root / scout_avr / src / bom.cpp @ c06735bb
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| 1 | f115416e | Tom Mullins | extern "C" { |
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| 2 | #include <avr/io.h> |
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| 3 | #include <avr/interrupt.h> |
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| 4 | #include <util/delay.h> |
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| 5 | } |
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| 6 | #include "bom.h" |
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| 7 | |||
| 8 | /*
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| 9 | * Sharp protocol:
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| 10 | * Period modulation
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| 11 | * 1: 2ms period
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| 12 | * 0: 1ms period
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| 13 | * Signal:
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| 14 | * 38kHz pulse for 320us, then off for rest of time (680us or 1680us)
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| 15 | 812788aa | Tom Mullins | * BOM uses timer 4 for period timing, and timer 0 for 38kHz signal
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| 16 | f115416e | Tom Mullins | */
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| 17 | |||
| 18 | 63e19141 | Tom Mullins | /*
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| 19 | * Recently modified so that when BOM is sending, it stops listening. When
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| 20 | * not sending, it keeps listening.
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| 21 | */
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| 22 | |||
| 23 | f115416e | Tom Mullins | #define TIME_MICROS(us, prescale) (F_CPU / 1000000 * (us) / (prescale)) |
| 24 | |||
| 25 | typedef uint16_t sharp_msg_t;
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| 26 | |||
| 27 | static sharp_msg_t sharp_msg_make(char address, bom_msg_t bom_msg) { |
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| 28 | return (((uint16_t)address & 0x3F) << 10) | ((uint16_t)bom_msg << 2) | 2; |
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| 29 | } |
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| 30 | |||
| 31 | static char robot_id; |
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| 32 | |||
| 33 | // tx global vars
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| 34 | static sharp_msg_t out_msg;
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| 35 | static uint8_t out_pin_mask;
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| 36 | static char out_high, out_counter; |
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| 37 | static volatile char out_done; |
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| 38 | |||
| 39 | // rx global vars
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| 40 | static uint8_t prev_bom_sig;
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| 41 | static struct bom_rx_t { |
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| 42 | 31f4a032 | Tom Mullins | uint8_t count; |
| 43 | f115416e | Tom Mullins | uint16_t bits; |
| 44 | 31f4a032 | Tom Mullins | int last_time;
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| 45 | f115416e | Tom Mullins | |
| 46 | uint8_t new_data; |
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| 47 | uint8_t address; |
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| 48 | uint8_t data; |
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| 49 | } bom_rx[4];
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| 50 | |||
| 51 | void set_robot_id(char id) { |
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| 52 | robot_id = id; |
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| 53 | } |
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| 54 | |||
| 55 | char get_robot_id(void) { |
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| 56 | return robot_id;
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| 57 | } |
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| 58 | |||
| 59 | 812788aa | Tom Mullins | void bom_isr() {
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| 60 | f115416e | Tom Mullins | if (out_high) {
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| 61 | cc9ca04e | Tom Mullins | PORT_BOM_EMIT ^= out_pin_mask; |
| 62 | f115416e | Tom Mullins | } |
| 63 | } |
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| 64 | |||
| 65 | static void init_38kHz_signal() { |
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| 66 | out_high = 0;
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| 67 | out_pin_mask = 0;
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| 68 | 63e19141 | Tom Mullins | |
| 69 | 812788aa | Tom Mullins | // timer configuration now done in Atmega128rfa1.cpp
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| 70 | f115416e | Tom Mullins | } |
| 71 | |||
| 72 | static void start_38kHz_signal() { |
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| 73 | TCNT3 = 0;
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| 74 | cc9ca04e | Tom Mullins | PORT_BOM_EMIT |= out_pin_mask; |
| 75 | f115416e | Tom Mullins | out_high = 1;
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| 76 | } |
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| 77 | |||
| 78 | static void stop_38kHz_signal() { |
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| 79 | 63e19141 | Tom Mullins | PORT_BOM_EMIT &= ~ out_pin_mask; // why not just do PORT_BOM_EMIT &= 0; ?
