root / scout_avr / src / bom.cpp @ cc9ca04e
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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 | #define TIME_MICROS(us, prescale) (F_CPU / 1000000 * (us) / (prescale)) |
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| 19 | |||
| 20 | typedef uint16_t sharp_msg_t;
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| 21 | |||
| 22 | static sharp_msg_t sharp_msg_make(char address, bom_msg_t bom_msg) { |
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| 23 | return (((uint16_t)address & 0x3F) << 10) | ((uint16_t)bom_msg << 2) | 2; |
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| 24 | } |
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| 25 | |||
| 26 | static char robot_id; |
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| 27 | |||
| 28 | // tx global vars
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| 29 | static sharp_msg_t out_msg;
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| 30 | static uint8_t out_pin_mask;
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| 31 | static char out_high, out_counter; |
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| 32 | static volatile char out_done; |
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| 33 | |||
| 34 | // rx global vars
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| 35 | static uint8_t prev_bom_sig;
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| 36 | static struct bom_rx_t { |
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| 37 | 31f4a032 | Tom Mullins | uint8_t count; |
| 38 | f115416e | Tom Mullins | uint16_t bits; |
| 39 | 31f4a032 | Tom Mullins | int last_time;
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| 40 | f115416e | Tom Mullins | |
| 41 | uint8_t new_data; |
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| 42 | uint8_t address; |
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| 43 | uint8_t data; |
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| 44 | } bom_rx[4];
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| 45 | |||
| 46 | void set_robot_id(char id) { |
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| 47 | robot_id = id; |
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| 48 | } |
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| 49 | |||
| 50 | char get_robot_id(void) { |
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| 51 | return robot_id;
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| 52 | } |
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| 53 | |||
| 54 | 812788aa | Tom Mullins | void bom_isr() {
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| 55 | f115416e | Tom Mullins | if (out_high) {
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| 56 | cc9ca04e | Tom Mullins | PORT_BOM_EMIT ^= out_pin_mask; |
| 57 | f115416e | Tom Mullins | } |
| 58 | } |
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| 59 | |||
| 60 | static void init_38kHz_signal() { |
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| 61 | out_high = 0;
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| 62 | out_pin_mask = 0;
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| 63 | |||
| 64 | 812788aa | Tom Mullins | // timer configuration now done in Atmega128rfa1.cpp
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| 65 | f115416e | Tom Mullins | } |
| 66 | |||
| 67 | static void start_38kHz_signal() { |
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| 68 | TCNT3 = 0;
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| 69 | cc9ca04e | Tom Mullins | PORT_BOM_EMIT |= out_pin_mask; |
| 70 | f115416e | Tom Mullins | out_high = 1;
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| 71 | } |
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| 72 | |||
| 73 | static void stop_38kHz_signal() { |
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| 74 | cc9ca04e | Tom Mullins | PORT_BOM_EMIT &= ~ out_pin_mask; |
| 75 | f115416e | Tom Mullins | out_high = 0;
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| 76 | } |
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| 77 | |||
| 78 | static void init_data_signal() { |
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| 79 | // timer 4 mode CTC (clear timer on compare), TOP = OCRA
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| 80 | TCCR4A = 0;
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| 81 | TCCR4B = _BV(WGM42); |
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| 82 | |||
| 83 | // run interrupt immediately when timer started
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| 84 | OCR4A = 0;
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| 85 | |||
| 86 | // enable interrupt
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| 87 | TIMSK4 = _BV(OCIE4A); |
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| 88 | } |
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| 89 | |||
| 90 | static void start_data_signal() { |
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| 91 | TCNT4 = 0;
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| 92 | |||
| 93 | // start timer 4 at F_CPU/64 prescaling
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| 94 | TCCR4B |= _BV(CS41) | _BV(CS40); |
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| 95 | } |
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| 96 | |||
| 97 | static void stop_data_signal() { |
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| 98 | // stop timer 4
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| 99 | TCCR4B &= ~ (_BV(CS42) | _BV(CS41) | _BV(CS40)); |
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| 100 | } |
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| 101 | |||
| 102 | ISR(TIMER4_COMPA_vect) {
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| 103 | 31f4a032 | Tom Mullins | if (out_high) {
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| 104 | stop_38kHz_signal(); |
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| 105 | if (out_counter) {
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| 106 | out_counter--; |
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| 107 | if ((out_msg >> out_counter) & 1) { |
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| 108 | f115416e | Tom Mullins | OCR4A = TIME_MICROS(1680, 64); |
| 109 | } else {
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| 110 | OCR4A = TIME_MICROS(680, 64); |
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| 111 | } |
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| 112 | } else {
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| 113 | 31f4a032 | Tom Mullins | stop_data_signal(); |
| 114 | out_done = 1;
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| 115 | f115416e | Tom Mullins | } |
| 116 | } else {
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| 117 | 31f4a032 | Tom Mullins | start_38kHz_signal(); |
| 118 | OCR4A = TIME_MICROS(320, 64); |
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| 119 | f115416e | Tom Mullins | } |
| 120 | } |
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| 121 | |||
