Interface for Dallas DS18B20 digital thermometer device.

Dependents:   WIZ550io_Xively_Demo ESP8266-WEB-Mbed-Controller BrewCtrl Brew_Keg ... more

The output from the example program should look like this.

/media/uploads/richardlane/ds18b20_terminal.png

Committer:
richardlane
Date:
Fri Jul 05 22:14:08 2013 +0000
Revision:
0:769f9b2b30d5
Child:
1:00972ed59ba3
Initial commit.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
richardlane 0:769f9b2b30d5 1 #ifndef DS18B20_H
richardlane 0:769f9b2b30d5 2 #define DS18B20_H
richardlane 0:769f9b2b30d5 3
richardlane 0:769f9b2b30d5 4 #include "mbed.h"
richardlane 0:769f9b2b30d5 5 #include <stdint.h>
richardlane 0:769f9b2b30d5 6
richardlane 0:769f9b2b30d5 7 /** A DS18B20 Dallas 1-wire digital thermometer interface.
richardlane 0:769f9b2b30d5 8 *
richardlane 0:769f9b2b30d5 9 * Currently supports 9, 10, 11 or 12-bit conversions. Fewer bits
richardlane 0:769f9b2b30d5 10 * require less conversion time from 93.75ms to 750ms. Also supports
richardlane 0:769f9b2b30d5 11 * reading back the 8-byte internal ROM. Orignal code copied from
richardlane 0:769f9b2b30d5 12 * DS18B20 C program by Niall Cooling (thanks!) and wrapped in C++
richardlane 0:769f9b2b30d5 13 * class by this library.
richardlane 0:769f9b2b30d5 14 *
richardlane 0:769f9b2b30d5 15 * @code
richardlane 0:769f9b2b30d5 16 * #include "mbed.h"
richardlane 0:769f9b2b30d5 17 * #include <stdint.h>
richardlane 0:769f9b2b30d5 18 * #include "DS18B20.h"
richardlane 0:769f9b2b30d5 19 *
richardlane 0:769f9b2b30d5 20 * Serial pc(USBTX, USBRX); // serial comms over usb back to console
richardlane 0:769f9b2b30d5 21 * DS18B20 thermom(p16, DS18B20::RES_12_BIT); // Dallas 1-wire
richardlane 0:769f9b2b30d5 22 *
richardlane 0:769f9b2b30d5 23 * int main() {
richardlane 0:769f9b2b30d5 24 * pc.printf("DS18B20 Configuration\n\r");
richardlane 0:769f9b2b30d5 25 *
richardlane 0:769f9b2b30d5 26 * DS18B20::ROM_Code_t ROM_Code;
richardlane 0:769f9b2b30d5 27 * thermom.ReadROM(&ROM_Code);
richardlane 0:769f9b2b30d5 28 * pc.printf("Family code: 0x%X\n\r", ROM_Code.BYTES.familyCode);
richardlane 0:769f9b2b30d5 29 * pc.printf("Serial Number: ");
richardlane 0:769f9b2b30d5 30 * for (unsigned i = 6; i != 0; --i) {
richardlane 0:769f9b2b30d5 31 * pc.printf("%02X%s", ROM_Code.BYTES.serialNo[i-1], (i != 1)?":":"\r\n");
richardlane 0:769f9b2b30d5 32 * }
richardlane 0:769f9b2b30d5 33 * pc.printf("CRC: 0x%X\r\n", ROM_Code.BYTES.CRC);
richardlane 0:769f9b2b30d5 34 *
richardlane 0:769f9b2b30d5 35 * pc.printf("\n\rRunning temperature conversion...\n\r");
richardlane 0:769f9b2b30d5 36 * while (1) {
richardlane 0:769f9b2b30d5 37 * pc.printf("Temperature is: %.4fC\n\r", thermom.GetTemperature());
richardlane 0:769f9b2b30d5 38 * wait(10);
richardlane 0:769f9b2b30d5 39 * }
richardlane 0:769f9b2b30d5 40 * }
richardlane 0:769f9b2b30d5 41 * @endcode
richardlane 0:769f9b2b30d5 42 */
richardlane 0:769f9b2b30d5 43
richardlane 0:769f9b2b30d5 44 class DS18B20
richardlane 0:769f9b2b30d5 45 {
richardlane 0:769f9b2b30d5 46 public:
richardlane 0:769f9b2b30d5 47 /** Value to return when Reset() fails */
richardlane 0:769f9b2b30d5 48 enum {INVALID_TEMPERATURE = -10000};
richardlane 0:769f9b2b30d5 49
richardlane 0:769f9b2b30d5 50 /** Temperature conversion dit width resolutions */
richardlane 0:769f9b2b30d5 51 enum RESOLUTION { RES_9_BIT=0x1f, /**< 93.75ms */
richardlane 0:769f9b2b30d5 52 RES_10_BIT=0x3f, /**< 187.5ms */
richardlane 0:769f9b2b30d5 53 RES_11_BIT=0x5f, /**< 375ms */
richardlane 0:769f9b2b30d5 54 RES_12_BIT=0x7f }; /**< 750ms */
richardlane 0:769f9b2b30d5 55
richardlane 0:769f9b2b30d5 56 /** Holds 8-byte internal ROM */
richardlane 0:769f9b2b30d5 57 typedef union {
richardlane 0:769f9b2b30d5 58 uint8_t rom[8];
richardlane 0:769f9b2b30d5 59 struct {
richardlane 0:769f9b2b30d5 60 uint8_t familyCode; /**< Family Code */
richardlane 0:769f9b2b30d5 61 uint8_t serialNo[6]; /**< Serial Number */
richardlane 0:769f9b2b30d5 62 uint8_t CRC; /**< CRC check byte */
richardlane 0:769f9b2b30d5 63 } BYTES;
richardlane 0:769f9b2b30d5 64 } ROM_Code_t;