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| 80 | f115416e | Tom Mullins | out_high = 0;
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| 81 | } |
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| 82 | |||
| 83 | static void init_data_signal() { |
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| 84 | // timer 4 mode CTC (clear timer on compare), TOP = OCRA
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| 85 | TCCR4A = 0;
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| 86 | TCCR4B = _BV(WGM42); |
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| 87 | 63e19141 | Tom Mullins | |
| 88 | f115416e | Tom Mullins | // run interrupt immediately when timer started
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| 89 | OCR4A = 0;
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| 90 | 63e19141 | Tom Mullins | |
| 91 | f115416e | Tom Mullins | // enable interrupt
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| 92 | TIMSK4 = _BV(OCIE4A); |
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| 93 | } |
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| 94 | |||
| 95 | static void start_data_signal() { |
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| 96 | TCNT4 = 0;
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| 97 | 63e19141 | Tom Mullins | |
| 98 | f115416e | Tom Mullins | // start timer 4 at F_CPU/64 prescaling
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| 99 | TCCR4B |= _BV(CS41) | _BV(CS40); |
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| 100 | } |
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| 101 | |||
| 102 | static void stop_data_signal() { |
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| 103 | // stop timer 4
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| 104 | TCCR4B &= ~ (_BV(CS42) | _BV(CS41) | _BV(CS40)); |
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| 105 | } |
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| 106 | |||
| 107 | ISR(TIMER4_COMPA_vect) {
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| 108 | 31f4a032 | Tom Mullins | if (out_high) {
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| 109 | stop_38kHz_signal(); |
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| 110 | if (out_counter) {
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| 111 | out_counter--; |
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| 112 | if ((out_msg >> out_counter) & 1) { |
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| 113 | f115416e | Tom Mullins | OCR4A = TIME_MICROS(1680, 64); |
| 114 | } else {
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| 115 | OCR4A = TIME_MICROS(680, 64); |
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| 116 | } |
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| 117 | } else {
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| 118 | 31f4a032 | Tom Mullins | stop_data_signal(); |
| 119 | out_done = 1;
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| 120 | f115416e | Tom Mullins | } |
| 121 | } else {
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| 122 | 31f4a032 | Tom Mullins | start_38kHz_signal(); |
| 123 | OCR4A = TIME_MICROS(320, 64); |
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| 124 | f115416e | Tom Mullins | } |
| 125 | } |
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| 126 | |||
| 127 | void bom_init(void) { |
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| 128 | // BOM_SIG as input, interrupts enabled
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| 129 | DDRB &= ~ (_BV(DDB0) | _BV(DDB1) | _BV(DDB2) | _BV(DDB3)); |
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| 130 | PCMSK0 |= _BV(PCINT0) | _BV(PCINT1) | _BV(PCINT2) | _BV(PCINT3); |
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| 131 | PCICR |= _BV(PCIE0); |
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| 132 | 63e19141 | Tom Mullins | |
| 133 | f115416e | Tom Mullins | // BOM_EMIT as output
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| 134 | cc9ca04e | Tom Mullins | DDRF |= _BV(DDF4) | _BV(DDF5) | _BV(DDF6) | _BV(DDF7); |
| 135 | f115416e | Tom Mullins | |
| 136 | init_38kHz_signal(); |
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| 137 | init_data_signal(); |
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| 138 | } |
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| 139 | |||
| 140 | 63e19141 | Tom Mullins | static void stop_receiving(char dir) { |
| 141 | switch (dir) {
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| 142 | case BOM_FRONT: PCMSK0 &= ~_BV(PCINT0); break; |
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| 143 | case BOM_LEFT : PCMSK0 &= ~_BV(PCINT1); break; |
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| 144 | case BOM_RIGHT: PCMSK0 &= ~_BV(PCINT2); break; |
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| 145 | case BOM_BACK : PCMSK0 &= ~_BV(PCINT3); break; |
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| 146 | } |
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| 147 | } |
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| 148 | |||
| 149 | static void start_receiving(char dir) { |
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| 150 | // flush rx buffer before turning on the receiver
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| 151 | bom_rx[(int)dir].bits = 0; |
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| 152 | bom_rx[(int)dir].count = 0; |
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| 153 | |||
| 154 | switch (dir) {
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| 155 | case BOM_FRONT: PCMSK0 |= _BV(PCINT0); break; |
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| 156 | case BOM_LEFT : PCMSK0 |= _BV(PCINT1); break; |
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| 157 | case BOM_RIGHT: PCMSK0 |= _BV(PCINT2); break; |
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| 158 | case BOM_BACK : PCMSK0 |= _BV(PCINT3); break; |
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| 159 | } |
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| 160 | } |
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| 161 | |||
| 162 | f115416e | Tom Mullins | void bom_send(char dir) { |
| 163 | switch (dir) {
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| 164 | cc9ca04e | Tom Mullins | case BOM_FRONT: out_pin_mask = _BV(P_BOM_EMIT0); break; |
| 165 | case BOM_LEFT: out_pin_mask = _BV(P_BOM_EMIT1); break; |
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| 166 | case BOM_RIGHT: out_pin_mask = _BV(P_BOM_EMIT2); break; |
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| 167 | case BOM_BACK: out_pin_mask = _BV(P_BOM_EMIT3); break; |
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| 168 | f115416e | Tom Mullins | } |
| 169 | 31f4a032 | Tom Mullins | out_counter = 16;
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| 170 | f115416e | Tom Mullins | out_msg = sharp_msg_make(0x2A, bom_msg_make(robot_id, dir));
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| 171 | out_done = 0;
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| 172 | 63e19141 | Tom Mullins | |
| 173 | stop_receiving(dir); // disable receiver
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| 174 | start_38kHz_signal(); // enable the transmitter
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| 175 | f115416e | Tom Mullins | start_data_signal(); |
| 176 | while (!out_done) {
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| 177 | _delay_ms(0.1); |
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| 178 | } |
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| 179 | 63e19141 | Tom Mullins | stop_data_signal(); // disable the transmitter
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| 180 | stop_38kHz_signal(); |
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| 181 | start_receiving(dir); // enable the receiver
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| 182 | f115416e | Tom Mullins | } |
| 183 | |||
| 184 | static void recv_edge(char is_rising, struct bom_rx_t *rx) { |
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| 185 | if (is_rising) {
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| 186 | 31f4a032 | Tom Mullins | // TODO check 320us? or have 320us timeout on rising edge?
