Diff: SRF08.cpp

Revision:

2:ca82f89f415d

Parent:

1:76fb116fa28d

Child:

3:c43cd24ec7e7

--- a/SRF08.cpp	Tue Jul 10 08:48:02 2012 +0000
+++ b/SRF08.cpp	Wed Jul 11 07:53:50 2012 +0000
@@ -1,6 +1,5 @@
-
 /*
-Copyright (c) 2010 Chris Styles ( chris dot styles at mbed dot org )
+Copyright (c) 2012 Brent Dekker
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -25,31 +24,16 @@
 
 /*
  * Constructor: SRF08
- * Args:        PinName sda: Data pin of I2C bus to which module is connected
- *              PinName scl: Clock pin of I2C bus to which module is connected
- *              int addr:    address of module on the I2C bus
+ * Args:
  * Returns:     void
  * Description: Creates an instance of the SRF08 to communicate with a sRF08 module
  */
-SRF08::SRF08(PinName sda, PinName scl, int addr) :
-        m_i2c(sda, scl), m_addr(addr), rangeBuf(), rangeBufIndex(0) {
-    char cmd[2];
-    // Set up SRF08 max range and receiver sensitivity over I2C bus
-    cmd[0] = 0x02;                          // Range register
-    cmd[1] = 0xFF;
-    m_i2c.write(m_addr, cmd, 2);
-    cmd[0] = 0x01;                          // Receiver gain register
-    cmd[1] = 0x1F;                          // Set max receiver gain
-    m_i2c.write(m_addr, cmd, 2);
-}
-
-/*
- * Destructor:  ~SRF08
- * Args:        void
- * Returns:     void
- * Description: Destroys instance of SRF08 class
- */
-SRF08::~SRF08() {
+SRF08::SRF08(PinName SDA, PinName SCL, int i2cAddress) :
+        i2cMod(SDA, SCL), 
+        i2cAddress(i2cAddress), 
+        rangeTimeout(), 
+        rangingBusy(false), 
+        debugPC(USBTX, USBRX) {
 
 }
 
@@ -59,11 +43,14 @@
  * Returns:     void
  * Description: Sends command to module to start ranging.
  */
-void startRanging() {
-    // Send Tx burst command over I2C bus
-    cmd[0] = 0x00;                      // Command register
-    cmd[1] = 0x51;                      // Ranging results in cm
-    m_i2c.write(m_addr, cmd, 2);        // Send ranging burst
+void SRF08::startRanging() {
+    //Create a two byte command. The first first byte is the register address
+    // on the SRF08 to write to. The second byte is the command which is written
+    // to that address ("Start ranging in cm" in this case).
+    const char command[] = {0x00, 0x51};
+    i2cMod.write(i2cAddress, command, 2);
+    this->rangingBusy = true;
+    rangeTimeout.attach(this, &SRF08::setRangingFinished, 0.07);
 }
 
 /*
@@ -72,12 +59,8 @@
  * Returns:     Bool: whether ranging is finished
  * Description: Checks if the ranging process on the module is finished
  */
-bool rangingFinished() {
-    char cmd = 0x00; //Software revision register
-    char echo;
-    m_i2c.write(m_addr, cmd, 1, 1); //Send address of software rev register
-    m_i2c.read(m_addr, echo, 1);    //Read 1 byte echo result
-    if (echo == 0xFF) return false;
+bool SRF08::rangingFinished() {
+    if(this->rangingBusy) return false;
     return true;
 }
 
@@ -87,63 +70,31 @@
  * Returns:     int range
  * Description: Range in cm. This function should only be called when ranging is finished, otherwise previous value is returned
  */
-void getRange() {
-    char cmd[2];
-    char echo[2];
-    // Read range over I2C bus
-    cmd[0] = 0x02;                      // Address of first echo
-    m_i2c.write(m_addr, cmd, 1, 1);     // Send address of first echo
-    m_i2c.read(m_addr, echo, 2);        // Read two-byte echo result
-    // Generate PWM mark/space ratio from range data
-    int range = (echo[0]<<8)+echo[1];
-    return range;
+int SRF08::getRange() {
+    //while (!rangingFinished() ) wait(0.01);   //Wait until ranging is finished
+    const char command[]  = {0x02};           //Address of range register
+    char response[] = {0x00, 0x00};
+    i2cMod.write(i2cAddress, command, 1, 1);  //Send command
+    i2cMod.read(i2cAddress, response, 2);     //Read 16bits result
+    int range = (response[0]<<8)+response[1]; //Shift two bytes into int
+    return range;                             //Return int range
 }
 
