| 1 | /****************************************************************************** |
| 2 | * |
| 3 | * Trennfix firmware - mm_switch.c |
| 4 | * |
| 5 | * Maerklin Motorola switch command receiver |
| 6 | * |
| 7 | * Copyright (C) 2017 Philipp Hachtmann |
| 8 | * |
| 9 | * This program is free software: you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License as published by |
| 11 | * the Free Software Foundation, either version 3 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This program is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | * GNU General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License |
| 20 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 21 | * |
| 22 | *****************************************************************************/ |
| 23 | |
| 24 | #include <stdio.h> |
| 25 | #include <stdlib.h> |
| 26 | #include <string.h> |
| 27 | |
| 28 | #include <avr/io.h> |
| 29 | #include <avr/eeprom.h> |
| 30 | #include <avr/interrupt.h> |
| 31 | #include <avr/pgmspace.h> |
| 32 | |
| 33 | #include <util/delay.h> |
| 34 | #include <stdint.h> |
| 35 | |
| 36 | #include "hardware.h" |
| 37 | #include "mm_switch.h" |
| 38 | |
| 39 | #define DEBUG_TIMEOUT |
| 40 | #ifdef DEBUG_TIMEOUT |
| 41 | #define MON(val) setpin(PIN_DRIVE, val) |
| 42 | #else |
| 43 | #define MON(xx) ({0;}) |
| 44 | #endif |
| 45 | |
| 46 | |
| 47 | /* |
| 48 | * Lookup decoder number. |
| 49 | * |
| 50 | */ |
| 51 | static uint8_t lookup_decoder(uint8_t mm_byte) |
| 52 | { |
| 53 | switch(mm_byte) { |
| 54 | /* 0x00 is invalid */ |
| 55 | case 0xc0: return 1; |
| 56 | case 0x80: return 2; |
| 57 | case 0x30: return 3; |
| 58 | case 0xf0: return 4; |
| 59 | case 0xb0: return 5; |
| 60 | case 0x20: return 6; |
| 61 | case 0xe0: return 7; |
| 62 | case 0xa0: return 8; |
| 63 | |
| 64 | case 0x0c: return 9; |
| 65 | case 0xcc: return 10; |
| 66 | case 0x8c: return 11; |
| 67 | case 0x3c: return 12; |
| 68 | case 0xfc: return 13; |
| 69 | case 0xbc: return 14; |
| 70 | case 0x2c: return 15; |
| 71 | case 0xec: return 16; |
| 72 | case 0xac: return 17; |
| 73 | |
| 74 | case 0x08: return 18; |
| 75 | case 0xc8: return 19; |
| 76 | case 0x88: return 20; |
| 77 | case 0x38: return 21; |
| 78 | case 0xf8: return 22; |
| 79 | case 0xb8: return 23; |
| 80 | case 0x28: return 24; |
| 81 | case 0xe8: return 25; |
| 82 | |
| 83 | default: |
| 84 | return 0; |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | static uint8_t lookup_command(uint8_t mm_byte) |
| 89 | { |
| 90 | switch(mm_byte) { |
| 91 | case 0xc3: return 1; |
| 92 | case 0x03: return 2; |
| 93 | case 0xf3: return 3; |
| 94 | case 0x33: return 4; |
| 95 | case 0xcf: return 5; |
| 96 | case 0x0f: return 6; |
| 97 | case 0xff: return 7; |
| 98 | case 0x3f: return 8; |
| 99 | default: |
| 100 | return 0; |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | static void mm_switch_init(void) |
| 105 | { |
