/*
* Q-Touch-Test mit Tiny25 (auch 85)
* Sensor an SNSK
* 120R - 33nF zwischen SNSK uns SNS
*/

#include <stdio.h>
#include <avr/io.h>
#include <util/delay.h>
#include <util/atomic.h>

#include "sbit.h"
//#include "uart.h"

// multiple definitions for H/L
#define EIN 		1
#define ON			1
#define AUS 		0
#define OFF			0
#define LOW			0
#define HIGH		1

#define OUTPUT 		1
#define INPUT 		0

// Ports
#define SNSK		PORT_B3	
#define SNSK_DIR	DDR_B3
#define SNSK_PIN	PIN_B3

#define SNS			PORT_B4  
#define SNS_DIR		DDR_B4
#define SNS_PIN		PIN_B4

#define LEDP		PORT_B1
#define LEDP_DIR	DDR_B1

// Konstanten
#define MAXCNT 1000
#define DELTA 50


int16_t get_sensor_cnt(void)
{
	int16_t cnt = MAXCNT; 
	SNS_DIR = SNSK_DIR = INPUT;
	SNSK = 1; // Pullup
	SNSK_DIR = OUTPUT; // strong HIGH, lade Cx

// Loop
	ATOMIC_BLOCK(ATOMIC_FORCEON)
	{
		do
		{
			SNSK_DIR = INPUT;  // weak HIGH
			SNSK = 0; 		// Pull off: HiZ

			// 2. charge Transfer
			SNS_DIR = OUTPUT; 	// LOW, da SNS immer 0
	
			// Read SNSK
			SNS_DIR = INPUT;
			SNSK = 1; // weak HIGH
			SNSK_DIR = OUTPUT; // strong HIGH: Lade Cx (Kapazität des Sensors)
			if (--cnt == 0) break;  
		} while (SNS_PIN == 1);
	}
	SNS_DIR  = OUTPUT;
	SNS = SNSK = 0;
		
	return cnt; 
}

int main ()
{
	int16_t sens_cnt, i=1, sens_old; 
	uint8_t flag_pressed=0;

	LEDP_DIR = OUTPUT; 
	LEDP = OFF;
	SNS_DIR = SNSK_DIR = OUTPUT;
	SNS = SNSK = 0;

	get_sensor_cnt();  // dummy
	_delay_ms(5);
	sens_old = get_sensor_cnt();
	_delay_ms(5);

	while (1)
	{
		sens_cnt = get_sensor_cnt();  // neue Abtastung
		
		_delay_ms(20); i++;
		if (i%100 == 0 && flag_pressed==0) sens_old = (3*sens_old + sens_cnt+2)/4;
		else if (sens_cnt < sens_old) sens_old--;
		if (sens_old < 0) sens_old=0;  // sollte nicht notwendig sein, aber: int
		if (sens_cnt-sens_old > DELTA && !flag_pressed) {flag_pressed=1; LEDP ^=1;}
		if (sens_cnt-sens_old < (DELTA+1) &&  flag_pressed) {flag_pressed=0;}
	}
}