Umair Aftab / Mbed 2 deprecated Autus Featured

Project Autus - Automated Plant Chamber

Dependencies:   TextLCD mbed

Fork of keypad_test by Plamen Totev

Autus

This is the codebase accompanying the project Autus.

Autus is an automated growth chamber for plants.

Features

Control Humidity inside chamber wrt to external humidity. Control Temperature inside chamber. ( Peltier Heaters/Coolers ) Water and shower plants. Control soil humidity. Monitor water tanks level (Load Cell) /media/uploads/umairaftab/frdm_-_new_page1.png

Code Base Features

Fixed timing and CRC for DHT-11 Sensor. Fixed OneWire bug for ds18b20

Cyclic Executive Scheduler with Priority. Async IPC framework for PC App over bluetooth

Fake RTC systick, I was having some trouble with the on board rtc.

/media/uploads/umairaftab/download.png

SEN11301P/DHT.cpp

Committer:
umairaftab
Date:
2014-04-09
Revision:
4:8d1df60ef3c3

File content as of revision 4:8d1df60ef3c3:


#include "DHT.h"

#define DHT_DATA_BIT_COUNT 40

DHT::DHT(PinName pin,int DHTtype) {
    _pin = pin;
    _DHTtype = DHTtype;
    _firsttime=true;
}

DHT::~DHT() {
}

int DHT::readData() {
    int i, j, retryCount,b;
    unsigned int bitTimes[DHT_DATA_BIT_COUNT];

    eError err = ERROR_NONE;
    time_t currentTime = time(NULL);

    DigitalInOut DHT_io(_pin);

    for (i = 0; i < DHT_DATA_BIT_COUNT; i++) {
        bitTimes[i] = 0;
    }

    if (!_firsttime) {
        if (int(currentTime - _lastReadTime) < 2) {
            err = ERROR_NO_PATIENCE;
            return err;
        }
    } else {
        _firsttime=false;
        _lastReadTime=currentTime;
    }
    retryCount = 0;

    do {
        if (retryCount > 125) {
            err = BUS_BUSY;
            return err;
        }
        retryCount ++;
        wait_us(2);
    } while ((DHT_io==0));


    DHT_io.output();
    DHT_io = 0;
    wait_ms(18);
    DHT_io = 1;
    wait_us(40);
    DHT_io.input();

    retryCount = 0;
    do {
        if (retryCount > 40)  {
            err = ERROR_NOT_PRESENT;
            return err;
        }
        retryCount++;
        wait_us(1);
    } while ((DHT_io==1));

    if (err != ERROR_NONE) {
        return err;
    }

    wait_us(80);

    for (i = 0; i < 5; i++) {
        for (j = 0; j < 8; j++) {

            retryCount = 0;
            do {
                if (retryCount > 75)  {
                    err = ERROR_DATA_TIMEOUT;
                    return err;
                }
                retryCount++;
                wait_us(1);
            } while (DHT_io == 0);
            wait_us(40);
            bitTimes[i*8+j]=DHT_io;

            int count = 0;
            while (DHT_io == 1 && count < 100) {
                wait_us(1);
                count++;
            }
        }
    }
    DHT_io.output();
    DHT_io = 1;
    for (i = 0; i < 5; i++) {
        b=0;
        for (j=0; j<8; j++) {
            if (bitTimes[i*8+j+1] > 0) {
                b |= ( 1 << (7-j));
            }
        }
        DHT_data[i]=b;
    }

    if (DHT_data[4] == ((DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3]) & 0xFF)) {
        _lastReadTime = currentTime;
        _lastTemperature=CalcTemperature();
        _lastHumidity=CalcHumidity();

    } else {
        err = ERROR_CHECKSUM;
    }

    return err;

}

float DHT::CalcTemperature() {
    int v;

    switch (_DHTtype) {
        case DHT11:
            v = DHT_data[2];
            return float(v);
        case DHT22:
            v = DHT_data[2] & 0x7F;
            v *= 256;
            v += DHT_data[3];
            v /= 10;
            if (DHT_data[2] & 0x80)
                v *= -1;
            return float(v);
    }
    return 0;
}

float DHT::ReadHumidity() {
    return _lastHumidity;
}

float DHT::ConvertCelciustoFarenheit(float celsius) {
    return celsius * 9 / 5 + 32;
}

float DHT::ConvertCelciustoKelvin(float celsius) {
    return celsius + 273.15;
}

// dewPoint function NOAA
// reference: http://wahiduddin.net/calc/density_algorithms.htm
float DHT::CalcdewPoint(float celsius, float humidity) {
    float A0= 373.15/(273.15 + celsius);
    float SUM = -7.90298 * (A0-1);
    SUM += 5.02808 * log10(A0);
    SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
    SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
    SUM += log10(1013.246);
    float VP = pow(10, SUM-3) * humidity;
    float T = log(VP/0.61078);   // temp var
    return (241.88 * T) / (17.558-T);
}

// delta max = 0.6544 wrt dewPoint()
// 5x faster than dewPoint()
// reference: http://en.wikipedia.org/wiki/Dew_point
float DHT::CalcdewPointFast(float celsius, float humidity)
{
        float a = 17.271;
        float b = 237.7;
        float temp = (a * celsius) / (b + celsius) + log(humidity/100);
        float Td = (b * temp) / (a - temp);
        return Td;
}

float DHT::ReadTemperature(eScale Scale) {
    if (Scale == FARENHEIT)
        return ConvertCelciustoFarenheit(_lastTemperature);
    else if (Scale == KELVIN)
        return ConvertCelciustoKelvin(_lastTemperature);
    else
        return _lastTemperature;
}

float DHT::CalcHumidity() {
    int v;

    switch (_DHTtype) {
        case DHT11:
            v = DHT_data[0];
            return float(v);
        case DHT22:
            v = DHT_data[0];
            v *= 256;
            v += DHT_data[1];
            v /= 10;
            return float(v);
    }
    return 0;
}