metakom.c

/*
 * metakom.c
 *
 * Created: 30.01.2016 2:13:32
 *  Author: Elektron
 */ 
#include <avr/io.h>
#include <util/delay.h>
#include "metakom.h"

#define MK_PORT PORTC
#define MK_DDR  DDRC
#define MK_LINE 0

#define ADC0 0b00000000
#define ADC1 0b00000001
#define ADC2 0b00000010
#define ADC3 0b00000011
#define ADC4 0b00000100
#define ADC5 0b00000101
#define ADC6 0b00000110
#define ADC7 0b00000111
#define ADC8 0b00001000

#define AVG_U_SUM 100
#define AVG_T_SUM 100

uint8_t mk_code[9];

void mk_init()
{
    ADCSRA = (1 << ADEN) 								// ðàçðåøåíèå ÀÖÏ
    |(1 << ADSC) 										// çàïóñê ïðåîáðàçîâàíèÿ
    |(1 << ADATE) 										// íåïðåðûâíûé ðåæèì ðàáîòû ÀÖÏ
    |(0 << ADPS2)|(1 << ADPS1)|(1 << ADPS0) 			// ïðåääåëèòåëü íà 8 (÷àñòîòà ÀÖÏ 148kHz)
    |(0 << ADIE); 										// çàïðåò ïðåðûâàíèÿ
    ADCSRB = (0 << ADTS2)|(0 << ADTS1)|(0 << ADTS0); 	// íåïðåðûâíûé ðåæèì ðàáîòû ÀÖÏ

    ADMUX = (0 << REFS1)|(1 << REFS0) 					// îïîðíîå íàïðÿæåíèå AVCC
    |(1 << ADLAR)										// ñìåùåíèå ðåçóëüòàòà (âëåâî ïðè 1, ÷èòàåì 8 áèò èç ADCH)
    |(ADC0); 											// âõîä ADC0
}

uint8_t mk_crc(uint8_t* data)
{
	for(uint8_t i=0;i<4;i++) data[i] = 0;				//î÷èùàåì ìàññèâ êîäà êëþ÷à
	
	if((mk_code[0] & 0xE0) != 0b01000000) return MK_NO_KEY;	//ïðîâåðÿåì íàëè÷èå ñòàðòîâîãî ñëîâà
	
	for(uint8_t i=0;i<8;i++)								//ïðîâåðÿåì ñîâïàäåíèå äâóõ êîïèé êîäà êëþ÷à
		if(((mk_code[i/8]<<(i%8)) & 0x80) != ((mk_code[(i+35)/8]<<((i+35)%8)) & 0x80)) return MK_NO_KEY;
															
	for(uint8_t i=0;i<32;i++)								//êîïèðóåì êîä êëþ÷à â ìàññèâ
		if(mk_code[(i+3)/8] & 0x80>>((i+3)%8)) data[i/8] |= 0x80>>(i%8);
	
	for(uint8_t i=0;i<4;i++){								//ïðîâåðÿåì ÷åòíîñòü
		uint8_t parity = 0;
		for(uint8_t j=0;j<7;j++){
			if(data[i] & 0x80>>j) parity ^= 0x01; 
		}
		if((data[i] & 0x01) != parity) return MK_NO_KEY;
	}
	return MK_READ_OK;
}

uint8_t mk_read(uint8_t* data)
{
	uint16_t sum = 0;
	uint8_t avg_t = 0, avg_u = 0, temp = 0;
	
	for(uint8_t i=0;i<9;i++)mk_code[i] = 0;					//÷èñòèì ìàññèâ ïðèåìà

	for(uint8_t i=0;i<AVG_U_SUM;i++){						//îïðåäåëÿåì ñðåäíåå íàïðÿæåíèå
		sum += ADCH;
		_delay_us(10);
	}
	avg_u = sum / AVG_U_SUM;
	sum = 0;
	for(uint8_t u=0,i=0;i<AVG_T_SUM;i++){					//îïðåäåëÿåì äëèòåëüíîñòü öèêëà ãåíåðàòîðà êëþ÷à
		for(uint8_t t=0;t<200;t++){
			if(ADCH < avg_u && u){sum += t; u = 0;break;}
			if(ADCH > avg_u && !u){sum += t; u = 1;break;}
			_delay_us(4);
		}
	}
	avg_t = sum / AVG_T_SUM;
	if(avg_t < 5 || avg_t > 23) return MK_NO_KEY;

	for(uint8_t i=0;i<255;i++){								//æäåì ñèíõðîíèçèðóþùèé áèò
		uint8_t t;
		_delay_us(10);
		if(ADCH >= avg_u) continue;
		for (t=0;t<100;t++){
			_delay_us(10);
			if(ADCH > avg_u) break;
		}
		if(t > avg_t) {temp = 1;break;}
	}
	if(temp == 0) return MK_NO_KEY;
	
	for(uint8_t i=0;i<70;i++){							//ïèøåì â áóôåð ïðèåìà ñòàðòîâîå ñëîâî è êîä êëþ÷à äâàæäû
		uint8_t t;
		for (t=0;t<=150;t++){
			if(ADCH < avg_u) break;
			_delay_us(4);
		}
		if(t == 150) return MK_NO_KEY;
		
		if(t > avg_t) mk_code[i/8] |= 0x80>>(i%8);
		
		for (t=0;t<=150;t++){
			if(ADCH > avg_u) break;
			_delay_us(4);
		}
		if(t == 150) return MK_NO_KEY;		
	}
	
	return mk_crc(data);
}