| 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 <config/hardware.h> |
| 37 | #include <mm/mm_switch.h> |
| 38 | #include <mm/mm_decode.h> |
| 39 | |
| 40 | /* |
| 41 | * |
| 42 | * Check for stuff we need |
| 43 | * |
| 44 | */ |
| 45 | #if !defined(MM_TSTART) || !defined(MM_SENSE) || !defined(MM_TIMER_INT_VECT) |
| 46 | #error Missing needed MM_... macro! |
| 47 | #endif |
| 48 | |
| 49 | #ifndef MM_QUEUE_DEPTH |
| 50 | #define MM_QUEUE_DEPTH 8 |
| 51 | #endif |
| 52 | |
| 53 | |
| 54 | /* |
| 55 | * The nominal length of a bit cycle is 208 us. |
| 56 | * This consists of 8 parts, each 26 us: |
| 57 | * 1 d d d d d d 0 |
| 58 | * |
| 59 | * That means that the 1 pulse is 7 * 26 = 182us |
| 60 | * and the short pulse is 1 * 26 = 26us. |
| 61 | * |
| 62 | * Reality seems to look not as that exact. I measure |
| 63 | * 26us for the clock pulse, but 196 for the long pulse. |
| 64 | * |
| 65 | * Keep in mind: Time is counted in 500ns steps. |
| 66 | * |
| 67 | */ |
| 68 | #define IN_RANGE(duration, lower, upper) \ |
| 69 | ((duration >= (2 * lower) \ |
| 70 | && (duration <= (2 * upper)))) |
| 71 | |
| 72 | #define MM_FAST_SHORT(duration) IN_RANGE(duration, 7, 18) |
| 73 | #define MM_FAST_LONG(duration) IN_RANGE(duration, 70, 130) |
| 74 | #define MM_FAST_GAP(duration) IN_RANGE(duration, 500, 1100) |
| 75 | |
| 76 | #define MM_SLOW_SHORT(duration) IN_RANGE(duration, 18, 35) |
| 77 | #define MM_SLOW_LONG(duration) IN_RANGE(duration, 150, 210) |
| 78 | #define MM_SLOW_GAP(duration) IN_RANGE(duration, 1000, 2000) |
| 79 | |
| 80 | #define MM_SUFFICIENT_IDLE(duration) (duration > 800) |
| 81 | |
| 82 | |
| 83 | |
| 84 | static enum mm_recmode recmode = __MM_INIT; |
| 85 | |
| 86 | #ifdef MM_USE_QUEUE |
| 87 | static uint8_t queue_wpos = 0; |
| 88 | static uint8_t queue_rpos = 0; |
| 89 | static struct mm_command queue[MM_QUEUE_DEPTH]; |
| 90 | #endif |
| 91 | |
| 92 | #ifndef MM_USE_REGISTER_VARS |
| 93 | |
| 94 | static volatile uint8_t mm_bitno = 0; |
| 95 | static uint8_t shift_command; |
| 96 | static uint8_t shift_function; |
| 97 | static uint8_t shift_address; |
| 98 | uint8_t mm_time_h = 0; |
| 99 | uint8_t mm_time_l = 0; |
| 100 | uint8_t mm_bit_val = 23; |
| 101 | static uint8_t mm_flavor; |
| 102 | static uint8_t mm_polarity = 1; |
| 103 | |
| 104 | #endif |
| 105 | |
| 106 | /* We will shift from right to left. |
| 107 | * XXXXXXXX XX XXXXXXXX |
| 108 | * shift_address shift_function shift_command |
| 109 | * |
| 110 | * The bits 7 downto 2 of shift_function are ignored. |
| 111 | * |
| 112 | * First comes the C implementation of the shift routine. |
| 113 | * It is usually not used anymore, but I left it for |
| 114 | * illustration purposes. |
| 115 | * The real shift function is written in assembly and saves many instructions. |
| 116 | */ |
| 117 | #if 0 |
| 118 | static void shift(uint8_t value) |
| 119 | { |
| 120 | shift_address <<= 1; |
| 121 | if (shift_function & 2) |
| 122 | shift_address |= 1; |
| 123 | shift_function <<= 1; |
| 124 | if (shift_command & 0x80) |
| 125 | shift_function |= 1; |
| 126 | shift_command <<= 1; |
| 127 | if (value) |
| 128 | shift_command |= 1; |
| 129 | } |
| 130 | #else |
| 131 | |
| 132 | static void shift(uint8_t value) |
| 133 | { |
| 134 | asm("ror %[val] ; Shift value right into carry\n\t" |
| 135 | "rol %[cmd] ; and shift to command reg\n\t" |
| 136 | "mov __tmp_reg__, %[func] ; save function value \n\t" |
