Revision 0:61d83318f2d6, committed 2010-12-19

Comitter:

Michael_

Date:

Sun Dec 19 05:40:28 2010 +0000

Child:

1:6a427f54e82c

Commit message:

Dec 18, 2010 First pubication

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DS1820.cpp	Sun Dec 19 05:40:28 2010 +0000
@@ -0,0 +1,357 @@
+#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
+    if (device==all_devices)
+        skip_ROM();          // Skip ROM command, will convert for ALL devices
+    else
+        match_ROM();
+    onewire_byte_out( 0x44);  // perform temperature conversion
+    if (_parasite_power)
+        _parasitepin = 1;       // Parasite power strong pullup
+    wait_ms(750);
+    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();
+    }
+}
+
+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)
+}
+
+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
+    }
+    remaining_count = RAM[6];
+    count_per_degree = RAM[7];
+    answer = reading +0.0;
+    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();
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DS1820.h	Sun Dec 19 05:40:28 2010 +0000
@@ -0,0 +1,252 @@
+/* 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];
+    
+    /** 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 funtion returns the values stored in the temperature
+      * alarm registers. 
+      *
+      * @returns a 16 bit integer of TH (upper byte) and TL (lower byte).
+      */
+    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 fnction 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