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| 187 | } else {
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| 188 | 399f7d1b | Tom Mullins | // uses timer 5, assuming prescale 1/64
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| 189 | 812788aa | Tom Mullins | // timer 5 is set up by range_init()
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| 190 | 399f7d1b | Tom Mullins | int now = TCNT5;
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| 191 | int min_low = TIME_MICROS(MIN_LOW_PW, 64); |
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| 192 | int max_low = TIME_MICROS(MAX_LOW_PW, 64); |
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| 193 | int min_high = TIME_MICROS(MIN_HIGH_PW, 64); |
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| 194 | int max_high = TIME_MICROS(MAX_HIGH_PW, 64); |
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| 195 | 63e19141 | Tom Mullins | |
| 196 | 31f4a032 | Tom Mullins | if (rx->count) {
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| 197 | 399f7d1b | Tom Mullins | int diff = (now - rx->last_time);
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| 198 | 31f4a032 | Tom Mullins | rx->bits <<= 1;
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| 199 | 399f7d1b | Tom Mullins | if (min_low < diff && diff < max_low) {
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| 200 | 31f4a032 | Tom Mullins | // 0 already in bits
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| 201 | 399f7d1b | Tom Mullins | } else if (min_high < diff && diff < max_high) { |
| 202 | 31f4a032 | Tom Mullins | // add 1 to bits
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| 203 | rx->bits |= 1;
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| 204 | } else {
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| 205 | // error, start from beginning
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| 206 | rx->count = 0;
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| 207 | rx->bits = 0;
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| 208 | } |
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| 209 | if (rx->count == 16) { |
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| 210 | // finished!
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| 211 | 69c2203a | Tom Mullins | if ((rx->bits & 3) == 2) { // expansion and check bits |
| 212 | 31f4a032 | Tom Mullins | rx->data = (rx->bits >> 2) & 0xff; |
| 213 | rx->address = (rx->bits >> 10) & 0x1f; |
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| 214 | rx->new_data = 1;
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| 215 | 69c2203a | Tom Mullins | } |
| 216 | 31f4a032 | Tom Mullins | rx->count = 0;
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| 217 | rx->bits = 0;
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| 218 | f115416e | Tom Mullins | } |
| 219 | } |
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| 220 | 63e19141 | Tom Mullins | |
| 221 | 31f4a032 | Tom Mullins | rx->count++; |
| 222 | rx->last_time = now; |
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| 223 | f115416e | Tom Mullins | } |
| 224 | } |
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| 225 | |||
| 226 | ISR(PCINT0_vect) {
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| 227 | cc9ca04e | Tom Mullins | uint8_t bom_sig = PIN_BOM_SIG; |
| 228 | f115416e | Tom Mullins | uint8_t changed = bom_sig ^ prev_bom_sig; |
| 229 | cc9ca04e | Tom Mullins | if (changed & _BV(P_BOM_SIG0)) recv_edge(bom_sig & _BV(P_BOM_SIG0), &bom_rx[0]); |
| 230 | if (changed & _BV(P_BOM_SIG1)) recv_edge(bom_sig & _BV(P_BOM_SIG1), &bom_rx[1]); |
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| 231 | if (changed & _BV(P_BOM_SIG2)) recv_edge(bom_sig & _BV(P_BOM_SIG2), &bom_rx[2]); |
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| 232 | if (changed & _BV(P_BOM_SIG3)) recv_edge(bom_sig & _BV(P_BOM_SIG3), &bom_rx[3]); |
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| 233 | f115416e | Tom Mullins | prev_bom_sig = bom_sig; |
| 234 | } |
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| 235 | |||
| 236 | int bom_get(char dir) { |
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| 237 | bom_rx_t *rx = &bom_rx[(int)dir];
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| 238 | int ret = BOM_NO_DATA;
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| 239 | cli(); |
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| 240 | if (rx->new_data) {
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| 241 | rx->new_data = 0;
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| 242 | ret = rx->data; |
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| 243 | } |
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| 244 | sei(); |
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| 245 | return ret;
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| 246 | } |