| 137 | "rol %[func] ; Shift up function value\n\t" |
| 138 | "ror __tmp_reg__ ; shift bit 1\n\t" |
| 139 | "ror __tmp_reg__ ; down to carry\n\t" |
| 140 | "rol %[addr] ; And we're at the address\n\t" |
| 141 | : [cmd] "=r" (shift_command), [func] "=r" (shift_function), |
| 142 | [addr] "=r" (shift_address) |
| 143 | : "0" (shift_command), "1" (shift_function), |
| 144 | "2" (shift_address), [val] "r" (value) |
| 145 | ); |
| 146 | } |
| 147 | #endif |
| 148 | |
| 149 | static void mm_feed_bit(uint8_t bit) |
| 150 | { |
| 151 | static volatile uint8_t shift_command_first; |
| 152 | static volatile uint8_t shift_function_first; |
| 153 | static volatile uint8_t shift_address_first; |
| 154 | uint8_t address; |
| 155 | |
| 156 | shift(bit); |
| 157 | mm_bitno++; |
| 158 | |
| 159 | if (mm_bitno == 18) { /* Save first received word */ |
| 160 | shift_address_first = shift_address; |
| 161 | shift_function_first = shift_function; |
| 162 | shift_command_first = shift_command; |
| 163 | } |
| 164 | |
| 165 | if (mm_bitno == 36) { |
| 166 | if ((shift_command == shift_command_first) && |
| 167 | (shift_address == shift_address_first) && |
| 168 | (shift_function == shift_function_first)) { |
| 169 | |
| 170 | #ifdef MM_USE_CALLBACK |
| 171 | address = mm_lookup_decoder(shift_address); |
| 172 | if (recmode == MM_SLOW) { |
| 173 | mm_drive_cb(address, shift_function, |
| 174 | shift_command); |
| 175 | } else { |
| 176 | mm_key_cb(address, shift_function, shift_command); |
| 177 | } |
| 178 | #endif |
| 179 | |
| 180 | #ifdef MM_USE_QUEUE |
| 181 | queue[queue_wpos].recmode = recmode; |
| 182 | queue[queue_wpos].address = shift_address; |
| 183 | queue[queue_wpos].function = shift_function; |
| 184 | queue[queue_wpos].command = shift_command; |
| 185 | queue_wpos = (queue_wpos + 1) % MM_QUEUE_DEPTH; |
| 186 | #endif |
| 187 | } |
| 188 | } |
| 189 | } |
| 190 | #ifdef MM_USE_QUEUE |
| 191 | |
| 192 | struct mm_command *mm_get(void) |
| 193 | { |
| 194 | struct mm_command *result = NULL; |
| 195 | uint8_t sreg_bak = SREG; |
| 196 | cli(); |
| 197 | if (queue_rpos != queue_wpos) { |
| 198 | result = &queue[queue_rpos]; |
| 199 | queue_rpos = (queue_rpos + 1) % MM_QUEUE_DEPTH; |
| 200 | } |
| 201 | SREG = sreg_bak; |
| 202 | return result; |
| 203 | } |
| 204 | #endif |
| 205 | |
| 206 | /* |
| 207 | * The timeout interrupt vector does nothing else |
| 208 | * than incrementing the mm_time_h round counter. |
| 209 | * |
| 210 | * It is written in naked assembly because we want to avoid pushing |
| 211 | * and popping of all upper registers. |
| 212 | */ |
| 213 | void __attribute__((naked)) MM_TIMER_INT_VECT(void) |
| 214 | { |
| 215 | asm("push r0 ; save r0 \n\t" |
| 216 | "in r0, __SREG__ \n\t" |
| 217 | #ifdef MM_USE_REGISTER_VARS |
| 218 | "inc %[th] \n\t" |
| 219 | "brne nover \n\t" |
| 220 | "dec %[th] \n\t" |
| 221 | "nover: \n\t" |
| 222 | #else |
| 223 | "push r1 \n\t" |
| 224 | "lds r1, mm_time_h \n\t" |
| 225 | "inc r1 \n\t" |
| 226 | "brne nover \n\t" |
| 227 | "dec r1 \n\t" |
| 228 | "nover: \n\t" |
| 229 | "sts mm_time_h, r1 \n\t" |
| 230 | "pop r1 \n\t" |
| 231 | #endif |
| 232 | "out __SREG__, r0 \n\t" |
| 233 | "pop r0 \n\t" |
| 234 | "reti \n\t" |
| 235 | #ifdef MM_USE_REGISTER_VARS |
| 236 | :: [th] "r" (mm_time_h) |
| 237 | #endif |
| 238 | ); |
| 239 | } |
| 240 | |
| 241 | /* |
| 242 | * Another naked interrupt trampoline |
| 243 | * |
| 244 | * Here we first save the timer value as fast as possible, then we jump (!) |
