Alexander Scheinost / DS18B20

Libary for DS18B20 working in MBED-OS

ds18b20.cpp@0:1abc4873af36, 2020-11-04 (annotated)

Committer:
Scheinost_Alexander
Date:
Wed Nov 04 07:36:02 2020 +0000
Revision:
0:1abc4873af36
Libary for DS18B20; working in MBED-OS

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Scheinost_Alexander 0:1abc4873af36 1 #include "ds18b20.h"
Scheinost_Alexander 0:1abc4873af36 2
Scheinost_Alexander 0:1abc4873af36 3 OWI::OWI(PinName pin):owi_io(pin)
Scheinost_Alexander 0:1abc4873af36 4 {
Scheinost_Alexander 0:1abc4873af36 5
Scheinost_Alexander 0:1abc4873af36 6 }
Scheinost_Alexander 0:1abc4873af36 7
Scheinost_Alexander 0:1abc4873af36 8 void OWI::write0()
Scheinost_Alexander 0:1abc4873af36 9 {
Scheinost_Alexander 0:1abc4873af36 10 owi_io.output(); // timeslot = 70us
Scheinost_Alexander 0:1abc4873af36 11 owi_io.write(0); // owi = 0;
Scheinost_Alexander 0:1abc4873af36 12 wait_us(60);
Scheinost_Alexander 0:1abc4873af36 13 owi_io.input();
Scheinost_Alexander 0:1abc4873af36 14 wait_us(10);
Scheinost_Alexander 0:1abc4873af36 15 }
Scheinost_Alexander 0:1abc4873af36 16
Scheinost_Alexander 0:1abc4873af36 17 void OWI::write1() // timeslot = 70us
Scheinost_Alexander 0:1abc4873af36 18 {
Scheinost_Alexander 0:1abc4873af36 19 owi_io.output();
Scheinost_Alexander 0:1abc4873af36 20 owi_io.write(0); // owi = 0;
Scheinost_Alexander 0:1abc4873af36 21 wait_us(6);
Scheinost_Alexander 0:1abc4873af36 22 owi_io.input();
Scheinost_Alexander 0:1abc4873af36 23 wait_us(64);
Scheinost_Alexander 0:1abc4873af36 24 }
Scheinost_Alexander 0:1abc4873af36 25
Scheinost_Alexander 0:1abc4873af36 26 unsigned char OWI::readBit()
Scheinost_Alexander 0:1abc4873af36 27 {
Scheinost_Alexander 0:1abc4873af36 28 unsigned char readbit;
Scheinost_Alexander 0:1abc4873af36 29
Scheinost_Alexander 0:1abc4873af36 30 owi_io.output();
Scheinost_Alexander 0:1abc4873af36 31 owi_io.write(0); // owi = 0;
Scheinost_Alexander 0:1abc4873af36 32 wait_us(6);
Scheinost_Alexander 0:1abc4873af36 33 owi_io.input();
Scheinost_Alexander 0:1abc4873af36 34 wait_us(9);
Scheinost_Alexander 0:1abc4873af36 35 readbit = owi_io.read();
Scheinost_Alexander 0:1abc4873af36 36 wait_us(55);
Scheinost_Alexander 0:1abc4873af36 37
Scheinost_Alexander 0:1abc4873af36 38 return readbit;
Scheinost_Alexander 0:1abc4873af36 39 }
Scheinost_Alexander 0:1abc4873af36 40
Scheinost_Alexander 0:1abc4873af36 41 unsigned char OWI::detectPresence()
Scheinost_Alexander 0:1abc4873af36 42 {
Scheinost_Alexander 0:1abc4873af36 43 core_util_critical_section_enter();
Scheinost_Alexander 0:1abc4873af36 44
Scheinost_Alexander 0:1abc4873af36 45 unsigned char presencebit;
Scheinost_Alexander 0:1abc4873af36 46
Scheinost_Alexander 0:1abc4873af36 47 owi_io.output();
Scheinost_Alexander 0:1abc4873af36 48 owi_io.write(0); // owi = 0;
Scheinost_Alexander 0:1abc4873af36 49 wait_us(480);
Scheinost_Alexander 0:1abc4873af36 50 owi_io.input();
Scheinost_Alexander 0:1abc4873af36 51 wait_us(70);
Scheinost_Alexander 0:1abc4873af36 52 presencebit = !owi_io.read();
Scheinost_Alexander 0:1abc4873af36 53 wait_us(410);
Scheinost_Alexander 0:1abc4873af36 54
Scheinost_Alexander 0:1abc4873af36 55 core_util_critical_section_exit();
Scheinost_Alexander 0:1abc4873af36 56
Scheinost_Alexander 0:1abc4873af36 57 return presencebit;
Scheinost_Alexander 0:1abc4873af36 58 }
Scheinost_Alexander 0:1abc4873af36 59
Scheinost_Alexander 0:1abc4873af36 60 void OWI::sendByte(unsigned char data)
Scheinost_Alexander 0:1abc4873af36 61 {
Scheinost_Alexander 0:1abc4873af36 62 core_util_critical_section_enter();
Scheinost_Alexander 0:1abc4873af36 63