richardlane 0:769f9b2b30d5 65
richardlane 0:769f9b2b30d5 66 /** Device onboard register layout (for reference only, not currently used) */
richardlane 0:769f9b2b30d5 67 typedef struct {
richardlane 0:769f9b2b30d5 68 uint8_t LSB; /**< LSB of converted temperature */
richardlane 0:769f9b2b30d5 69 uint8_t MSB; /**< MSB of converted temperature */
richardlane 0:769f9b2b30d5 70 uint8_t Th; /**< Threshold for high alarm */
richardlane 0:769f9b2b30d5 71 uint8_t Tl; /**< Threshold for low alarm */
richardlane 0:769f9b2b30d5 72 uint8_t config; /**< Conversion resultion */
richardlane 0:769f9b2b30d5 73 uint8_t reserved0xFF;
richardlane 0:769f9b2b30d5 74 uint8_t reserved0xCH;
richardlane 0:769f9b2b30d5 75 uint8_t reserved0x10;
richardlane 0:769f9b2b30d5 76 uint8_t CRC; /**< CRC check byte */
richardlane 0:769f9b2b30d5 77 } ScratchPad_t;
richardlane 0:769f9b2b30d5 78
richardlane 0:769f9b2b30d5 79 /** Create a Dallas DS18B20 1-wire interface
richardlane 0:769f9b2b30d5 80 *
richardlane 0:769f9b2b30d5 81 * @param pin Pin to use for 1-wire interface (bidirectional I/O)
richardlane 0:769f9b2b30d5 82 * @param resolution Sets the conversion bit width (using RESOLUTION enum)
richardlane 0:769f9b2b30d5 83 */
richardlane 0:769f9b2b30d5 84 DS18B20(PinName pin, unsigned resolution);
richardlane 0:769f9b2b30d5 85
richardlane 0:769f9b2b30d5 86 /** Destructor */
richardlane 0:769f9b2b30d5 87 ~DS18B20();
richardlane 0:769f9b2b30d5 88
richardlane 0:769f9b2b30d5 89 /** Performs conversion in DS18B20 and then reads and converts returned temperature
richardlane 0:769f9b2b30d5 90 * to floating point. For many applications this is the only required method that
richardlane 0:769f9b2b30d5 91 * needs to be used.
richardlane 0:769f9b2b30d5 92 */
richardlane 0:769f9b2b30d5 93 float GetTemperature();
richardlane 0:769f9b2b30d5 94
richardlane 0:769f9b2b30d5 95 /** Performs conversion but does not read back temperature. Not needed if
richardlane 0:769f9b2b30d5 96 * GetTemperature() is used as this calls DoConversion() itself. */
richardlane 0:769f9b2b30d5 97 unsigned DoConversion();
richardlane 0:769f9b2b30d5 98
richardlane 0:769f9b2b30d5 99 /** The method that GetTemperature() calls to do all the conversion and reading
richardlane 0:769f9b2b30d5 100 * but this method returns a 32-bit signed integer. The integer contains 4
richardlane 0:769f9b2b30d5 101 * fractional LSBs. Sometimes referred to as s28.4 format. */
richardlane 0:769f9b2b30d5 102 int RawTemperature();
richardlane 0:769f9b2b30d5 103
richardlane 0:769f9b2b30d5 104 /** Reads and returns the 8-byte internal ROM */
richardlane 0:769f9b2b30d5 105 int ReadROM(ROM_Code_t *ROM_Code);
richardlane 0:769f9b2b30d5 106
richardlane 0:769f9b2b30d5 107 /** Sets the conversion resolution with RESOLUTION enum (9-12 bits signed) */
richardlane 0:769f9b2b30d5 108 unsigned SetResolution(unsigned resolution);
richardlane 0:769f9b2b30d5 109
richardlane 0:769f9b2b30d5 110 protected:
richardlane 0:769f9b2b30d5 111
richardlane 0:769f9b2b30d5 112 // Timing delay for 1-wire serial standard option
richardlane 0:769f9b2b30d5 113 enum DELAY { A = 6, B = 64, C = 60, D = 10, E = 9, F = 55, G = 0, H = 480, I = 70, J = 410 };
richardlane 0:769f9b2b30d5 114
richardlane 0:769f9b2b30d5 115 // Device byte commands over 1-wire serial
richardlane 0:769f9b2b30d5 116 enum COMMANDS { READ_ROM = 0x33, CONVERT = 0x44, READ_SCRATCHPAD = 0xBE, WRITE_SCRATCHPAD = 0x4E, SKIP_ROM = 0xCC };
richardlane 0:769f9b2b30d5 117
richardlane 0:769f9b2b30d5 118 // Methods from DS1Wire.h
richardlane 0:769f9b2b30d5 119 unsigned Reset();
richardlane 0:769f9b2b30d5 120 void WriteBit(unsigned bit);
richardlane 0:769f9b2b30d5 121 unsigned ReadBit();
richardlane 0:769f9b2b30d5 122 void WriteByte(unsigned byte);
richardlane 0:769f9b2b30d5 123 unsigned ReadByte();
richardlane 0:769f9b2b30d5 124
richardlane 0:769f9b2b30d5 125 // The pin used for the Dallas 1-wire interface
richardlane 0:769f9b2b30d5 126 DigitalInOut _pin;
richardlane 0:769f9b2b30d5 127 };
richardlane 0:769f9b2b30d5 128
richardlane 0:769f9b2b30d5 129 #endif