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