Michael Hagberg
Dallas / Maxim DS1820 1-Wire library. For communication with multiple DS1820 on a single 1-Wire bus. Also supports DS18S20 and DS18B20.
Revision 2:ee820a991b95, committed 2011-12-15
- Comitter:
- Michael_
- Date:
- Thu Dec 15 19:07:36 2011 +0000
- Parent:
- 1:6a427f54e82c
- Commit message:
- Updated documentation. (maybe)
Changed in this revision
| DS1820.cpp | Show annotated file Show diff for this revision Revisions of this file |
| DS1820.h | Show annotated file Show diff for this revision Revisions of this file |
--- a/DS1820.cpp Wed Dec 14 20:22:16 2011 +0000
+++ b/DS1820.cpp Thu Dec 15 19:07:36 2011 +0000
@@ -1,390 +0,0 @@
-#include "DS1820.h"
-#include "mbed.h"
-
-// Global variables shared between all DS1820 objects
-bool DS1820_done_flag;
-int DS1820_last_descrepancy;
-char DS1820_search_ROM[8];
-
-
-DS1820::DS1820 (PinName data_pin, PinName power_pin) : _datapin(data_pin), _parasitepin(power_pin) {
- int byte_counter;
- _parasite_power = true;
- for(byte_counter=0;byte_counter<8;byte_counter++)
- ROM[byte_counter] = 0xFF;
- for(byte_counter=0;byte_counter<9;byte_counter++)
- RAM[byte_counter] = 0x00;
-}
-DS1820::DS1820 (PinName data_pin) : _datapin(data_pin), _parasitepin(NC) {
- int byte_counter;
- _parasite_power = false;
- for(byte_counter=0;byte_counter<8;byte_counter++)
- ROM[byte_counter] = 0xFF;
- for(byte_counter=0;byte_counter<9;byte_counter++)
- RAM[byte_counter] = 0x00;
-}
-
-bool DS1820::onewire_reset() {
-// This will return false if no devices are present on the data bus
- bool presence=false;
- _datapin.output();
- _datapin = 0; // bring low for 500 us
- wait_us(500);
- _datapin.input(); // let the data line float high
- wait_us(90); // wait 90us
- if (_datapin.read()==0) // see if any devices are pulling the data line low
- presence=true;
- wait_us(410);
- return presence;
-}
-
-void DS1820::onewire_bit_out (bool bit_data) {
- _datapin.output();
- _datapin = 0;
- wait_us(5);
- if (bit_data) {
- _datapin.input(); // bring data line high
- wait_us(55);
- } else {
- wait_us(55); // keep data line low
- _datapin.input();
- }
-}
-
-void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
- int n;
- for (n=0; n<8; n++) {
- onewire_bit_out(data & 0x01);
- data = data >> 1; // now the next bit is in the least sig bit position.
- }
-}
-
-bool DS1820::onewire_bit_in() {
- bool answer;
- _datapin.output();
- _datapin = 0;
- wait_us(5);
- _datapin.input();
- wait_us(5);
- answer = _datapin.read();
- wait_us(50);
- return answer;
-}
-
-char DS1820::onewire_byte_in() { // read byte, least sig byte first
- char answer = 0x00;
- int i;
- for (i=0; i<8; i++) {
- answer = answer >> 1; // shift over to make room for the next bit
- if (onewire_bit_in())
- answer = answer | 0x80; // if the data port is high, make this bit a 1
- }
- return answer;
-}
-
-bool DS1820::search_ROM() {
- return search_ROM_routine(0xF0); // Search ROM command
-}
-
-bool DS1820::search_alarm() {
- return search_ROM_routine(0xEC); // Search Alarm command
-}
-
-bool DS1820::search_ROM_routine(char command) {
- extern bool DS1820_done_flag;
- extern int DS1820_last_descrepancy;
- extern char DS1820_search_ROM[8];
- int descrepancy_marker, ROM_bit_index;
- bool return_value, Bit_A, Bit_B;
- char byte_counter, bit_mask;
-
- return_value=false;
- if (!DS1820_done_flag) {
- if (!onewire_reset()) {
- DS1820_last_descrepancy = 0; // no devices present
- } else {
- ROM_bit_index=1;
- descrepancy_marker=0;
