initial commit

DS2438.cpp

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+/*
+ *   DS2438.cpp
+ *
+ *   by Joe Bechter
+ *
+ *   (C) 2012, bechter.com
+ *
+ *   All files, software, schematics and designs are provided as-is with no warranty.
+ *   All files, software, schematics and designs are for experimental/hobby use.
+ *   Under no circumstances should any part be used for critical systems where safety,
+ *   life or property depends upon it. You are responsible for all use.
+ *   You are free to use, modify, derive or otherwise extend for your own non-commercial purposes provided
+ *       1. No part of this software or design may be used to cause injury or death to humans or animals.
+ *       2. Use is non-commercial.
+ *       3. Credit is given to the author (i.e. portions © bechter.com), and provide a link to the original source.
+ *
+ */
+
+#include "DS2438.h"
+
+DS2438::DS2438(OneWire *ow, uint8_t *address) {
+    _ow = ow;
+    _address = address;
+};
+
+void DS2438::begin(uint8_t mode) {
+    _mode = mode & (DS2438_MODE_CHA | DS2438_MODE_CHB | DS2438_MODE_TEMPERATURE);
+    _temperature = 0;
+    _voltageA = 0.0;
+    _voltageB = 0.0;
+    _error = true;
+    _timestamp = 0;
+}
+
+void DS2438::update() {
+    uint8_t data[9];
+
+    _error = true;
+    _timestamp = millis();
+
+    if (_mode & DS2438_MODE_CHA || _mode == DS2438_MODE_TEMPERATURE) {
+        boolean doTemperature = _mode & DS2438_MODE_TEMPERATURE;
+        if (!startConversion(DS2438_CHA, doTemperature)) {
+            return;
+        }
+        if (!readPageZero(data))
+            return;
+        if (doTemperature) {
+            _temperature = (double)(((((int16_t)data[2]) << 8) | (data[1] & 0x0ff)) >> 3) * 0.03125;
+        }
+        if (_mode & DS2438_MODE_CHA) {
+            _voltageA = (((data[4] << 8) & 0x00300) | (data[3] & 0x0ff)) / 100.0;
+        }
+    }
+    if (_mode & DS2438_MODE_CHB) {
+        boolean doTemperature = _mode & DS2438_MODE_TEMPERATURE & !(_mode & DS2438_MODE_CHA);
+        if (!startConversion(DS2438_CHB, doTemperature)) {
+            return;
+        }
+        if (!readPageZero(data))
+            return;
+        if (doTemperature) {
+            _temperature = (double)(((((int16_t)data[2]) << 8) | (data[1] & 0x0ff)) >> 3) * 0.03125;
+        }
+        _voltageB = (((data[4] << 8) & 0x00300) | (data[3] & 0x0ff)) / 100.0;
+    }
+    _error = false;
+}
+
+double DS2438::getTemperature() {
+    return _temperature;
+}
+
+float DS2438::getVoltage(int channel) {
+    if (channel == DS2438_CHA) {
+        return _voltageA;
+    } else if (channel == DS2438_CHB) {
+        return _voltageB;
+    } else {
+        return 0.0;
+    }
+}
+
+boolean DS2438::isError() {
+    return _error;
+}
+
+unsigned long DS2438::getTimestamp() {
+    return _timestamp;
+}
+
+boolean DS2438::startConversion(int channel, boolean doTemperature) {
+    if (!selectChannel(channel))
+        return false;
+    _ow->reset();
+    _ow->select(_address);
+    if (doTemperature) {
+        _ow->write(DS2438_TEMPERATURE_CONVERSION_COMMAND, 0);
+        delay(DS2438_TEMPERATURE_DELAY);
+        _ow->reset();
+        _ow->select(_address);
+    }
+    _ow->write(DS2438_VOLTAGE_CONVERSION_COMMAND, 0);
+    delay(DS2438_VOLTAGE_CONVERSION_DELAY);
+    return true;
+}
+
+boolean DS2438::selectChannel(int channel) {
+    uint8_t data[9];
+    if (readPageZero(data)) {
+        if (channel == DS2438_CHB)
+            data[0] = data[0] | 0x08;
+        else
+            data[0] = data[0] & 0xf7;
+        writePageZero(data);
+        return true;
+    }
+    return false;
+}
+
+void DS2438::writePageZero(uint8_t *data) {
+    _ow->reset();
+    _ow->select(_address);
+    _ow->write(DS2438_WRITE_SCRATCHPAD_COMMAND, 0);
+    _ow->write(DS2438_PAGE_0, 0);
+    for (int i = 0; i < 8; i++)
+        _ow->write(data[i], 0);
+    _ow->reset();
+    _ow->select(_address);
+    _ow->write(DS2438_COPY_SCRATCHPAD_COMMAND, 0);
+    _ow->write(DS2438_PAGE_0, 0);
+}
+
+boolean DS2438::readPageZero(uint8_t *data) {
+    _ow->reset();
+    _ow->select(_address);
+    _ow->write(DS2438_RECALL_MEMORY_COMMAND, 0);
+    _ow->write(DS2438_PAGE_0, 0);
+    _ow->reset();
+    _ow->select(_address);
+    _ow->write(DS2438_READ_SCRATCHPAD_COMMAND, 0);
+    _ow->write(DS2438_PAGE_0, 0);
+    for (int i = 0; i < 9; i++)
+        data[i] = _ow->read();
+    return _ow->crc8(data, 8) == data[8];
+}
+
+