| 122 | void bom_init(void) { |
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| 123 | // BOM_SIG as input, interrupts enabled
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| 124 | DDRB &= ~ (_BV(DDB0) | _BV(DDB1) | _BV(DDB2) | _BV(DDB3)); |
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| 125 | PCMSK0 |= _BV(PCINT0) | _BV(PCINT1) | _BV(PCINT2) | _BV(PCINT3); |
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| 126 | PCICR |= _BV(PCIE0); |
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| 127 | |||
| 128 | // BOM_EMIT as output
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| 129 | cc9ca04e | Tom Mullins | DDRF |= _BV(DDF4) | _BV(DDF5) | _BV(DDF6) | _BV(DDF7); |
| 130 | f115416e | Tom Mullins | |
| 131 | init_38kHz_signal(); |
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| 132 | init_data_signal(); |
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| 133 | } |
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| 134 | |||
| 135 | void bom_send(char dir) { |
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| 136 | switch (dir) {
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| 137 | cc9ca04e | Tom Mullins | case BOM_FRONT: out_pin_mask = _BV(P_BOM_EMIT0); break; |
| 138 | case BOM_LEFT: out_pin_mask = _BV(P_BOM_EMIT1); break; |
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| 139 | case BOM_RIGHT: out_pin_mask = _BV(P_BOM_EMIT2); break; |
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| 140 | case BOM_BACK: out_pin_mask = _BV(P_BOM_EMIT3); break; |
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| 141 | f115416e | Tom Mullins | } |
| 142 | 31f4a032 | Tom Mullins | out_counter = 16;
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| 143 | f115416e | Tom Mullins | out_msg = sharp_msg_make(0x2A, bom_msg_make(robot_id, dir));
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| 144 | out_done = 0;
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| 145 | start_data_signal(); |
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| 146 | while (!out_done) {
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| 147 | _delay_ms(0.1); |
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| 148 | } |
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| 149 | } |
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| 150 | |||
| 151 | static void recv_edge(char is_rising, struct bom_rx_t *rx) { |
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| 152 | if (is_rising) {
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| 153 | 31f4a032 | Tom Mullins | // TODO check 320us? or have 320us timeout on rising edge?
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| 154 | } else {
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| 155 | 812788aa | Tom Mullins | // uses timer 5, assuming prescale 1/8
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| 156 | // timer 5 is set up by range_init()
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| 157 | 31f4a032 | Tom Mullins | // this should be in units of microseconds
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| 158 | 812788aa | Tom Mullins | int now = TCNT5 / (F_CPU / 8 / 1000000); |
| 159 | 31f4a032 | Tom Mullins | |
| 160 | if (rx->count) {
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| 161 | int diff = now - rx->last_time;
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| 162 | rx->bits <<= 1;
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| 163 | if (MIN_LOW_PW < diff && diff < MAX_LOW_PW) {
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| 164 | // 0 already in bits
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| 165 | } else if (MIN_HIGH_PW < diff && diff < MAX_HIGH_PW) { |
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| 166 | // add 1 to bits
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| 167 | rx->bits |= 1;
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| 168 | } else {
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| 169 | // error, start from beginning
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| 170 | rx->count = 0;
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| 171 | rx->bits = 0;
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| 172 | } |
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| 173 | if (rx->count == 16) { |
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| 174 | // finished!
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| 175 | 69c2203a | Tom Mullins | if ((rx->bits & 3) == 2) { // expansion and check bits |
| 176 | 31f4a032 | Tom Mullins | rx->data = (rx->bits >> 2) & 0xff; |
| 177 | rx->address = (rx->bits >> 10) & 0x1f; |
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| 178 | rx->new_data = 1;
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| 179 | 69c2203a | Tom Mullins | } |
| 180 | 31f4a032 | Tom Mullins | rx->count = 0;
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| 181 | rx->bits = 0;
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| 182 | f115416e | Tom Mullins | } |
| 183 | } |
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| 184 | 31f4a032 | Tom Mullins | |
| 185 | rx->count++; |
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| 186 | rx->last_time = now; |
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| 187 | f115416e | Tom Mullins | } |
| 188 | } |
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| 189 | |||
| 190 | ISR(PCINT0_vect) {
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| 191 | cc9ca04e | Tom Mullins | uint8_t bom_sig = PIN_BOM_SIG; |
| 192 | f115416e | Tom Mullins | uint8_t changed = bom_sig ^ prev_bom_sig; |
| 193 | cc9ca04e | Tom Mullins | if (changed & _BV(P_BOM_SIG0)) recv_edge(bom_sig & _BV(P_BOM_SIG0), &bom_rx[0]); |
| 194 | if (changed & _BV(P_BOM_SIG1)) recv_edge(bom_sig & _BV(P_BOM_SIG1), &bom_rx[1]); |
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| 195 | if (changed & _BV(P_BOM_SIG2)) recv_edge(bom_sig & _BV(P_BOM_SIG2), &bom_rx[2]); |
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| 196 | if (changed & _BV(P_BOM_SIG3)) recv_edge(bom_sig & _BV(P_BOM_SIG3), &bom_rx[3]); |
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| 197 | f115416e | Tom Mullins | prev_bom_sig = bom_sig; |
| 198 | } |
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| 199 | |||
| 200 | int bom_get(char dir) { |
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| 201 | bom_rx_t *rx = &bom_rx[(int)dir];
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| 202 | int ret = BOM_NO_DATA;
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| 203 | cli(); |
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| 204 | if (rx->new_data) {
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| 205 | rx->new_data = 0;
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| 206 | ret = rx->data; |
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| 207 | } |
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| 208 | sei(); |
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| 209 | return ret;
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| 210 | } |