- onewire_byte_out(command); // Search ROM command or Search Alarm command
- byte_counter = 0;
- bit_mask = 0x01;
- while (ROM_bit_index<=64) {
- Bit_A = onewire_bit_in();
- Bit_B = onewire_bit_in();
- if (Bit_A & Bit_B) {
- descrepancy_marker = 0; // data read error, this should never happen
- ROM_bit_index = 0xFF;
- } else {
- if (Bit_A | Bit_B) {
- // Set ROM bit to Bit_A
- if (Bit_A) {
- DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
- } else {
- DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
- }
- } else {
- // both bits A and B are low, so there are two or more devices present
- if ( ROM_bit_index == DS1820_last_descrepancy ) {
- DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
- } else {
- if ( ROM_bit_index > DS1820_last_descrepancy ) {
- DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
- descrepancy_marker = ROM_bit_index;
- } else {
- if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
- descrepancy_marker = ROM_bit_index;
- }
- }
- }
- onewire_bit_out (DS1820_search_ROM[byte_counter] & bit_mask);
- ROM_bit_index++;
- if (bit_mask & 0x80) {
- byte_counter++;
- bit_mask = 0x01;
- } else {
- bit_mask = bit_mask << 1;
- }
- }
- }
- DS1820_last_descrepancy = descrepancy_marker;
- if (ROM_bit_index != 0xFF) {
- for(byte_counter=0;byte_counter<8;byte_counter++)
- ROM[byte_counter] = DS1820_search_ROM[byte_counter];
- return_value = true;
- }
- }
- if (DS1820_last_descrepancy == 0)
- DS1820_done_flag = true;
- }
- return return_value;
-}
-
-void DS1820::search_ROM_setup() {
- extern bool DS1820_done_flag;
- extern int DS1820_last_descrepancy;
- extern char DS1820_search_ROM[8];
- DS1820_done_flag = false;
- DS1820_last_descrepancy = 0;
- int i;
- for (i=0; i<8; i++)
- DS1820_search_ROM[i]=0x00;
-}
-
-void DS1820::read_ROM() {
- // NOTE: This command can only be used when there is 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.
- int i;
- onewire_reset();
- onewire_byte_out(0x33); // Read ROM id
- for (i=0; i<8; i++)
- ROM[i]=onewire_byte_in();
-}
-
-void DS1820::match_ROM() {
-// Used to select a specific device
- int i;
- onewire_reset();
- onewire_byte_out( 0x55); //Match ROM command
- for (i=0;i<8;i++)
- onewire_byte_out(ROM[i]);
-}
-
-void DS1820::skip_ROM() {
- onewire_reset();
- onewire_byte_out(0xCC); // Skip ROM command
-}
-
-bool DS1820::ROM_checksum_error() {
- char CRC=0x00;
- int i;
- for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
- CRC = CRC_byte(CRC, ROM[i]);
- // After 7 bytes CRC should equal the 8th byte (ROM CRC)
- return (CRC!=ROM[7]); // will return true if there is a CRC checksum error
-}
-
-bool DS1820::RAM_checksum_error() {
- char CRC=0x00;
- int i;
- read_RAM();
- for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
- CRC = CRC_byte(CRC, RAM[i]);
- // After 8 bytes CRC should equal the 9th byte (RAM CRC)
- return (CRC!=RAM[8]); // will return true if there is a CRC checksum error
-}
-
-char DS1820::CRC_byte (char CRC, char byte ) {
- int j;
- for(j=0;j<8;j++) {
- if ((byte & 0x01 ) ^ (CRC & 0x01)) {
- // DATA ^ LSB CRC = 1
- CRC = CRC>>1;
- // Set the MSB to 1
- CRC = CRC | 0x80;
- // Check bit 3
- if (CRC & 0x04) {
- CRC = CRC & 0xFB; // Bit 3 is set, so clear it
- } else {
- CRC = CRC | 0x04; // Bit 3 is clear, so set it
- }
- // Check bit 4
- if (CRC & 0x08) {
- CRC = CRC & 0xF7; // Bit 4 is set, so clear it
- } else {
- CRC = CRC | 0x08; // Bit 4 is clear, so set it
- }
- } else {
- // DATA ^ LSB CRC = 0
- CRC = CRC>>1;
- // clear MSB
