--- /dev/null
+/******************************************************************************
+ *
+ * Trennfix firmware - mm_switch.c
+ *
+ * Maerklin Motorola switch command receiver
+ *
+ * Copyright (C) 2017 Philipp Hachtmann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ *****************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <avr/io.h>
+#include <avr/eeprom.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+
+#include <util/delay.h>
+#include <stdint.h>
+
+#include "hardware.h"
+#include "mm_switch.h"
+
+ #define DEBUG_TIMEOUT
+#ifdef DEBUG_TIMEOUT
+#define MON(val) setpin(PIN_DRIVE, val)
+#else
+#define MON(xx) ({0;})
+#endif
+
+
+/*
+ * Lookup decoder number.
+ *
+ */
+static uint8_t lookup_decoder(uint8_t mm_byte)
+{
+ switch(mm_byte) {
+ /* 0x00 is invalid */
+ case 0xc0: return 1;
+ case 0x80: return 2;
+ case 0x30: return 3;
+ case 0xf0: return 4;
+ case 0xb0: return 5;
+ case 0x20: return 6;
+ case 0xe0: return 7;
+ case 0xa0: return 8;
+
+ case 0x0c: return 9;
+ case 0xcc: return 10;
+ case 0x8c: return 11;
+ case 0x3c: return 12;
+ case 0xfc: return 13;
+ case 0xbc: return 14;
+ case 0x2c: return 15;
+ case 0xec: return 16;
+ case 0xac: return 17;
+
+ case 0x08: return 18;
+ case 0xc8: return 19;
+ case 0x88: return 20;
+ case 0x38: return 21;
+ case 0xf8: return 22;
+ case 0xb8: return 23;
+ case 0x28: return 24;
+ case 0xe8: return 25;
+
+ default:
+ return 0;
+ }
+}
+
+static uint8_t lookup_command(uint8_t mm_byte)
+{
+ switch(mm_byte) {
+ case 0xc3: return 1;
+ case 0x03: return 2;
+ case 0xf3: return 3;
+ case 0x33: return 4;
+ case 0xcf: return 5;
+ case 0x0f: return 6;
+ case 0xff: return 7;
+ case 0x3f: return 8;
+ default:
+ return 0;
+ }
+}
+
+static void mm_switch_init(void)
+{
+ /* Get rid of the 1/8 clock prescaler */
+ CLKPR = (1 << CLKPCE);
+ CLKPR = 0;
+
+ GIMSK |= _BV(PCIE); /* Enable pin change interrupt */
+ PCMSK = _BV(PCINT4); /* PB4, Rail sense input */
+
+ TCCR0A = 0; /* This is normal mode */
+ TCCR0B = 0; /* Timer off */
+ TIMSK |= _BV(OCIE0A); /* Get a match interrupt */
+ TIMSK |= _BV(TOV0); /* Overflow interrupt */
+
+ /* We need 13 + 45 us delay, That's 464 clocks @8MHz*/
+ OCR0A = 91; /* Prescaler 8 is used */
+
+ /* Timer 1 for timeout */
+ /* We set it to 1024us by prescaler 64 and running full 256 */
+ TCCR1 = 7;
+ TIMSK |= _BV(TOIE1); /* Overflow interrupt */
+}
+
+
+static volatile uint8_t shift_sub;
+static volatile uint8_t shift_zero;
+static volatile uint8_t shift_decoder;
+static volatile uint8_t shift_sub_first;
+static volatile uint8_t shift_decoder_first;
+
+/* We will shift from right to left.
+ * XXXXXXXX XX XXXXXXXX
+ * shift_decoder shift_zero shift_sub
+ *
+ * The bits 7 downto 2 of shift_zero are ignored.