DS2438.h

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+/*
+ *   DS2438.h
+ *
+ *   by Joe Bechter
+ *
+ *   (C) 2012, bechter.com
+ *
+ *   All files, software, schematics and designs are provided as-is with no warranty.
+ *   All files, software, schematics and designs are for experimental/hobby use.
+ *   Under no circumstances should any part be used for critical systems where safety,
+ *   life or property depends upon it. You are responsible for all use.
+ *   You are free to use, modify, derive or otherwise extend for your own non-commercial purposes provided
+ *       1. No part of this software or design may be used to cause injury or death to humans or animals.
+ *       2. Use is non-commercial.
+ *       3. Credit is given to the author (i.e. portions © bechter.com), and provide a link to the original source.
+ *
+ */
+
+#ifndef DS2438_h
+#define DS2438_h
+
+#include <Arduino.h>
+#include <OneWire.h>
+
+#define DS2438_TEMPERATURE_CONVERSION_COMMAND 0x44
+#define DS2438_VOLTAGE_CONVERSION_COMMAND 0xb4
+#define DS2438_WRITE_SCRATCHPAD_COMMAND 0x4e
+#define DS2438_COPY_SCRATCHPAD_COMMAND 0x48
+#define DS2438_READ_SCRATCHPAD_COMMAND 0xbe
+#define DS2438_RECALL_MEMORY_COMMAND 0xb8
+#define DS2438_PAGE_0 0x00
+
+#define DS2438_CHA 0
+#define DS2438_CHB 1
+
+#define DS2438_MODE_CHA 0x01
+#define DS2438_MODE_CHB 0x02
+#define DS2438_MODE_TEMPERATURE 0x04
+
+#define DS2438_TEMPERATURE_DELAY 10
+#define DS2438_VOLTAGE_CONVERSION_DELAY 8
+
+class DS2438 {
+    public:
+        DS2438(OneWire *ow, uint8_t *address);
+        void begin(uint8_t mode=(DS2438_MODE_CHA | DS2438_MODE_CHB | DS2438_MODE_TEMPERATURE));
+        void update();
+        double getTemperature();
+        float getVoltage(int channel=DS2438_CHA);
+        boolean isError();
+        unsigned long getTimestamp();
+    private:
+        OneWire *_ow;
+        uint8_t *_address;
+        uint8_t _mode;
+        double _temperature;
+        float _voltageA;
+        float _voltageB;
+        unsigned long _timestamp;
+        boolean _error;
+        boolean startConversion(int channel, boolean doTemperature);
+        boolean selectChannel(int channel);
+        void writePageZero(uint8_t *data);
+        boolean readPageZero(uint8_t *data);
+};
+
+#endif