- CRC = CRC & 0x7F;
- // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
- }
- byte = byte>>1;
- }
-return CRC;
-}
-
-void DS1820::convert_temperature(devices device) {
- // Convert temperature into scratchpad RAM for all devices at once
- int delay_time = 750; // Default delay time
- char resolution;
- if (device==all_devices)
- skip_ROM(); // Skip ROM command, will convert for ALL devices
- else {
- match_ROM();
- if (FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
- resolution = RAM[4] & 0x60;
- if (resolution == 0x00) // 9 bits
- delay_time = 94;
- if (resolution == 0x20) // 10 bits
- delay_time = 188;
- if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
- delay_time = 375;
- }
- }
- onewire_byte_out( 0x44); // perform temperature conversion
- if (_parasite_power)
- _parasitepin = 1; // Parasite power strong pullup
- wait_ms(delay_time);
- if (_parasite_power)
- _parasitepin = 0;
-}
-
-void DS1820::read_RAM() {
- // This will copy the DS1820's 9 bytes of RAM data
- // into the objects RAM array. Functions that use
- // RAM values will automaticly call this procedure.
- int i;
- match_ROM(); // Select this device
- onewire_byte_out( 0xBE); //Read Scratchpad command
- for(i=0;i<9;i++) {
- RAM[i] = onewire_byte_in();
- }
-}
-
-bool DS1820::set_configuration_bits(unsigned int resolution) {
- bool answer = false;
- resolution = resolution - 9;
- if (resolution < 4) {
- resolution = resolution<<5; // align the bits
- RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
- write_scratchpad ((RAM[2]<<8) + RAM[3]);
-// store_scratchpad (DS1820::this_device); // Need to test if this is required
- answer = true;
- }
- return answer;
-}
-
-int DS1820::read_scratchpad() {
- int answer;
- read_RAM();
- answer = (RAM[2]<<8) + RAM[3];
- return answer;
-}
-
-void DS1820::write_scratchpad(int data) {
- RAM[3] = data;
- RAM[2] = data>>8;
- match_ROM();
- onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
- onewire_byte_out(RAM[2]); // T(H)
- onewire_byte_out(RAM[3]); // T(L)
- if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
- onewire_byte_out(RAM[4]); // Configuration register
- }
-}
-
-void DS1820::store_scratchpad(devices device) {
- if (device==all_devices)
- skip_ROM(); // Skip ROM command, will store for ALL devices
- else
- match_ROM();
- onewire_byte_out(0x48); // Write scratchpad into E2 command
- if (_parasite_power)
- _parasitepin=1;
- wait_ms(10); // Parasite power strong pullup for 10ms
- if (_parasite_power)
- _parasitepin=0;
-}
-
-int DS1820::recall_scratchpad(devices device) {
-// This copies the E2 values into the DS1820's memory.
-// If you specify all_devices this will return zero, otherwise
-// it will return the value of the scratchpad memory.
- int answer=0;
- if (device==all_devices)
- skip_ROM(); // Skip ROM command, will recall for ALL devices
- else
- match_ROM();
- onewire_byte_out(0xB8); // Recall E2 data to scratchpad command
- wait_ms(10); // not sure I like polling for completion
- // it could cause an infinite loop
- if (device==DS1820::this_device) {
- read_RAM();
- answer = read_scratchpad();
- }
- return answer;
-}
-
-float DS1820::temperature(char scale) {
-// The data specs state that count_per_degree should be 0x10 (16), I found my devices
-// to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
-// this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
-// being super acurate, but it does allow for a smooth display in the 1/10ths of a
-// deg C or F scales.
