WiFi_433_Transceiver/main/Sensors/nexa.c

#include "nexa.h"
#include <stdint.h>
#include <stdio.h>
#include "../rxTimer.h"
#include "../led.h"

#define FACTOR 9
#define CONV(a) ((((a)*FACTOR) / 100) + (a))

struct nexaData_t {
  unsigned char bitNo;
  unsigned short width;
} ;

enum { UNKNOWN, T0, T1, T2, T3, OK_Sensor, DONE };

static uint8_t rx_state = UNKNOWN;

static uint64_t sensor_data;
static uint32_t rx_numBits;
static uint8_t x_2ndbit;

void NEXA_resetDecoder () {
	sensor_data = 0;
	rx_numBits = 0;
	x_2ndbit = false;
	rx_state = UNKNOWN;
}

static void addBit (uint8_t value) {

	// X
	rx_numBits++;
	sensor_data = (sensor_data << 1) + (value & 0x01);
	if( x_2ndbit == false ) {
		x_2ndbit = true;
	}
	else {
		x_2ndbit = false;
		unsigned int bits = (sensor_data & 0x03);
		if( bits == 2 ) {
			// Bit is 1
			sensor_data = (sensor_data >> 1) | 0x00000001;
		}
		else {
			// Bit is 0
			sensor_data = (sensor_data >> 1) & 0xFFFFFFFE;
		}
	}

	rx_state = OK_Sensor;
}

static int rx_decode(uint32_t width) {
  
    if( rx_numBits == 3 ) {	// end of frame
          //state = DONE;
          //return 1;
	}
        
	switch (rx_state) {
        case UNKNOWN: // Start of frame
            if ( 2240 <= width && width <= 3540 ) {
                rx_state = T0;
            }
            else {
                return -1;	// error, reset
            }
            break;

        case T0: // First half of pulse

            if ( 155 <= width && width <= 305 ) {
                rx_state = T1;
            }
            else {
                if( rx_numBits == 0 && 2240 <= width && width <= 3540 ) {
                    rx_state = T0;
                }
                else {
                    return -1;	// error, reset
                }
            }
            break;

        case T1:
            if ( 240 <= width && width <= 440 ) {
                addBit(0);
            } else if ( (1410-300) <= width && width <= (1410+300) ) {
                //debug_width = width;
                addBit(1);
            } else if( rx_numBits == 64 ) {	// end of frame
                rx_state = DONE;
                return 1;
            } else  {
                return -1;	// error, reset
            }
            rx_state = T0;
            break;
	}
	return 0;
}

#define TOO_SHORT 100

int64_t nextPulseNEXA(uint32_t width)
{
    static int64_t previous_data = 0;
    static uint32_t old_time=0;
    static uint32_t now;
    int64_t retVal = -1;

    if (width > 0)
    {
        if (rx_state != DONE)
        {
            switch (rx_decode(width))
            {
            case -1:
                NEXA_resetDecoder();
                break;
            case 1:
                rx_state = DONE;
                //printf("%d\n",debug_width);
                break;
            }
        }
    }
    if (rx_state == DONE) {
        now = millis();
        if( sensor_data != previous_data || (now > (old_time+1000)) ) {
            previous_data = sensor_data;
            retVal = sensor_data;
            blinkTheLED();
        }
        old_time = now;
        NEXA_resetDecoder();
    }
    
    return retVal;
}