| 106 | /* Get rid of the 1/8 clock prescaler */ |
| 107 | CLKPR = (1 << CLKPCE); |
| 108 | CLKPR = 0; |
| 109 | |
| 110 | GIMSK |= _BV(PCIE); /* Enable pin change interrupt */ |
| 111 | PCMSK = _BV(PCINT4); /* PB4, Rail sense input */ |
| 112 | |
| 113 | TCCR0A = 0; /* This is normal mode */ |
| 114 | TCCR0B = 0; /* Timer off */ |
| 115 | TIMSK |= _BV(OCIE0A); /* Get a match interrupt */ |
| 116 | TIMSK |= _BV(TOV0); /* Overflow interrupt */ |
| 117 | |
| 118 | /* We need 13 + 45 us delay, That's 464 clocks @8MHz*/ |
| 119 | OCR0A = 91; /* Prescaler 8 is used */ |
| 120 | |
| 121 | /* Timer 1 for timeout */ |
| 122 | /* We set it to 1024us by prescaler 64 and running full 256 */ |
| 123 | TCCR1 = 7; |
| 124 | TIMSK |= _BV(TOIE1); /* Overflow interrupt */ |
| 125 | } |
| 126 | |
| 127 | |
| 128 | static volatile uint8_t shift_sub; |
| 129 | static volatile uint8_t shift_zero; |
| 130 | static volatile uint8_t shift_decoder; |
| 131 | static volatile uint8_t shift_sub_first; |
| 132 | static volatile uint8_t shift_decoder_first; |
| 133 | |
| 134 | /* We will shift from right to left. |
| 135 | * XXXXXXXX XX XXXXXXXX |
| 136 | * shift_decoder shift_zero shift_sub |
| 137 | * |
| 138 | * The bits 7 downto 2 of shift_zero are ignored. |
| 139 | */ |
| 140 | |
| 141 | volatile uint8_t bitno = 0; |
| 142 | |
| 143 | static void trigger(void) |
| 144 | { |
| 145 | setpin(PIN_DRIVE, 1); |
| 146 | _delay_us(10); |
| 147 | setpin(PIN_DRIVE, 0); |
| 148 | } |
| 149 | |
| 150 | enum recstate { |
| 151 | IDLE = 0, |
| 152 | FIRST_FAST_SAMPLE, |
| 153 | FIRST_SLOW_SAMPLE, /* If clock arrives, we stay on the fast path! */ |
| 154 | FAST_SAMPLE, |
| 155 | FAST_WAIT_FOR_CLOCK, |
| 156 | SLOW_SAMPLE, |
| 157 | SLOW_WAIT_FOR_CLOCK, |
| 158 | }; |
| 159 | |
| 160 | static enum recstate recstate = IDLE; |
| 161 | |
| 162 | static inline void shift(uint8_t value) |
| 163 | { |
| 164 | shift_decoder <<= 1; |
| 165 | if (shift_zero & 2) |
| 166 | shift_decoder |= 1; |
| 167 | shift_zero <<= 1; |
| 168 | if (shift_sub & 0x80) |
| 169 | shift_zero |= 1; |
| 170 | shift_sub <<= 1; |
| 171 | if (value) |
| 172 | shift_sub |= 1; |
| 173 | } |
| 174 | |
| 175 | |
| 176 | ISR(TIMER0_COMPA_vect) { |
| 177 | |
| 178 | static uint8_t patience = 0; |
| 179 | |
| 180 | switch(recstate) { |
| 181 | case FIRST_FAST_SAMPLE: |
| 182 | recstate = FIRST_SLOW_SAMPLE; |
| 183 | TSTART_CLK_TO_SAMPLE_FAST; /* Will not run out in fast! */ |
| 184 | break; |
| 185 | |
| 186 | case FIRST_SLOW_SAMPLE: |
| 187 | bitno = 0; |
| 188 | |
| 189 | case SLOW_SAMPLE: |
| 190 | recstate = SLOW_WAIT_FOR_CLOCK; |
| 191 | TSTART_CLK_TO_SAMPLE_SLOW; |
| 192 | break; |
| 193 | |
| 194 | case FAST_SAMPLE: |
| 195 | recstate = FAST_WAIT_FOR_CLOCK; |
| 196 | TSTART_CLK_TO_SAMPLE_FAST; |
| 197 | break; |
| 198 | |
| 199 | case FAST_WAIT_FOR_CLOCK: /* A timeout! */ |
| 200 | if (patience) { |
| 201 | patience--; |
| 202 | TSTART_CLK_TO_SAMPLE_FAST; |
| 203 | return; |