Scheinost_Alexander 0:1abc4873af36 64 unsigned char temp;
Scheinost_Alexander 0:1abc4873af36 65 unsigned char i;
Scheinost_Alexander 0:1abc4873af36 66 for (i = 0; i < 8; i++)
Scheinost_Alexander 0:1abc4873af36 67 {
Scheinost_Alexander 0:1abc4873af36 68 temp = data & 0x01;
Scheinost_Alexander 0:1abc4873af36 69 if (temp)
Scheinost_Alexander 0:1abc4873af36 70 {
Scheinost_Alexander 0:1abc4873af36 71 this->write1();
Scheinost_Alexander 0:1abc4873af36 72 }
Scheinost_Alexander 0:1abc4873af36 73 else
Scheinost_Alexander 0:1abc4873af36 74 {
Scheinost_Alexander 0:1abc4873af36 75 this->write0();
Scheinost_Alexander 0:1abc4873af36 76 }
Scheinost_Alexander 0:1abc4873af36 77 data >>= 1;
Scheinost_Alexander 0:1abc4873af36 78 }
Scheinost_Alexander 0:1abc4873af36 79
Scheinost_Alexander 0:1abc4873af36 80 core_util_critical_section_exit();
Scheinost_Alexander 0:1abc4873af36 81 }
Scheinost_Alexander 0:1abc4873af36 82
Scheinost_Alexander 0:1abc4873af36 83 unsigned char OWI::receiveByte()
Scheinost_Alexander 0:1abc4873af36 84 {
Scheinost_Alexander 0:1abc4873af36 85 core_util_critical_section_enter();
Scheinost_Alexander 0:1abc4873af36 86
Scheinost_Alexander 0:1abc4873af36 87 unsigned char data;
Scheinost_Alexander 0:1abc4873af36 88 unsigned char i;
Scheinost_Alexander 0:1abc4873af36 89 data = 0x00;
Scheinost_Alexander 0:1abc4873af36 90 for (i = 0; i < 8; i++)
Scheinost_Alexander 0:1abc4873af36 91 {
Scheinost_Alexander 0:1abc4873af36 92 data >>= 1;
Scheinost_Alexander 0:1abc4873af36 93 if (this->readBit())
Scheinost_Alexander 0:1abc4873af36 94 {
Scheinost_Alexander 0:1abc4873af36 95 data |= 0x80;
Scheinost_Alexander 0:1abc4873af36 96 }
Scheinost_Alexander 0:1abc4873af36 97 }
Scheinost_Alexander 0:1abc4873af36 98
Scheinost_Alexander 0:1abc4873af36 99 core_util_critical_section_exit();
Scheinost_Alexander 0:1abc4873af36 100 return data;
Scheinost_Alexander 0:1abc4873af36 101 }
Scheinost_Alexander 0:1abc4873af36 102
Scheinost_Alexander 0:1abc4873af36 103
Scheinost_Alexander 0:1abc4873af36 104 DS18B20::DS18B20(PinName pin):DS18B20_OWI(pin)
Scheinost_Alexander 0:1abc4873af36 105 {
Scheinost_Alexander 0:1abc4873af36 106
Scheinost_Alexander 0:1abc4873af36 107 }
Scheinost_Alexander 0:1abc4873af36 108
Scheinost_Alexander 0:1abc4873af36 109 float DS18B20::readTemp()
Scheinost_Alexander 0:1abc4873af36 110 {
Scheinost_Alexander 0:1abc4873af36 111 unsigned char msb,lsb;
Scheinost_Alexander 0:1abc4873af36 112 int itemp;
Scheinost_Alexander 0:1abc4873af36 113 float ftemp;
Scheinost_Alexander 0:1abc4873af36 114
Scheinost_Alexander 0:1abc4873af36 115 DS18B20_OWI.detectPresence();
Scheinost_Alexander 0:1abc4873af36 116 DS18B20_OWI.sendByte(OWI_SKIP_ROM);
Scheinost_Alexander 0:1abc4873af36 117 DS18B20_OWI.sendByte(DS18S20_START);
Scheinost_Alexander 0:1abc4873af36 118
Scheinost_Alexander 0:1abc4873af36 119 ThisThread::sleep_for(750);
Scheinost_Alexander 0:1abc4873af36 120
Scheinost_Alexander 0:1abc4873af36 121 DS18B20_OWI.detectPresence();
Scheinost_Alexander 0:1abc4873af36 122 DS18B20_OWI.sendByte(OWI_SKIP_ROM);
Scheinost_Alexander 0:1abc4873af36 123 DS18B20_OWI.sendByte(DS18S20_READ_SCRATCH_PAD);
Scheinost_Alexander 0:1abc4873af36 124 lsb = DS18B20_OWI.receiveByte();
Scheinost_Alexander 0:1abc4873af36 125 msb = DS18B20_OWI.receiveByte();
Scheinost_Alexander 0:1abc4873af36 126
Scheinost_Alexander 0:1abc4873af36 127 itemp = (msb<<8)+lsb;
Scheinost_Alexander 0:1abc4873af36 128 ftemp = (float)itemp / 16.0f;
Scheinost_Alexander 0:1abc4873af36 129
Scheinost_Alexander 0:1abc4873af36 130 return ftemp;
Scheinost_Alexander 0:1abc4873af36 131 }