root / scout_avr / bom / bom.c @ b2554c5c
History | View | Annotate | Download (3.37 KB)
1 | f572eaeb | Tom Mullins | #include <stdint.h> |
---|---|---|---|
2 | #include <avr/io.h> |
||
3 | #include <avr/interrupt.h> |
||
4 | cbe25c0a | tmullins | #include "tiny-twi.h" |
5 | f572eaeb | Tom Mullins | #include "bomi2c.h" |
6 | |||
7 | char last_bit;
|
||
8 | char count;
|
||
9 | uint16_t data; |
||
10 | f8c1522b | Aaron Perley | volatile char currently_sending; |
11 | char sending_counter;
|
||
12 | uint16_t sending_data; |
||
13 | f572eaeb | Tom Mullins | |
14 | #define READ_BIT(pin, bit) (((pin) >> bit) & 1) |
||
15 | #define SET_BIT(pin, bit) ((pin) |= (1 << (bit))) |
||
16 | c7445989 | Tom Mullins | #define CLEAR_BIT(pin, bit) ((pin) &= ~(1 << (bit))) |
17 | f8c1522b | Aaron Perley | #define PRESCALAR 8 |
18 | #define TIME_US(us) (F_CPU * (us) / 1000000 / PRESCALAR) |
||
19 | f572eaeb | Tom Mullins | |
20 | cbe25c0a | tmullins | #define ADDRESS 0x3 |
21 | b2554c5c | Aaron Perley | #define DETECT PB2
|
22 | #define EMIT PB4
|
||
23 | f572eaeb | Tom Mullins | |
24 | static void bom_init(void) { |
||
25 | |||
26 | // setup INT0
|
||
27 | //EICRA |= _BV(ISC01) | _BV(ISC00);
|
||
28 | //EIMSK |= _BV(INT0);
|
||
29 | |||
30 | b2554c5c | Aaron Perley | init_timer0(); |
31 | start_timer0(); |
||
32 | f8c1522b | Aaron Perley | |
33 | b2554c5c | Aaron Perley | init_timer1(); |
34 | f572eaeb | Tom Mullins | |
35 | // setup output pin
|
||
36 | c7445989 | Tom Mullins | SET_BIT(DDRB, 4);
|
37 | f572eaeb | Tom Mullins | |
38 | c7445989 | Tom Mullins | sei(); |
39 | f572eaeb | Tom Mullins | bom_start(); |
40 | } |
||
41 | |||
42 | b2554c5c | Aaron Perley | ////////////////////////////////// Receiving ///////////////////////////////////
|
43 | |||
44 | static void init_timer0(void) { |
||
45 | TCCROA |= _BV(WGM01); // enable reset on compare A
|
||
46 | TIMSK |= _BV(OCIE0A); // enable timer0 compare match A
|
||
47 | } |
||
48 | |||
49 | static void start_timer0(void) { |
||
50 | TCNT0 = 0; // Reset timer 0 count to 0 |
||
51 | TCCR0B |= _BV(CS01); // setup clkio and start the timer
|
||
52 | } |
||
53 | |||
54 | static void start_detect(void) { |
||
55 | data = 0;
|
||
56 | count = 0;
|
||
57 | last_bit = 1;
|
||
58 | start_timer0(); |
||
59 | } |
||
60 | |||
61 | static void stop_detect(void) { |
||
62 | TCCR0B &= ~0x07; // Stop timer0 |
||
63 | } |
||
64 | |||
65 | f572eaeb | Tom Mullins | ISR(TIMER0_COMPA_vect) { |
66 | |||
67 | b2554c5c | Aaron Perley | char this_bit = READ_BIT(PINB, DETECT);
|
68 | f572eaeb | Tom Mullins | |
69 | if (this_bit == 0) { |
||
70 | if (last_bit == 0) { |
||
71 | b2554c5c | Aaron Perley | stop_detect(); |
72 | f572eaeb | Tom Mullins | } |
73 | } else {
|
||
74 | data = data << 1 | (~last_bit & 1); |
||
75 | count++; |
||
76 | } |
||
77 | |||
78 | last_bit = this_bit; |
||
79 | |||
80 | if (count == 15) { |
||
81 | b2554c5c | Aaron Perley | stop_detect(); |
82 | cbe25c0a | tmullins | smb_send_data(&data, sizeof(data));
|
83 | f572eaeb | Tom Mullins | } |
84 | } |
||
85 | |||