- float answer, remaining_count, count_per_degree;
- int reading;
- read_RAM();
- reading = (RAM[1] << 8) + RAM[0];
- if (reading & 0x8000) { // negative degrees C
- reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
- }
- answer = reading +0.0; // convert to floating point
- if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
- answer = answer / 8.0;
- }
- else {
- remaining_count = RAM[6];
- count_per_degree = RAM[7];
- answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
- }
- if (scale=='C' or scale=='c')
- answer = answer / 2.0;
- else
- // Convert to deg F
- answer = answer * 9.0 / 10.0 + 32.0;
- return answer;
-}
-
-bool DS1820::read_power_supply(devices device) {
-// This will return true if the device (or all devices) are Vcc powered
-// This will return false if the device (or ANY device) is parasite powered
- if (device==all_devices)
- skip_ROM(); // Skip ROM command, will poll for any device using parasite power
- else
- match_ROM();
- onewire_byte_out(0xB4); // Read power supply command
- return onewire_bit_in();
-}
--- a/DS1820.h Wed Dec 14 20:22:16 2011 +0000
+++ b/DS1820.h Thu Dec 15 19:07:36 2011 +0000
@@ -1,264 +1,264 @@
-/* mbed DS1820 Library, for the Dallas (Maxim) 1-Wire Digital Thermometer
- * Copyright (c) 2010, Michael Hagberg Michael@RedBoxCode.com
- *
- * 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.
- */
-
-#ifndef MBED_DS1820_H
-#define MBED_DS1820_H
-
-#include "mbed.h"
-
-// ****** THIS GLOBAL VARIABLES MUST BE DEFINED IN main.cpp
-
-// Global variables shared between all DS1820 objects
-//bool DS1820_done_flag;
-//int DS1820_last_descrepancy;
-//char DS1820_search_ROM[8];
-
-/** DS1820 Dallas 1-Wire Temperature Probe
- *
- * Example:
- * @code
- * #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_ROM_setup();
- * // Loop to find all devices on the data line
- * while (probe[devices_found]->search_ROM() 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]->ROM[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'));
- * }
- * }
- * }
- * }
- * @endcode
- */
-
-class DS1820 {
-public:
- enum devices{
- this_device, // command applies to only this device
- all_devices }; // command applies to all devices
-
- /** Create a probe object connected to the specified pins
- *
- * @param data_pin DigitalInOut pin for the data bus
- * @param power_pin DigitalOut pin to control the power MOSFET
- */
- DS1820(PinName data_pin, PinName power_pin); // Constructor with parasite power pin
-
- /** Create a probe object connected to the specified pin
- * this is used when all probes are externally powered
- *
- * @param data_pin DigitalInOut pin for the data bus
- */
- DS1820(PinName data_pin);
-
- /** ROM is a copy of the internal DS1820's ROM
- * It's created during the search_ROM() or search_alarm() commands
- *
- * ROM[0] is the Dallas Family Code
- * ROM[1] thru ROM[6] is the 48-bit unique serial number
- * ROM[7] is the device CRC
- */
- char ROM[8];
- #define FAMILY_CODE ROM[0]
- #define FAMILY_CODE_DS1820 0x10
- #define FAMILY_CODE_DS18S20 0x10
- #define FAMILY_CODE_DS18B20 0x28
-
- /** 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.
- */
- char RAM[9];
-
- /* This function copies the DS1820's RAM into the object's
- * RAM[].
- */
- void read_RAM();
-
- /** 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.
- */
- void search_ROM_setup();
-
- /** This routine will search for an unidentified device
- * on the bus. It uses the variables in search_ROM_setup
- * to remember the pervious ROM address found.
- * It will return FALSE if there were no new devices
- * discovered on the bus.
- */
- bool search_ROM();
-
- /** This routine will search for an unidentified device
- * which has the temperature alarm bit set. It uses the
- * variables in search_ROM_setup to remember the pervious
- * ROM address found. It will return FALSE if there were
- * no new devices with alarms discovered on the bus.
- */
- bool search_alarm();
-
- /** This routine will read the ROM (Family code, serial number
- * and Checksum) from 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.
