root / scout_avr / bom / bom.c @ 5f7a1707
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1 | f572eaeb | Tom Mullins | #include <stdint.h> |
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2 | #include <avr/io.h> |
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3 | #include <avr/interrupt.h> |
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4 | 5f7a1707 | Tom Mullins | #include <util/delay.h> |
5 | cbe25c0a | tmullins | #include "tiny-twi.h" |
6 | f572eaeb | Tom Mullins | #include "bomi2c.h" |
7 | |||
8 | char last_bit;
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9 | char count;
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10 | uint16_t data; |
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11 | f8c1522b | Aaron Perley | volatile char currently_sending; |
12 | char sending_counter;
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13 | uint16_t sending_data; |
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14 | f572eaeb | Tom Mullins | |
15 | #define READ_BIT(pin, bit) (((pin) >> bit) & 1) |
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16 | #define SET_BIT(pin, bit) ((pin) |= (1 << (bit))) |
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17 | c7445989 | Tom Mullins | #define CLEAR_BIT(pin, bit) ((pin) &= ~(1 << (bit))) |
18 | f8c1522b | Aaron Perley | #define PRESCALAR 8 |
19 | #define TIME_US(us) (F_CPU * (us) / 1000000 / PRESCALAR) |
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20 | f572eaeb | Tom Mullins | |
21 | cbe25c0a | tmullins | #define ADDRESS 0x3 |
22 | 1b05b4cc | Aaron Perley | #define DETECT PB3
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23 | b2554c5c | Aaron Perley | #define EMIT PB4
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24 | f572eaeb | Tom Mullins | |
25 | 1b05b4cc | Aaron Perley | #if DETECT == PB3
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26 | #define PCINT_DETECT PCINT3
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27 | #endif
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28 | #if DETECT == PB4
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29 | #define PCINT_DETECT PCINT4
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30 | #endif
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31 | f572eaeb | Tom Mullins | |
32 | 1b05b4cc | Aaron Perley | static void bom_init(void) { |
33 | 5f7a1707 | Tom Mullins | |
34 | SET_BIT(DDRB, EMIT); |
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35 | |||
36 | 1b05b4cc | Aaron Perley | init_detect(); |
37 | f8c1522b | Aaron Perley | |
38 | b2554c5c | Aaron Perley | init_timer1(); |
39 | f572eaeb | Tom Mullins | |
40 | c7445989 | Tom Mullins | sei(); |
41 | f572eaeb | Tom Mullins | } |
42 | |||
43 | b2554c5c | Aaron Perley | ////////////////////////////////// Receiving ///////////////////////////////////
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44 | |||
45 | 1b05b4cc | Aaron Perley | static void init_detect(void) { |
46 | e4d78d85 | Julian Binder | TCCR0A |= _BV(WGM01); // enable reset on compare A
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47 | b2554c5c | Aaron Perley | TIMSK |= _BV(OCIE0A); // enable timer0 compare match A
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48 | 5f7a1707 | Tom Mullins | OCR0A = TIME_US(1000); // trigger every 1ms |
49 | 1b05b4cc | Aaron Perley | |
50 | 5f7a1707 | Tom Mullins | GIFR |= _BV(PCIF); // Clear any previous detections
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51 | 1b05b4cc | Aaron Perley | GIMSK |= _BV(PCIE); // Enable pin change interrupt for detection
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52 | PCMSK |= _BV(PCINT_DETECT); // Enable interrupt on detect pin
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53 | } |
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54 | |||
55 | // Disables the interrupt that begins the detect process while it is running
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56 | static void disable_detect_interrupt(void) { |
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57 | PCMSK &= ~_BV(PCINT_DETECT); |
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58 | b2554c5c | Aaron Perley | } |
59 | |||
60 | static void start_timer0(void) { |
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61 | TCNT0 = 0; // Reset timer 0 count to 0 |
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62 | TCCR0B |= _BV(CS01); // setup clkio and start the timer
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63 | } |
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64 | |||
65 | static void start_detect(void) { |
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66 | 1b05b4cc | Aaron Perley | disable_detect_interrupt(); |
67 | b2554c5c | Aaron Perley | data = 0;
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68 | count = 0;
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69 | last_bit = 1;
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70 | 5f7a1707 | Tom Mullins | _delay_us(160);
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71 | b2554c5c | Aaron Perley | start_timer0(); |
72 | } |
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73 | |||
74 | 1b05b4cc | Aaron Perley | static void restart_detect(void) { |
75 | b2554c5c | Aaron Perley | TCCR0B &= ~0x07; // Stop timer0 |
76 | 1b05b4cc | Aaron Perley | PCMSK |= _BV(PCINT_DETECT); // Enable interrupt on detect pin
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77 | } |
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78 | |||
79 | ISR(PCINT0_vect) { |
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80 | start_detect(); |
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81 | b2554c5c | Aaron Perley | } |
82 | |||
83 | f572eaeb | Tom Mullins | ISR(TIMER0_COMPA_vect) { |
84 | |||
85 | b2554c5c | Aaron Perley | char this_bit = READ_BIT(PINB, DETECT);
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86 | 5f7a1707 | Tom Mullins | smb_send_data((uint8_t*)&this_bit, 1);
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87 | f572eaeb | Tom Mullins | |
