyboard.git/blob - protocol/serial_soft.c
Merge branch 'sun'
[tmk_keyboard.git] / protocol / serial_soft.c
1 /*
2 Copyright 2012 Jun WAKO <wakojun@gmail.com>
3
4 This software is licensed with a Modified BSD License.
5 All of this is supposed to be Free Software, Open Source, DFSG-free,
6 GPL-compatible, and OK to use in both free and proprietary applications.
7 Additions and corrections to this file are welcome.
8
9
10 Redistribution and use in source and binary forms, with or without
11 modification, are permitted provided that the following conditions are met:
12
13 * Redistributions of source code must retain the above copyright
14 notice, this list of conditions and the following disclaimer.
15
16 * Redistributions in binary form must reproduce the above copyright
17 notice, this list of conditions and the following disclaimer in
18 the documentation and/or other materials provided with the
19 distribution.
20
21 * Neither the name of the copyright holders nor the names of
22 contributors may be used to endorse or promote products derived
23 from this software without specific prior written permission.
24
25 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
26 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
29 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 POSSIBILITY OF SUCH DAMAGE.
36 */
37
38 #include <stdbool.h>
39 #include <avr/io.h>
40 #include <avr/interrupt.h>
41 #include <util/delay.h>
42 #include "serial.h"
43
44 /*
45 * Stupid Inefficient Busy-wait Software Serial
46 * is still useful for negative logic signal like Sun protocol not supported by hardware USART.
47 */
48
49 #define WAIT_US (1000000/SERIAL_BAUD)
50
51 void serial_init(void)
52 {
53 SERIAL_RXD_INIT();
54 }
55
56 // RX ring buffer
57 #define RBUF_SIZE 8
58 static uint8_t rbuf[RBUF_SIZE];
59 static uint8_t rbuf_head = 0;
60 static uint8_t rbuf_tail = 0;
61
62 uint8_t serial_recv(void)
63 {
64 uint8_t data = 0;
65 if (rbuf_head == rbuf_tail) {
66 return 0;
67 }
68
69 data = rbuf[rbuf_tail];
70 rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
71 return data;
72 }
73
74 //ISR(INT2_vect)
75 ISR(SERIAL_RXD_VECT)
76 {
77 SERIAL_RXD_INT_ENTER()
78
79 uint8_t data = 0;
80 #ifdef SERIAL_BIT_ORDER_MSB
81 uint8_t pos = 0x80;
82 #else
83 uint8_t pos = 0x01;
84 #endif
85 // to center of start bit
86 _delay_us(WAIT_US/2);
87 do {
88 // to center of next bit
89 _delay_us(WAIT_US);
90
91 if (SERIAL_RXD_PIN&(1<<SERIAL_RXD_BIT)) {
92 data |= pos;
93 }
94 #ifdef SERIAL_BIT_ORDER_MSB
95 pos >>= 1;
96 #else
97 pos <<= 1;
98 #endif
99 } while (pos);
100 // to center of stop bit
101 _delay_us(WAIT_US);
102
103 #ifdef SERIAL_NEGATIVE_LOGIC
104 data = ~data;
105 #endif
106
107 uint8_t next = (rbuf_head + 1) % RBUF_SIZE;
108 if (next != rbuf_tail) {
109 rbuf[rbuf_head] = data;
110 rbuf_head = next;
111 }
112
113 SERIAL_RXD_INT_EXIT();
114 }
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