/scout_avr/bom/bom.c - Annotate - Colony Scout OS - Robotics Club

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	}

Project

General

Profile

Colony » Colony Scout » Colony Scout OS

root / scout_avr / bom / bom.c @ b2554c5c