- */
- void read_ROM();
-
- /** 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);
- *
- * @param allows the fnction to apply to a specific device or
- * to all devices on the 1-Wire bus.
- */
- void convert_temperature(devices device=this_device);
-
- /** 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.
- *
- * @param scale, may be either 'c' or 'f'
- * @returns temperature for that scale
- */
- float temperature(char scale='c');
-
- /** This function calculates the ROM checksum and compares it to the
- * CRC value stored in ROM[7].
- *
- * @returns true if the checksum matches, otherwise false.
- */
- bool ROM_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.
- */
- bool RAM_checksum_error();
-
- /** This function returns the values stored in the temperature
- * alarm registers.
- *
- * @returns a 16 bit integer of TH (upper byte) and TL (lower byte).
- */
- bool set_configuration_bits(unsigned int resolution);
-
- /** This function sets the temperature resolution for the DS18B20
- * in the configuration register.
- *
- * @param a number between 9 and 12 to specify the resolution
- * @returns true if successful
- */
- int read_scratchpad();
-
- /** This function will store the passed data into the DS1820's RAM.
- * Note: It does NOT save the data to the EEPROM for retention
- * during cycling the power off and on.
- *
- * @param a 16 bit integer of TH (upper byte) and TL (lower byte).
- */
- void write_scratchpad(int data);
-
- /** This function will transfer the TH and TL registers from the
- * DS1820's RAM into the EEPROM.
- * Note: There is a built in 10ms delay to allow for the
- * completion of the EEPROM write cycle.
- *
- * @param allows the fnction to apply to a specific device or
- * to all devices on the 1-Wire bus.
- */
- void store_scratchpad(devices device=this_device);
-
- /** This function will copy the stored values from the EEPROM
- * into the DS1820's RAM locations for TH and TL.
- *
- * @param allows the function to apply to a specific device or
- * to all devices on the 1-Wire bus.
- */
- int recall_scratchpad(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.
- */
- bool read_power_supply(devices device=this_device);
-
-private:
- bool _parasite_power;
- char CRC_byte (char CRC, char byte );
- bool onewire_reset();
- void match_ROM();
- void skip_ROM();
- bool search_ROM_routine(char command);
- void onewire_bit_out (bool bit_data);
- void onewire_byte_out(char data);
- bool onewire_bit_in();
- char onewire_byte_in();
-
-protected:
- DigitalInOut _datapin;
- DigitalOut _parasitepin;
-};
-
-
-#endif
+/* mbed DS1820 Library, for the Dallas (Maxim) 1-Wire Digital Thermometer
+ * Copyright (c) 2010, Michael Hagberg Michael@RedBoxCode.com
+ *
+ * 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.
+ */
+
+#ifndef MBED_DS1820_H
+#define MBED_DS1820_H
+
+#include "mbed.h"
+
+// ****** THIS GLOBAL VARIABLES MUST BE DEFINED IN main.cpp
+
+// Global variables shared between all DS1820 objects
+//bool DS1820_done_flag;
+//int DS1820_last_descrepancy;
+//char DS1820_search_ROM[8];
+
+/** DS1820 Dallas 1-Wire Temperature Probe
+ *
+ * Example:
+ * @code
+ * #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_ROM_setup();
+ * // Loop to find all devices on the data line
+ * while (probe[devices_found]->search_ROM() 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]->ROM[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'));
+ * }
+ * }
+ * }
+ * }
+ * @endcode
+ */
+
+class DS1820 {
+public:
+ enum devices{
+ this_device, // command applies to only this device
+ all_devices }; // command applies to all devices
+
+ /** Create a probe object connected to the specified pins
+ *
+ * @param data_pin DigitalInOut pin for the data bus
+ * @param power_pin DigitalOut pin to control the power MOSFET
+ */
+ DS1820(PinName data_pin, PinName power_pin); // Constructor with parasite power pin
+
+ /** Create a probe object connected to the specified pin
+ * this is used when all probes are externally powered
+ *
+ * @param data_pin DigitalInOut pin for the data bus
+ */
+ DS1820(PinName data_pin);
+
+ /** ROM is a copy of the internal DS1820's ROM
+ * It is created during the search_ROM() or search_alarm() commands
+ *
+ * ROM[0] is the Dallas Family Code
+ * ROM[1] thru ROM[6] is the 48-bit unique serial number
+ * ROM[7] is the device CRC
+ */
+ char ROM[8];
+ #define FAMILY_CODE ROM[0]
+ #define FAMILY_CODE_DS1820 0x10
+ #define FAMILY_CODE_DS18S20 0x10
+ #define FAMILY_CODE_DS18B20 0x28
+
+ /** 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.
