# HG changeset patch
# User Malte Bayer <mbayer@neo-soft.org>
# Date 1322054548 -3600
# Node ID 7d4c0c816465b20ab67e99c0e706907b1beb563c
# Parent  d115c088b508a65da8181bcc3f87d528e9640a5e
done working car id measurement via short-blocking function call (slot1-4 for now)

diff -r d115c088b508 -r 7d4c0c816465 receiver/main.c
--- a/receiver/main.c	Wed Nov 23 08:16:38 2011 +0100
+++ b/receiver/main.c	Wed Nov 23 14:22:28 2011 +0100
@@ -12,149 +12,58 @@
 #include "util/delay.h"
 
 
-static char buffer[RS232_BUFSIZE+1];
-static uint8_t buffer_len;
-
-
-
-
-// USART0 RX interrupt
 ISR ( USART_RXC_vect ) {
-    char c = UDR;
+}
 
-    // check for buffer overflow
-    if (buffer_len==sizeof(buffer)) {
-        buffer_len=0;
-        if (c == 27) {
-            // escape sequence, store to empty buffer
-            buffer[buffer_len++] = c;
-        }
-    }  else {
-        // collect characters until end of line
-        if (c == 27) {
-            // escape sequence, clear buffer
-            buffer_len = 0;
-            buffer[buffer_len++] = c;
-        } else if ( (c==0xff) && (buffer_len > 3) ) {
-            buffer[buffer_len]=0;
-
-            // packet end received, parse the received packet
-
-            // wait for the next packet
-            buffer_len=0;
-        } else {
-            buffer[buffer_len++]=c;
-        }
-    }
-}
+// PD2 / PD3 = INT0 / INT1
+// connect IR receiver to these pins to measure frequencies
 
 
-#define PULSE_PORT      PORTD
-#define PULSE_BIT       PD2
-
-volatile uint16_t data = 0;
-volatile uint8_t data_len = 0;
-volatile uint8_t bitbuf_len = 0;
-volatile uint16_t bitbuf = 0;
-
-ISR ( INT0_vect ) {
-    writeBit(PORTD, 5, 1);
-    GICR &= ~_BV(INT0) ; // Disable INT0
-    // Startsignal erkannt, ab hier den Timer2 starten,
-    // der liest dann alle 50µs den Zustand ein und schreibt das
-    // empfangene Bit in den Puffer
-    bitbuf = 0; // init
-    bitbuf_len = 0b10000000; // init 1 pulse received
-    TCNT2 = 0;
-    TIMSK |= _BV(OCIE2); //enable timer2 interrupt
-    writeBit(PORTD, 5, 0);
-}
-
-
-ISR ( TIMER2_COMP_vect ) {
-    writeBit(PORTD, 4, 0);
-
-    uint8_t clock;
-    uint8_t state;
-    uint8_t state2;
-    if ((bitbuf_len & 0b10000000) == 0) clock = 0; else clock = 0xff;
-    if ((bitbuf_len & 0b01000000) == 0) state = 0; else state = 0xff;
-    if ((PIN(PULSE_PORT) & _BV(PULSE_BIT)) == 0) state2 = 0; else state2 = 0xff;
-
-    if (clock) {
-        // second pulse of bit
-        bitbuf_len &= ~_BV(7); // switch clock to low
-        if ((state==state2) & state2) {
-            // two cycles high: packet end received
-            data_len = (bitbuf_len & 0b00111111);
-            if (data_len == 13) PORTD ^= _BV(6); // debug sync output on program packets
-            TIMSK &= ~_BV(OCIE2); //disable timer2 interrupt
-            GICR |= _BV(INT0) ; // Enable INT0
-            data = bitbuf; // output data
-        } else {
-            bitbuf_len++; // increment bit counter
-            bitbuf = bitbuf << 1; // shift bits
-            if (state2 == 0) bitbuf |= 1; // receive logic one
-        }
-    } else {
-        // first pulse of bit
-        bitbuf_len |= _BV(7); // switch clock to high
-        if (state2) {
-            bitbuf_len |= _BV(6); // store new state
-        } else {
-            bitbuf_len &= ~_BV(6); // store new state
+uint8_t get_car(uint8_t pin) {
+    uint8_t i=0xff;
+    // wait ~~ Xµs for low signal
+    while ( (PIN(PORTD) & pin) != 0) {
+        _delay_us(5);
+        i--;
+        if (i==0) return 0; // no low signal, do not longer block
+    }
+    // wait until signal is high again to start measurement
+    while ( (PIN(PORTD) & pin) == 0) ;
+    i = 0;
+    while (i<100) {
+        _delay_us(4);
+        i++;
+        if ( (PIN(PORTD) & pin) == 0) { // return car ID
+            if ( (i>= 5) & (i<= 9) ) return 1; // 05-09 = car1
+            if ( (i>=13) & (i<=16) ) return 2; // 13-16 = car2
+            if ( (i>=19) & (i<=22) ) return 3; // 19-22 = car3
+            if ( (i>=28) & (i<=31) ) return 4; // 28-31 = car4
+            // debug: return higher values:
+            if (i>32) return i;
         }
     }
-
-
-    writeBit(PORTD, 4, 1);
+    return 0; // timeout or incorrect measurement
 }
 
 
-
 int main(void)
 {
-    uint8_t i;
+    uint16_t i;
     unsigned char s[30];
 
-    // setup data bit timer
-    TCCR2 = (1<<CS21) | (1<<WGM21); //divide by 8, set compare match
-    OCR2 = TIMER2_50US;
-    TIMSK |= 1<<OCIE2; //enable timer2 interrupt
-
-    MCUCR = _BV(ISC00); // falling edge
-    GICR = _BV(INT0) ; // Enable INT0
+    RS232_init(); // initialize RS232 interface
+    RS232_puts_p(PSTR("Car ID Scanner v0.1\n"));
 
-    writeBit(DDRD, 4, 1);
-    writeBit(DDRD, 5, 1);
-    writeBit(DDRD, 6, 1);
-
-
-    RS232_init(); // initialize RS232 interface
-    RS232_puts_p(PSTR("CarreraShark 1.0 - INIT OK\n"));
-    //RS232_puts_p(PSTR("Receiving one complete cycle:\n"));
-
-    sei();
-    i = 0;
     while (1) {
         // main loop
 
-        if (data != 0) {
-            if (data_len > 5) {
-                if (data_len == 13) { // sync to first packet
-                    i = 1;
-                    RS232_puts("\n");
-                } else if (i!=0) i++;
-                if (i>0) {
-                    itoa( data, s, 16);
-                    data = 0;
-                    RS232_puts("0x");
-                    RS232_puts( s );
-                    RS232_putc(' ');
-                }
-            }
-            //if (i==10) for (;;);
+        i = get_car(_BV(PD2));
+        if (i > 0) {
+            itoa ( i , s, 10);
+            RS232_puts(s);
+            RS232_putc('\n');
         }
+
     } // main loop end
 };