File content as of revision 1:27d0c6ee0e55:

/*	MIT License
*
*	Copyright (c) 2020 Lukas Gessner
*
*	Permission is hereby granted, free of charge, to any person obtaining a copy
*	of this software and associated documentation files (the "Software"), to deal
*	in the Software without restriction, including without limitation the rights
*	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
*	copies of the Software, and to permit persons to whom the Software is
*	furnished to do so, subject to the following conditions:
*
*	The above copyright notice and this permission notice shall be included in all
*	copies or substantial portions of the Software.
*
*	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
*	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
*	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
*	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
*	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
*	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*	SOFTWARE.
*/

#include "DS18B20.h"

OWI::OWI(PinName pin):owi_io(pin)
{
	
}

void OWI::write0()
{
     owi_io.output();  // timeslot = 70us
     owi_io.write(0);  // owi = 0;
     wait_us(60);
     owi_io.input();
     wait_us(10);       
}

void OWI::write1()    // timeslot = 70us
{
     owi_io.output();
     owi_io.write(0);  // owi = 0;
     wait_us(6);
     owi_io.input();
     wait_us(64);   
}

unsigned char OWI::readBit()
{
     unsigned char readbit;
     
     owi_io.output();
     owi_io.write(0);  // owi = 0;
     wait_us(6);
     owi_io.input();
     wait_us(9);
     readbit = owi_io.read();
     wait_us(55);
     
     return readbit;
}

unsigned char OWI::detectPresence()
{
     core_util_critical_section_enter();
	 
	 unsigned char presencebit;
     
     owi_io.output();
     owi_io.write(0);  // owi = 0;
     wait_us(480);
     owi_io.input();
     wait_us(70);
     presencebit = !owi_io.read();
     wait_us(410);
	 
	 core_util_critical_section_exit();
     
     return presencebit;
}

void OWI::sendByte(unsigned char data)
{
     core_util_critical_section_enter();
	 
	 unsigned char temp;
     unsigned char i;
     for (i = 0; i < 8; i++)
     {
         temp = data & 0x01;
         if (temp)
         {
              this->write1();
         }
         else
         {
              this->write0();
         } 
         data >>= 1;
     }
	 
	 core_util_critical_section_exit();
}

unsigned char OWI::receiveByte()
{
     core_util_critical_section_enter();
	 
	 unsigned char data;
     unsigned char i;
     data = 0x00;
     for (i = 0; i < 8; i++)
     {
         data >>= 1;
         if (this->readBit())
         {
               data |= 0x80;
         }
     }
	 
	 core_util_critical_section_exit();
     return data;
}


DS18B20::DS18B20(PinName pin):DS18B20_OWI(pin)
{

}

float DS18B20::readTemp()
{
    unsigned char msb,lsb;
    int itemp;
    float ftemp;
	
	DS18B20_OWI.detectPresence();
    DS18B20_OWI.sendByte(OWI_SKIP_ROM);
    DS18B20_OWI.sendByte(DS18B20_START);
	
	#if MBED_MAJOR_VERSION >= 6
		ThisThread::sleep_for(750ms);
	#elif MBED_MAJOR_VERSION < 5
		wait(0.75);
	#else
		ThisThread::sleep_for(750);
	#endif
        
    DS18B20_OWI.detectPresence();
    DS18B20_OWI.sendByte(OWI_SKIP_ROM);
    DS18B20_OWI.sendByte(DS18B20_READ_SCRATCH_PAD);
    lsb = DS18B20_OWI.receiveByte();
    msb = DS18B20_OWI.receiveByte();
        
    itemp = (msb<<8)+lsb;
    ftemp = (float)itemp / 16.0f;      
	
	return ftemp;
}