86 | b2554c5c | Aaron Perley | ////////////////////////////////////////////////////////////////////////////////
|
87 | |||
88 | //////////////////////////////////// Sending ///////////////////////////////////
|
||
89 | |||
90 | static void start_timer1() { |
||
91 | TCNT1 = 0; // Reset timer 1 count to 0 |
||
92 | TCCR1 |= _BV(CS12) // Set prescalar to 8 and start timer1
|
||
93 | } |
||
94 | |||
95 | static void stop_timer1() { |
||
96 | TCCR1 &= ~0x0F; // Stop the timer without clearing CTC1 |
||
97 | } |
||
98 | |||
99 | static void init_timer1() { |
||
100 | OCR1B = TIME_US(320); // Set match b to fire every 320 us |
||
101 | TIMSK |= _BV(OCIE1A) | _BV(OCIE1B); // Enable interrupt for match a and b
|
||
102 | TCCR1 |= _BV(CTC1); // Enables resetting timer1 after matches match c
|
||
103 | } |
||
104 | |||
105 | static void send_data(uint16_t data) { |
||
106 | sending_data = data; |
||
107 | sending_counter = 0;
|
||
108 | currently_sending = 1;
|
||
109 | SET_BIT(PORTB, EMIT); |
||
110 | |||
111 | start_timer1(); |
||
112 | send_next_bit(); |
||
113 | } |
||
114 | |||
115 | f8c1522b | Aaron Perley | static void send_next_bit() { |
116 | c7445989 | Tom Mullins | char next_bit = sending_data >> (14 - sending_counter) & 1; |
117 | char ocr_temp = next_bit ? TIME_US(2000-40) : TIME_US(1000-20); |
||
118 | b2554c5c | Aaron Perley | OCR1A = ocr_temp; // Compare A - Turns on transmitter
|
119 | OCR1C = ocr_temp; // Reset the timer when match a fires
|
||
120 | f572eaeb | Tom Mullins | } |
121 | |||
122 | b2554c5c | Aaron Perley | // Compare A - Turns on transmitter
|
123 | f8c1522b | Aaron Perley | ISR(TIMER1_COMPA_vect) { |
124 | b2554c5c | Aaron Perley | SET_BIT(PORTB, EMIT); |
125 | c7445989 | Tom Mullins | sending_counter++; |
126 | send_next_bit(); |
||
127 | } |
||
128 | |||
129 | b2554c5c | Aaron Perley | // Compare B - Turns off transmitter after 320us
|
130 | c7445989 | Tom Mullins | ISR(TIMER1_COMPB_vect) { |
131 | b2554c5c | Aaron Perley | CLEAR_BIT(PORTB, EMIT); |
132 | c7445989 | Tom Mullins | if (sending_counter >= 15) { |
133 | f8c1522b | Aaron Perley | currently_sending = 0;
|
134 | b2554c5c | Aaron Perley | stop_timer1(); |
135 | f572eaeb | Tom Mullins | } |
136 | } |
||
137 | |||
138 | b2554c5c | Aaron Perley | ////////////////////////////////////////////////////////////////////////////////
|
139 | |||
140 | c7445989 | Tom Mullins | |
141 | ISR(INT0_vect) { |
||
142 | bom_start(); |
||
143 | } |
||
144 | |||
145 | |||
146 | cbe25c0a | tmullins | |
147 | static void slave_rx(uint8_t *buf, int len) { |
||
148 | if (len >= 3) { |
||
149 | switch (buf[0]) { |
||
150 | case BOM_I2C_SEND:
|
||
151 | if (!currently_sending) send_data((uint16_t) buf[1] << 8 | buf[2]); |
||
152 | break;
|
||
153 | } |
||
154 | } |
||
155 | } |
||
156 | |||
157 | |||
158 | c7445989 | Tom Mullins | |
159 | f572eaeb | Tom Mullins | int main() {
|
160 | bom_init(); |
||
161 | cbe25c0a | tmullins | smb_init(slave_rx); |
162 | smb_set_address(ADDRESS); |
||
163 | for (;;);;;;;;;;;;;;;;;;;
|
||
164 | f572eaeb | Tom Mullins | } |