| 245 | * into the "official" interrupt handler with all its decorations. |
| 246 | */ |
| 247 | void __attribute__((naked)) PCINT0_vect(void) |
| 248 | { |
| 249 | #ifdef MM_USE_REGISTER_VARS |
| 250 | asm("in %[tl], %[tmr] \n\t" |
| 251 | "rjmp __vector_pinchange \n\t" |
| 252 | :: [tl] "r" (mm_time_l), [tmr] "I" (_SFR_IO_ADDR(TCNT0)) |
| 253 | ); |
| 254 | #else |
| 255 | asm("push r0 \n\t" |
| 256 | "in r0, %[tmr] \n\t" |
| 257 | "sts mm_time_l, r0 \n\t" |
| 258 | "pop r0 \n\t" |
| 259 | "rjmp __vector_pinchange \n\t" |
| 260 | :: [tmr] "I" (_SFR_IO_ADDR(TCNT0)) |
| 261 | ); |
| 262 | #endif |
| 263 | } |
| 264 | |
| 265 | /* Pin change interrupt vector, here we have a bit more time */ |
| 266 | ISR(__vector_pinchange){ |
| 267 | uint16_t duration; |
| 268 | |
| 269 | /* First kill off that timer */ |
| 270 | MM_TSTART; /* Restart timer */ |
| 271 | |
| 272 | /* Account for not yet handled timer overflow */ |
| 273 | TIFR |= _BV(TOV0); |
| 274 | |
| 275 | duration = mm_time_h << 8; |
| 276 | duration += mm_time_l; |
| 277 | mm_bit_val = MM_SENSE; |
| 278 | mm_time_h = 0; |
| 279 | |
| 280 | if (recmode != MM_SLOW) { |
| 281 | /* Fast short MM pulse */ |
| 282 | if (MM_FAST_SHORT(duration)){ |
| 283 | recmode = MM_FAST; |
| 284 | if (mm_bit_val == mm_polarity) |
| 285 | mm_feed_bit(0); |
| 286 | goto done; |
| 287 | } |
| 288 | /* Fast long MM pulse */ |
| 289 | if (MM_FAST_LONG(duration)) { |
| 290 | recmode = MM_FAST; |
| 291 | if (mm_bit_val == mm_polarity) |
| 292 | mm_feed_bit(1); |
| 293 | goto done; |
| 294 | } |
| 295 | } else { |
| 296 | /* Accepted slow inter package gap */ |
| 297 | if (MM_SLOW_GAP(duration)) |
| 298 | if (mm_bit_val != mm_polarity) |
| 299 | goto done; |
| 300 | } |
| 301 | |
| 302 | if (recmode != MM_FAST) { |
| 303 | |
| 304 | /* Slow short MM pulse */ |
| 305 | if (MM_SLOW_SHORT(duration)) { |
| 306 | recmode = MM_SLOW; |
| 307 | if (mm_bit_val == mm_polarity) |
| 308 | mm_feed_bit(0); |
| 309 | goto done; |
| 310 | } |
| 311 | /* Slow long MM pulse */ |
| 312 | if (MM_SLOW_LONG(duration)) { |
| 313 | recmode = MM_SLOW; |
| 314 | if (mm_bit_val == mm_polarity) |
| 315 | mm_feed_bit(1); |
| 316 | goto done; |
| 317 | } |
| 318 | } else { |
| 319 | /* Accepted fast interpackage gap */ |
| 320 | if (MM_FAST_GAP(duration)) { |
| 321 | if (mm_bit_val != mm_polarity) |
| 322 | goto done; |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | /* |
| 327 | * If we have reached here, our pulse comes in somehow unexpected. |
| 328 | * We kill of everything by re-arming the state machine. |
| 329 | */ |
| 330 | /* Start over receiver */ |
| 331 | mm_bitno = 0; |
| 332 | |
| 333 | if (MM_SUFFICIENT_IDLE(duration)) { |
| 334 | recmode = __MM_ARMED; |
| 335 | mm_polarity = !mm_bit_val; |
| 336 | } else { |
| 337 | recmode = __MM_INIT; |
| 338 | } |
| 339 | done: |
| 340 | mm_pinchange_callback(); |
| 341 | } |
| 342 | |
| 343 | |
| 344 | void __attribute__((weak))mm_pinchange_callback(void) |
| 345 | { |
| 346 | } |
| 347 | |
| 348 | void __attribute__((weak))mm_drive_cb(uint8_t decoder, uint8_t function, |
| 349 | uint8_t command) |
| 350 | { |
| 351 | } |
| 352 | |
| 353 | void __attribute__((weak))mm_key_cb(uint8_t address, uint8_t function, |
| 354 | uint8_t command) |
| 355 | { |
| 356 | } |
| 357 | |
| 358 | |
| 359 | /****************************************************************************** |
| 360 | * The end :-) |
| 361 | */ |