DS1820 Dallas 1-Wire Temperature Probe. More...

#include <DS1820.h>

Public Member Functions
	DS1820 (PinName data_pin, PinName power_pin)
	Create a probe object connected to the specified pins.
	DS1820 (PinName data_pin)
	Create a probe object connected to the specified pin this is used when all probes are externally powered.
void	search_Rom_setup ()
	This routine initializes the global variables used in the search_Rom() and search_alarm() funtions.
bool	search_Rom ()
	This routine will search for an unidentified device on the bus.
bool	search_alarm ()
	This routine will search for an unidentified device which has the temperature alarm bit set.
void	read_Rom ()
	This routine will read the RomMMMM (Family code, serial number and Checksum) fRomM a dedicated device on the bus.
void	convert_temperature (devices device=this_device)
	This routine will initiate the temperature conversion within a DS1820.
float	temperature (char scale='c')
	This function will return the probe temperature.
bool	Rom_checksum_error ()
	This function calculates the Rom checksum and compares it to the CRC value stored in RomMMM[7].
bool	RAM_checksum_error ()
	This function calculates the RAM checksum and compares it to the CRC value stored in RAM[8].
bool	set_configuration_bits (unsigned int resolution)
	This function returns the values stored in the temperature alarm registers.
int	read_scratchpad ()
	This function sets the temperature resolution for the DS18B20 in the configuration register.
void	write_scratchpad (int data)
	This function will store the passed data into the DS1820's RAM.
void	store_scratchpad (devices device=this_device)
	This function will transfer the TH and TL registers fRomM the DS1820's RAM into the EEPRomMMMM.
int	recall_scratchpad (devices device=this_device)
	This function will copy the stored values fRomMMM the EEPRomM into the DS1820's RAM locations for TH and TL.
bool	read_power_supply (devices device=this_device)
	This function will return the type of power supply for a specific device.
Data Fields
char	Rom [8]
	RomMMM is a copy of the internal DS1820's Rom It is created during the search_RomM() or search_alarm() commands.
char	RAM [9]
	RAM is a copy of the internal DS1820's RAM It's updated during the read_RAM() command which is automaticaly called fRom any function using the RAM values.

Detailed Description

DS1820 Dallas 1-Wire Temperature Probe.

Example:

 #include "mbed.h"

 #include "TextLCD.h"
 #include "DS1820.h"

 TextLCD lcd(p25, p26, p21, p22, p23, p24, TextLCD::LCD16x2); // rs, e, d0-d3, layout

 const int MAX_PROBES = 16;
 DS1820* probe[MAX_PROBES];

 int main() {
     int i;
     int devices_found=0;
     // Initialize the probe array to DS1820 objects
     for (i = 0; i < MAX_PROBES; i++)
         probe[i] = new DS1820(p27);
     // Initialize global state variables
     probe[0]->search_RomMM_setup();
     // Loop to find all devices on the data line
     while (probe[devices_found]->search_RomM() and devices_found<MAX_PROBES-1)
         devices_found++;
     // If maximum number of probes are found,
     // bump the counter to include the last array entry
     if (probe[devices_found]->RomMMMM[0] != 0xFF)
         devices_found++;

     lcd.cls();
     if (devices_found==0)
         lcd.printf("No devices found");
     else {
         while (true) {
             probe[0]->convert_temperature(DS1820::all_devices);
             lcd.cls();
             for (i=0; i<devices_found; i++) {
                 lcd.printf("%3.1f ",probe[i]->temperature('f'));
             }
         }
     }
 }

Definition at line 81 of file DS1820.h.

Constructor & Destructor Documentation

DS1820	(	PinName	data_pin,
		PinName	power_pin
	)

Create a probe object connected to the specified pins.

Parameters:

data_pin	DigitalInOut pin for the data bus
power_pin	DigitalOut pin to control the power MOSFET

Definition at line 10 of file DS1820.cpp.

DS1820 ( PinName data_pin )

Create a probe object connected to the specified pin this is used when all probes are externally powered.

Parameters:

data_pin DigitalInOut pin for the data bus

Definition at line 18 of file DS1820.cpp.

Member Function Documentation

void convert_temperature ( devices device = this_device )

This routine will initiate the temperature conversion within a DS1820.

There is a built in 750ms delay to allow the conversion to complete.

To update all probes on the bus, use a statement such as this: probe[0]->convert_temperature(DS1820::all_devices);

Parameters:

allows the fnction to apply to a specific device or to all devices on the 1-Wire bus.