88 | 5f7a1707 | Tom Mullins | if (this_bit == 1) { |
89 | if (last_bit == 1) { |
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90 | 1b05b4cc | Aaron Perley | restart_detect(); |
91 | f572eaeb | Tom Mullins | } |
92 | } else {
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93 | 5f7a1707 | Tom Mullins | data = data << 1 | (last_bit & 1); |
94 | f572eaeb | Tom Mullins | count++; |
95 | } |
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96 | |||
97 | last_bit = this_bit; |
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98 | |||
99 | if (count == 15) { |
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100 | 1b05b4cc | Aaron Perley | restart_detect(); |
101 | e4d78d85 | Julian Binder | smb_send_data((uint8_t*) &data, sizeof(data));
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102 | f572eaeb | Tom Mullins | } |
103 | } |
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104 | |||
105 | b2554c5c | Aaron Perley | ////////////////////////////////////////////////////////////////////////////////
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106 | |||
107 | //////////////////////////////////// Sending ///////////////////////////////////
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108 | |||
109 | static void start_timer1() { |
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110 | TCNT1 = 0; // Reset timer 1 count to 0 |
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111 | e4d78d85 | Julian Binder | TCCR1 |= _BV(CS12); // Set prescalar to 8 and start timer1
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112 | b2554c5c | Aaron Perley | } |
113 | |||
114 | static void stop_timer1() { |
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115 | TCCR1 &= ~0x0F; // Stop the timer without clearing CTC1 |
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116 | } |
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117 | |||
118 | static void init_timer1() { |
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119 | OCR1B = TIME_US(320); // Set match b to fire every 320 us |
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120 | TIMSK |= _BV(OCIE1A) | _BV(OCIE1B); // Enable interrupt for match a and b
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121 | TCCR1 |= _BV(CTC1); // Enables resetting timer1 after matches match c
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122 | } |
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123 | |||
124 | static void send_data(uint16_t data) { |
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125 | sending_data = data; |
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126 | sending_counter = 0;
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127 | currently_sending = 1;
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128 | SET_BIT(PORTB, EMIT); |
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129 | |||
130 | start_timer1(); |
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131 | send_next_bit(); |
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132 | } |
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133 | |||
134 | f8c1522b | Aaron Perley | static void send_next_bit() { |
135 | c7445989 | Tom Mullins | char next_bit = sending_data >> (14 - sending_counter) & 1; |
136 | char ocr_temp = next_bit ? TIME_US(2000-40) : TIME_US(1000-20); |
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137 | b2554c5c | Aaron Perley | OCR1A = ocr_temp; // Compare A - Turns on transmitter
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138 | OCR1C = ocr_temp; // Reset the timer when match a fires
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139 | f572eaeb | Tom Mullins | } |
140 | |||
141 | b2554c5c | Aaron Perley | // Compare A - Turns on transmitter
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142 | f8c1522b | Aaron Perley | ISR(TIMER1_COMPA_vect) { |
143 | b2554c5c | Aaron Perley | SET_BIT(PORTB, EMIT); |
144 | c7445989 | Tom Mullins | sending_counter++; |
145 | send_next_bit(); |
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146 | } |
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147 | |||
148 | b2554c5c | Aaron Perley | // Compare B - Turns off transmitter after 320us
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149 | c7445989 | Tom Mullins | ISR(TIMER1_COMPB_vect) { |
150 | b2554c5c | Aaron Perley | CLEAR_BIT(PORTB, EMIT); |
151 | c7445989 | Tom Mullins | if (sending_counter >= 15) { |
152 | f8c1522b | Aaron Perley | currently_sending = 0;
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153 | b2554c5c | Aaron Perley | stop_timer1(); |
154 | f572eaeb | Tom Mullins | } |
155 | } |
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156 | |||
157 | b2554c5c | Aaron Perley | ////////////////////////////////////////////////////////////////////////////////
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158 | |||
159 | c7445989 | Tom Mullins | |
160 | cbe25c0a | tmullins | static void slave_rx(uint8_t *buf, int len) { |
161 | if (len >= 3) { |
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162 | switch (buf[0]) { |
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163 | case BOM_I2C_SEND:
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164 | if (!currently_sending) send_data((uint16_t) buf[1] << 8 | buf[2]); |
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165 | break;
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166 | } |
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167 | } |
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168 | } |
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169 | |||
170 | |||
171 | c7445989 | Tom Mullins | |
172 | f572eaeb | Tom Mullins | int main() {
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173 | bom_init(); |
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174 | cbe25c0a | tmullins | smb_init(slave_rx); |
175 | smb_set_address(ADDRESS); |
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176 | for (;;);;;;;;;;;;;;;;;;;
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177 | f572eaeb | Tom Mullins | } |