LICENSE

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+Copyright 2013, bechter.com - All Rights Reserved
+
+  1. All files, software, schematics and designs are provided as-is with no warranty.
+  2. All files, software, schematics and designs are for experimental/hobby use.
+     Under no circumstances should any part be used for critical systems where safety,
+     life or property depends upon it. You are responsible for all use.
+  3. You are free to use, modify, derive or otherwise extend for your own non-commercial purposes provided
+  1. No part of this software or design may be used to cause injury or death to humans or animals.
+  2. Use is non-commercial.
+  3. Credit is given to the author (i.e. portions © bechter.com),
+     and provide a link to this site (http://projects.bechter.com).
+
+

README.txt

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+DS2438 Arduino OneWire Library
+
+To install, copy the DS2438 folder structure to your Arduino libraries folder.
+
+Requires Arduino 1.0 or greater and OneWire Arduino library (see http://playground.arduino.cc/Learning/OneWire).
+
+For additional information see http://projects.bechter.com
+

examples/DS2438Humidity/DS2438Humidity.ino

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+/*
+ *   DS2438Humidity
+ *
+ *   This example demonstrates the use of the DS2438 Library and the Arduino OneWire library
+ *   to read a relative humidity sensor that uses a Dallas Semiconductor DS2438 battery monitor.
+ *   This example is for a 1-Wire device similar to the HobbyBoards H3-R1-A humidity sensor.
+ *
+ *   by Joe Bechter
+ *
+ *   (C) 2012, bechter.com
+ *
+ *   All files, software, schematics and designs are provided as-is with no warranty.
+ *   All files, software, schematics and designs are for experimental/hobby use.
+ *   Under no circumstances should any part be used for critical systems where safety,
+ *   life or property depends upon it. You are responsible for all use.
+ *   You are free to use, modify, derive or otherwise extend for your own non-commercial purposes provided
+ *       1. No part of this software or design may be used to cause injury or death to humans or animals.
+ *       2. Use is non-commercial.
+ *       3. Credit is given to the author (i.e. portions © bechter.com), and provide a link to the original source.
+ *
+ */
+
+#include <Arduino.h>
+#include <OneWire.h>
+#include <DS2438.h>
+
+// define the Arduino digital I/O pin to be used for the 1-Wire network here
+const uint8_t ONE_WIRE_PIN = 2;
+
+// define the 1-Wire address of the DS2438 battery monitor here (lsb first)
+uint8_t DS2438_address[] = { 0x26, 0x45, 0xe6, 0xf7, 0x00, 0x00, 0x00, 0x4e };
+
+OneWire ow(ONE_WIRE_PIN);
+DS2438 ds2438(&ow, DS2438_address);
+
+float temperature;
+float heatindex;
+float dewpoint;
+float humidity;
+
+void setup() {
+    Serial.begin(9600);
+    ds2438.begin();
+}
+
+void loop() {
+    ds2438.update();
+    if (ds2438.isError() || ds2438.getVoltage(DS2438_CHA) == 0.0) {
+        Serial.println("Error reading from DS2438 device");
+    } else {
+        temperature = ds2438.getTemperature();
+        heatindex = temperature;
+        float rh = (ds2438.getVoltage(DS2438_CHA) / ds2438.getVoltage(DS2438_CHB) - 0.16) / 0.0062;
+        humidity = (float)(rh / (1.0546 - 0.00216 * temperature));
+        if (humidity < 0.0) {
+            humidity = 0.0;
+        } else if (humidity > 100.0) {
+            humidity = 100.0;
+        }
+        float tempK = temperature + 273.15;
+        dewpoint = tempK / ((-0.0001846 * log(humidity / 100.0) * tempK) + 1.0) - 273.15;
+        if (temperature >= 26.7 && humidity >= 40.0) {
+            float t = temperature * 9.0 / 5.0 + 32.0; // heat index formula assumes degF
+            rh = humidity;
+            float heatindexF = -42.38 + 2.049 * t + 10.14 * rh + -0.2248 * t * rh + -0.006838 * t * t
+                               + -0.05482 * rh * rh + 0.001228 * t * t * rh + 0.0008528 * t * rh * rh
+                               + -0.00000199 * t * t * rh * rh;
+            heatindex = (heatindexF - 32.0) * 5.0 / 9.0;
+        }
+        if (heatindex < temperature)
+            heatindex = temperature;
+    }
+    Serial.print("Temperature = ");
+    Serial.print(temperature, 1);
+    Serial.print("C (");
+    Serial.print(temperature * 9.0 / 5.0 + 32.0, 1);
+    Serial.print("F), Heat Index = ");
+    Serial.print(heatindex, 1);
+    Serial.print("C (");
+    Serial.print(heatindex * 9.0 / 5.0 + 32.0, 1);
+    Serial.print("F), Dewpoint = ");
+    Serial.print(dewpoint, 1);
+    Serial.print("C (");
+    Serial.print(dewpoint * 9.0 / 5.0 + 32.0, 1);
+    Serial.print("F), Relative Humidity = ");
+    Serial.print(humidity, 0);
+    Serial.println("%.");
+    delay(500);
+}