 /*
- * Function:    readRange
+ * Function:    readLightIntensity
  * Args:        void
- * Returns:     int range
- * Description: Reads the range register and converts it to a usable value
+ * Returns:     int lightIntensity
+ * Description: Reads the lightIntensity from the module
+ *              The light intensity is updated if a range command is sent, so don't use
+ *              this function only
  */
-int SRF08::readRange() {
-    char cmd[2];
-    char echo[2];
-
-    // Get range data from SRF08
-    // Send Tx burst command over I2C bus
-    cmd[0] = 0x00;                      // Command register
-    cmd[1] = 0x51;                      // Ranging results in cm
-    m_i2c.write(m_addr, cmd, 2);        // Send ranging burst
-
-    wait(0.07);                         // Wait for return echo
-
-    // Read back range over I2C bus
-    cmd[0] = 0x02;                      // Address of first echo
-    m_i2c.write(m_addr, cmd, 1, 1);     // Send address of first echo
-    m_i2c.read(m_addr, echo, 2);        // Read two-byte echo result
-
-    // Generate PWM mark/space ratio from range data
-    int range = (echo[0]<<8)+echo[1];
-
-    return range;
-}
-
-/*
- * Function:    readBufRange
- * Args:        void
- * Returns:     int range
- * Description: Reads the range register, adds it to an array and converts it to a filtered value
- */
-//int SRF08::readBufRange() {
-
-//}
-
-int SRF08::getAverageBufRange() {
-    int total = 0;
-    for (int i = 0; i < RANGEBUFSIZE; i++) {
-        total += rangeBuf[i];
-    }
-    return (int)total/RANGEBUFSIZE;
+int SRF08::getLightIntensity() {
+    const char command[] = {0x01};           //Light intensity register
+    char response[] = {0x00};
+    i2cMod.write(i2cAddress, command, 1, 1); //Send command
+    i2cMod.read(i2cAddress, response, 1);    //Read response
+    int lightIntensity = response[0];
+    return lightIntensity;
 }
 
 /*
@@ -154,11 +105,18 @@
  *              The range is ((rangeVal x 43mm) + 43mm)
  *              The max range is about six meters
  */
-void SRF08::setRangeRegister(char rangeVal) {
-    char cmd[2];
-    cmd[0] = 0x02;          //Range register
-    cmd[1] = rangeVal;      //Range value
-    m_i2c.write(m_addr, cmd, 2);
+void SRF08::setRangeRegister(unsigned char rangeVal) {
+    while (!rangingFinished() ) wait(0.01);  //Wait until ranging is finished
+    char command[] = {0x02, rangeVal};       //Range register
+    i2cMod.write(i2cAddress, command, 2);    //Send command
+}
+
+
+//Function setMaxGainRegister
+void SRF08::setMaxGainRegister(unsigned char gainVal) {
+    while (!rangingFinished() ) wait(0.01);  //Wait until ranging is finished
+    char command[] = {0x01, gainVal};        //Max gain register
+    i2cMod.write(i2cAddress, command, 2);    //Send command
 }
 
 /*
@@ -169,37 +127,21 @@
  *                  The address can have the following values:
  *                      E0 | E2 | E4 | E6 ... FC | FE
  */
-void SRF08::setAddress(char address) {
-    char cmd[2];
-    cmd[0] = 0x00;
-    cmd[1] = 0xA0;
-    m_i2c.write(m_addr, cmd, 2);
-    cmd[1] = 0xAA;
-    m_i2c.write(m_addr, cmd, 2);
-    cmd[1] = 0xA5;
-    m_i2c.write(m_addr, cmd, 2);
-    cmd[1] = address;
-    m_i2c.write(m_addr, cmd, 2);
-    m_addr = address;
+void SRF08::setAddress(int address) {
+    //Send address change sequence
+    char command[] = {0x00, 0xA0};
+    i2cMod.write(i2cAddress, command, 2);
+    command[1] = 0xAA;
+    i2cMod.write(i2cAddress, command, 2);
+    command[1] = 0xA5;
+    i2cMod.write(i2cAddress, command, 2);
+    command[1] = address;
+    i2cMod.write(i2cAddress, command, 2);
+    //Save the updated address
+    i2cAddress = address;
 }
 
-/*
- * Function:    readLightIntensity
- * Args:        void
- * Returns:     int lightIntensity
- * Description: Reads the lightIntensity from the module
- *              The light intensity is updated if a range command is sent, so don't use
- *              this function only
- */
-int SRF08::readLightIntensity() {
-    char cmd[1];
-    char echo[1];
-
-    cmd[0] = 0x01;                      // Address of light intensity value
-    m_i2c.write(m_addr, cmd, 1, 1);     // Send address of first echo
-    m_i2c.read(m_addr, echo, 2);        // Read two-byte echo result
-
-    int lightIntensity = echo[0];
-
-    return lightIntensity;
-}
+//Small helper function
+void SRF08::setRangingFinished() {
+    this->rangingBusy = false;
+}
\ No newline at end of file