Definition at line 249 of file DS1820.cpp.

bool RAM_checksum_error ( )

This function calculates the RAM checksum and compares it to the CRC value stored in RAM[8].

Returns:: true if the checksum matches, otherwise false.

Definition at line 207 of file DS1820.cpp.

bool read_power_supply ( devices device = this_device )

This function will return the type of power supply for a specific device.

It can also be used to query all devices looking for any device that is parasite powered.

Returns:: true if the device (or all devices) are Vcc powered, returns false if the device (or ANY device) is parasite powered.

Definition at line 381 of file DS1820.cpp.

void read_Rom ( )

This routine will read the RomMMMM (Family code, serial number and Checksum) fRomM a dedicated device on the bus.

NOTE: This command can only be used when there is only one DS1820 on the bus. If this command is used when there is more than one slave present on the bus, a data collision will occur when all the DS1820s attempt to respond at the same time.

Definition at line 173 of file DS1820.cpp.

int read_scratchpad ( )

This function sets the temperature resolution for the DS18B20 in the configuration register.

Parameters:

a	number between 9 and 12 to specify the resolution

Returns:: true if successful

Definition at line 300 of file DS1820.cpp.

int recall_scratchpad ( devices device = this_device )

This function will copy the stored values fRomMMM the EEPRomM into the DS1820's RAM locations for TH and TL.

Parameters:

allows the function to apply to a specific device or to all devices on the 1-Wire bus.

Definition at line 332 of file DS1820.cpp.

bool Rom_checksum_error ( )

This function calculates the Rom checksum and compares it to the CRC value stored in RomMMM[7].

Returns:: true if the checksum matches, otherwise false.

Definition at line 198 of file DS1820.cpp.

bool search_alarm ( )

This routine will search for an unidentified device which has the temperature alarm bit set.

It uses the variables in search_RomMMM_setup to remember the pervious RomMMM address found. It will return FALSE if there were no new devices with alarms discovered on the bus.

Definition at line 89 of file DS1820.cpp.

bool search_Rom ( )

This routine will search for an unidentified device on the bus.

It uses the variables in search_RomMMMM_setup to remember the pervious RomMMMM address found. It will return FALSE if there were no new devices discovered on the bus.

Definition at line 85 of file DS1820.cpp.

void search_Rom_setup ( )

This routine initializes the global variables used in the search_Rom() and search_alarm() funtions.

It should be called once before looping to find devices.

Definition at line 162 of file DS1820.cpp.

bool set_configuration_bits ( unsigned int resolution )

This function returns the values stored in the temperature alarm registers.

Returns:: a 16 bit integer of TH (upper byte) and TL (lower byte).

Definition at line 287 of file DS1820.cpp.

void store_scratchpad ( devices device = this_device )

This function will transfer the TH and TL registers fRomM the DS1820's RAM into the EEPRomMMMM.

Note: There is a built in 10ms delay to allow for the completion of the EEPRomMMM write cycle.

Parameters:

allows the fnction to apply to a specific device or to all devices on the 1-Wire bus.

Definition at line 319 of file DS1820.cpp.

float temperature ( char scale = 'c' )

This function will return the probe temperature.

This function uses the count remainding values to interpolate the temperature to about 1/150th of a degree. Whereas the probe is not spec to that precision. It does seem to give a smooth reading to the tenth of a degree.

Parameters:

scale,may be either 'c' or 'f'

Returns:: temperature for that scale

Definition at line 351 of file DS1820.cpp.

void write_scratchpad ( int data )

This function will store the passed data into the DS1820's RAM.

Note: It does NOT save the data to the EEPRomMMM for retention during cycling the power off and on.

Parameters:

a	16 bit integer of TH (upper byte) and TL (lower byte).

Definition at line 307 of file DS1820.cpp.

Field Documentation

char RAM[9]

RAM is a copy of the internal DS1820's RAM It's updated during the read_RAM() command which is automaticaly called fRom any function using the RAM values.

Definition at line 121 of file DS1820.h.

char Rom[8]

RomMMM is a copy of the internal DS1820's Rom It is created during the search_RomM() or search_alarm() commands.

RomMMM[0] is the Dallas Family Code RomMMM[1] thru RomMMM[6] is the 48-bit unique serial number RomMMM[7] is the device CRC

Definition at line 110 of file DS1820.h.

Type:	Library
Created:	17 Jun 2016
Imports:	2
Forks:	0
Commits:	4
Dependents:	2
Dependencies:	0
Followers:	6

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Field Documentation

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Member Function Documentation

Field Documentation

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