examples/DS2438TemperatureAndVoltage/DS2438TemperatureAndVoltage.ino

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+/*
+ *   DS2438TemperatureAndVoltage
+ *
+ *   This example demonstrates the use of the DS2438 Library to read temperature and
+ *   voltage from a Dallas Semiconductor DS2438 battery monitor using the Arduino
+ *   OneWire library.
+ *
+ *   by Joe Bechter
+ *
+ *   (C) 2012, bechter.com
+ *
+ *   All files, software, schematics and designs are provided as-is with no warranty.
+ *   All files, software, schematics and designs are for experimental/hobby use.
+ *   Under no circumstances should any part be used for critical systems where safety,
+ *   life or property depends upon it. You are responsible for all use.
+ *   You are free to use, modify, derive or otherwise extend for your own non-commercial purposes provided
+ *       1. No part of this software or design may be used to cause injury or death to humans or animals.
+ *       2. Use is non-commercial.
+ *       3. Credit is given to the author (i.e. portions © bechter.com), and provide a link to the original source.
+ *
+ */
+
+#include <Arduino.h>
+#include <OneWire.h>
+#include <DS2438.h>
+
+// define the Arduino digital I/O pin to be used for the 1-Wire network here
+const uint8_t ONE_WIRE_PIN = 2;
+
+// define the 1-Wire address of the DS2438 battery monitor here (lsb first)
+uint8_t DS2438_address[] = { 0x26, 0x45, 0xe6, 0xf7, 0x00, 0x00, 0x00, 0x4e };
+
+OneWire ow(ONE_WIRE_PIN);
+DS2438 ds2438(&ow, DS2438_address);
+
+void setup() {
+    Serial.begin(9600);
+    ds2438.begin();
+}
+
+void loop() {
+    ds2438.update();
+    if (ds2438.isError()) {
+        Serial.println("Error reading from DS2438 device");
+    } else {
+        Serial.print("Temperature = ");
+        Serial.print(ds2438.getTemperature(), 1);
+        Serial.print("C, Channel A = ");
+        Serial.print(ds2438.getVoltage(DS2438_CHA), 1);
+        Serial.print("v, Channel B = ");
+        Serial.print(ds2438.getVoltage(DS2438_CHB), 1);
+        Serial.println("v.");
+    }
+    delay(500);
+}