+ */
+ char RAM[9];
+
+ /* This function copies the DS1820's RAM into the object's
+ * RAM[].
+ */
+ void read_RAM();
+
+ /** 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.
+ */
+ void search_ROM_setup();
+
+ /** This routine will search for an unidentified device
+ * on the bus. It uses the variables in search_ROM_setup
+ * to remember the pervious ROM address found.
+ * It will return FALSE if there were no new devices
+ * discovered on the bus.
+ */
+ bool search_ROM();
+
+ /** This routine will search for an unidentified device
+ * which has the temperature alarm bit set. It uses the
+ * variables in search_ROM_setup to remember the pervious
+ * ROM address found. It will return FALSE if there were
+ * no new devices with alarms discovered on the bus.
+ */
+ bool search_alarm();
+
+ /** This routine will read the ROM (Family code, serial number
+ * and Checksum) from 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.
+ */
+ void read_ROM();
+
+ /** 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);
+ *
+ * @param allows the fnction to apply to a specific device or
+ * to all devices on the 1-Wire bus.
+ */
+ void convert_temperature(devices device=this_device);
+
+ /** 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.
+ *
+ * @param scale, may be either 'c' or 'f'
+ * @returns temperature for that scale
+ */
+ float temperature(char scale='c');
+
+ /** This function calculates the ROM checksum and compares it to the
+ * CRC value stored in ROM[7].
+ *
+ * @returns true if the checksum matches, otherwise false.
+ */
+ bool ROM_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.
+ */
+ bool RAM_checksum_error();
+
+ /** This function returns the values stored in the temperature
+ * alarm registers.
+ *
+ * @returns a 16 bit integer of TH (upper byte) and TL (lower byte).
+ */
+ bool set_configuration_bits(unsigned int resolution);
+
+ /** This function sets the temperature resolution for the DS18B20
+ * in the configuration register.
+ *
+ * @param a number between 9 and 12 to specify the resolution
+ * @returns true if successful
+ */
+ int read_scratchpad();
+
+ /** This function will store the passed data into the DS1820's RAM.
+ * Note: It does NOT save the data to the EEPROM for retention
+ * during cycling the power off and on.
+ *
+ * @param a 16 bit integer of TH (upper byte) and TL (lower byte).
+ */
+ void write_scratchpad(int data);
+
+ /** This function will transfer the TH and TL registers from the
+ * DS1820's RAM into the EEPROM.
+ * Note: There is a built in 10ms delay to allow for the
+ * completion of the EEPROM write cycle.
+ *
+ * @param allows the fnction to apply to a specific device or
+ * to all devices on the 1-Wire bus.
+ */
+ void store_scratchpad(devices device=this_device);
+
+ /** This function will copy the stored values from the EEPROM
+ * into the DS1820's RAM locations for TH and TL.
+ *
+ * @param allows the function to apply to a specific device or
+ * to all devices on the 1-Wire bus.
+ */
+ int recall_scratchpad(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.
+ */
+ bool read_power_supply(devices device=this_device);
+
+private:
+ bool _parasite_power;
+ char CRC_byte (char CRC, char byte );
+ bool onewire_reset();
+ void match_ROM();
+ void skip_ROM();
+ bool search_ROM_routine(char command);
+ void onewire_bit_out (bool bit_data);
+ void onewire_byte_out(char data);
+ bool onewire_bit_in();
+ char onewire_byte_in();
+
+protected:
+ DigitalInOut _datapin;
+ DigitalOut _parasitepin;
+};
+
+
+#endif
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