| 204 | } |
| 205 | recstate = IDLE; |
| 206 | TSTOP; |
| 207 | return; |
| 208 | |
| 209 | case SLOW_WAIT_FOR_CLOCK: |
| 210 | if (patience) { |
| 211 | patience--; |
| 212 | TSTART_CLK_TO_SAMPLE_SLOW; |
| 213 | return; |
| 214 | } |
| 215 | TSTOP; |
| 216 | recstate = IDLE; |
| 217 | return; |
| 218 | } |
| 219 | |
| 220 | shift(MM_SENSE); |
| 221 | bitno++; |
| 222 | |
| 223 | if (bitno == 18) { /* Save first received word */ |
| 224 | shift_sub_first = shift_sub; |
| 225 | shift_decoder_first = shift_decoder; |
| 226 | patience = 18; |
| 227 | |
| 228 | } |
| 229 | if (bitno == 36) { |
| 230 | if ((shift_sub == shift_sub_first) && |
| 231 | (shift_decoder == shift_decoder_first)) { |
| 232 | uint8_t decoder = lookup_decoder(shift_decoder); |
| 233 | uint8_t command = lookup_command(shift_sub); |
| 234 | if (recstate == SLOW_WAIT_FOR_CLOCK) |
| 235 | trigger(); |
| 236 | if (decoder) { |
| 237 | /* Congratulations, we have a valid command */ |
| 238 | if (recstate == FAST_WAIT_FOR_CLOCK) { |
| 239 | // trigger(); |
| 240 | mm_switch_command(decoder, command); |
| 241 | } |
| 242 | } |
| 243 | } |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | ISR(BADISR_vect) |
| 248 | { |
| 249 | while(1) { |
| 250 | /* |
| 251 | setpin(PIN_LED, 1); |
| 252 | _delay_ms(30); |
| 253 | setpin(PIN_LED, 0); |
| 254 | _delay_ms(30); |
| 255 | setpin(PIN_LED, 1); |
| 256 | _delay_ms(30); |
| 257 | setpin(PIN_LED, 0); |
| 258 | _delay_ms(2000); |
| 259 | */ |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | ISR(TIM0_OVF_vect) |
| 264 | { |
| 265 | return; |
| 266 | while(1) { |
| 267 | setpin(PIN_LED, 1); |
| 268 | _delay_ms(30); |
| 269 | setpin(PIN_LED, 0); |
| 270 | _delay_ms(300); |
| 271 | } |
| 272 | |
| 273 | } |
| 274 | |
| 275 | |
| 276 | /* Pin change interrupt vector */ |
| 277 | void mm_pinchange_handler(void) |
| 278 | { |
| 279 | static uint8_t sense_last; |
| 280 | |
| 281 | if (MM_SENSE == sense_last) |
| 282 | return; |
| 283 | sense_last = MM_SENSE; |
| 284 | if (!sense_last) |
| 285 | return; |
| 286 | |
| 287 | switch(recstate) { |
| 288 | case IDLE: |
| 289 | bitno = 0; |
| 290 | recstate = FIRST_FAST_SAMPLE; |
| 291 | TSTART_CLK_TO_SAMPLE_FAST; |
| 292 | break; |
| 293 | case FIRST_SLOW_SAMPLE: |
| 294 | recstate = FAST_SAMPLE; |
| 295 | TSTART_CLK_TO_SAMPLE_FAST; |
| 296 | break; |
| 297 | case FAST_WAIT_FOR_CLOCK: |
| 298 | recstate = FAST_SAMPLE; |
| 299 | TSTART_CLK_TO_SAMPLE_FAST; |
| 300 | break; |
| 301 | case SLOW_WAIT_FOR_CLOCK: |
| 302 | recstate = SLOW_SAMPLE; |
| 303 | TSTART_CLK_TO_SAMPLE_SLOW; |
| 304 | break; |
| 305 | |
| 306 | /* Not expected */ |
| 307 | case FIRST_FAST_SAMPLE: |
| 308 | case FAST_SAMPLE: |
| 309 | case SLOW_SAMPLE: |
| 310 | default: |
| 311 | break; |
| 312 | } |
| 313 | } |
| 314 | |
| 315 | /****************************************************************************** |
| 316 | * The end :-) |
| 317 | */ |
| 318 | |
| 319 | |
| 320 | |