+ */
+
+volatile uint8_t bitno = 0;
+
+static void trigger(void)
+{
+ setpin(PIN_DRIVE, 1);
+ _delay_us(10);
+ setpin(PIN_DRIVE, 0);
+}
+
+enum recstate {
+ IDLE = 0,
+ FIRST_FAST_SAMPLE,
+ FIRST_SLOW_SAMPLE, /* If clock arrives, we stay on the fast path! */
+ FAST_SAMPLE,
+ FAST_WAIT_FOR_CLOCK,
+ SLOW_SAMPLE,
+ SLOW_WAIT_FOR_CLOCK,
+};
+
+static enum recstate recstate = IDLE;
+
+static inline void shift(uint8_t value)
+{
+ shift_decoder <<= 1;
+ if (shift_zero & 2)
+ shift_decoder |= 1;
+ shift_zero <<= 1;
+ if (shift_sub & 0x80)
+ shift_zero |= 1;
+ shift_sub <<= 1;
+ if (value)
+ shift_sub |= 1;
+}
+
+
+ISR(TIMER0_COMPA_vect) {
+
+ static uint8_t patience = 0;
+
+ switch(recstate) {
+ case FIRST_FAST_SAMPLE:
+ recstate = FIRST_SLOW_SAMPLE;
+ TSTART_CLK_TO_SAMPLE_FAST; /* Will not run out in fast! */
+ break;
+
+ case FIRST_SLOW_SAMPLE:
+ bitno = 0;
+
+ case SLOW_SAMPLE:
+ recstate = SLOW_WAIT_FOR_CLOCK;
+ TSTART_CLK_TO_SAMPLE_SLOW;
+ break;
+
+ case FAST_SAMPLE:
+ recstate = FAST_WAIT_FOR_CLOCK;
+ TSTART_CLK_TO_SAMPLE_FAST;
+ break;
+
+ case FAST_WAIT_FOR_CLOCK: /* A timeout! */
+ if (patience) {
+ patience--;
+ TSTART_CLK_TO_SAMPLE_FAST;
+ return;
+ }
+ recstate = IDLE;
+ TSTOP;
+ return;
+
+ case SLOW_WAIT_FOR_CLOCK:
+ if (patience) {
+ patience--;
+ TSTART_CLK_TO_SAMPLE_SLOW;
+ return;
+ }
+ TSTOP;
+ recstate = IDLE;
+ return;
+ }
+
+ shift(MM_SENSE);
+ bitno++;
+
+ if (bitno == 18) { /* Save first received word */
+ shift_sub_first = shift_sub;
+ shift_decoder_first = shift_decoder;
+ patience = 18;
+
+ }
+ if (bitno == 36) {
+ if ((shift_sub == shift_sub_first) &&
+ (shift_decoder == shift_decoder_first)) {
+ uint8_t decoder = lookup_decoder(shift_decoder);
+ uint8_t command = lookup_command(shift_sub);
+ if (recstate == SLOW_WAIT_FOR_CLOCK)
+ trigger();
+ if (decoder) {
+ /* Congratulations, we have a valid command */
+ if (recstate == FAST_WAIT_FOR_CLOCK) {
+ // trigger();
+ mm_switch_command(decoder, command);
+ }
+ }
+ }
+ }
+}
+
+ISR(BADISR_vect)
+{
+ while(1) {
+ /*
+ setpin(PIN_LED, 1);
+ _delay_ms(30);
+ setpin(PIN_LED, 0);
+ _delay_ms(30);
+ setpin(PIN_LED, 1);
+ _delay_ms(30);
+ setpin(PIN_LED, 0);
+ _delay_ms(2000);
+ */
+ }
+}
+
+ISR(TIM0_OVF_vect)
+{
+ return;
+ while(1) {
+ setpin(PIN_LED, 1);
+ _delay_ms(30);
+ setpin(PIN_LED, 0);
+ _delay_ms(300);
+ }
+
+}
+
+
+/* Pin change interrupt vector */
+void mm_pinchange_handler(void)
+{
+ static uint8_t sense_last;
+
+ if (MM_SENSE == sense_last)
+ return;
+ sense_last = MM_SENSE;
+ if (!sense_last)
+ return;
+
+ switch(recstate) {
+ case IDLE:
+ bitno = 0;
+ recstate = FIRST_FAST_SAMPLE;
+ TSTART_CLK_TO_SAMPLE_FAST;
+ break;
+ case FIRST_SLOW_SAMPLE:
+ recstate = FAST_SAMPLE;
+ TSTART_CLK_TO_SAMPLE_FAST;
+ break;
+ case FAST_WAIT_FOR_CLOCK:
+ recstate = FAST_SAMPLE;
+ TSTART_CLK_TO_SAMPLE_FAST;
+ break;
+ case SLOW_WAIT_FOR_CLOCK:
+ recstate = SLOW_SAMPLE;
+ TSTART_CLK_TO_SAMPLE_SLOW;
+ break;
+
+ /* Not expected */
+ case FIRST_FAST_SAMPLE:
+ case FAST_SAMPLE:
+ case SLOW_SAMPLE:
+ default:
+ break;
+ }
+}
+
+/******************************************************************************
+ * The end :-)
+ */
+
+
+
projects / eisenbahn.git / blobdiff