Revision 5:c43505b5bc31, committed 2013-02-27

Comitter:

maclobdell

Date:

Wed Feb 27 03:58:53 2013 +0000

Parent:

4:c4d879a39775

Child:

6:2b68086a26ff

Commit message:

1st working version

Changed in this revision

--- a/MMA8451Q.cpp	Fri Oct 12 11:35:07 2012 +0000
+++ b/MMA8451Q.cpp	Wed Feb 27 03:58:53 2013 +0000
@@ -26,39 +26,167 @@
 
 #define UINT14_MAX        16383
 
-MMA8451Q::MMA8451Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) {
-    // activate the peripheral
-    uint8_t data[2] = {REG_CTRL_REG_1, 0x01};
-    writeRegs(data, 2);
+// Set the scale below either 2, 4 or 8
+#define SCALE  2;  // Sets full-scale range to +/-2, 4, or 8g. Used to calc real g values.
+// Set the output data rate below. Value should be between 0 and 7
+#define DATARATE = 0;  // 0=800Hz, 1=400, 2=200, 3=100, 4=50, 5=12.5, 6=6.25, 7=1.56
+
+extern Serial pc;
+
+MMA8451Q::MMA8451Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr)
+{
+  //need to clear registers before writing because they only get cleared on a power cycle
+  //need to implement that
+  
+   modeStandby();  // Must be in standby to change registers     
+
+/*    pc.printf("++++++++++++++++++\n\r");
+    uint8_t myRegs = 0;  
+    for(uint8_t i = 0; i<0x31;i++)
+    {
+      myRegs = readRegister(i);
+      pc.printf("%x: %x\n\r",i,myRegs);   
+    }
+    pc.printf("+==+==+==++===+=+\n\r");
+*/
+  
+  // Set up the full scale range to 2, 4, or 8g.
+  //if ((fsr==2)||(fsr==4)||(fsr==8))
+    writeRegister(0x0E, 0);  //SCALE >> 2);      
+  //else
+  //  writeRegister(0x0E, 0);
+
+  // Setup the 3 data rate bits, from 0 to 7
+  writeRegister(0x2A, readRegister(0x2A) & ~(0x38));
+  //if (DATARATE <= 7)
+  // writeRegister(0x2A, readRegister(0x2A) | (DATARATE << 3));  
+
+  // Set up portrait/landscap registers - 4 steps:
+  // 1. Enable P/L
+  // 2. Set the back/front angle trigger points (z-lock)
+  // 3. Set the threshold/hysteresis angle
+  // 4. Set the debouce rate
+  // For more info check out this app note: http://cache.freescale.com/files/sensors/doc/app_note/AN4068.pdf
+if(MMA8451Q_ENABLE_ORIENTATION)
+{
+pc.printf("setting orientation configuraiton \n\r");
+
+  writeRegister(0x11, 0x40);  // 1. Enable P/L
+  writeRegister(0x13, 0x44);  // 2. 29deg z-lock (don't think this register is actually writable)
+  writeRegister(0x14, 0x84);  // 3. 45deg thresh, 14deg hyst (don't think this register is writable either)
+  writeRegister(0x12, 0x50);  // 4. debounce counter at 100ms (at 800 hz)
+}
+
+  /* Set up single and double tap - 5 steps:
+   1. Set up single and/or double tap detection on each axis individually.
+   2. Set the threshold - minimum required acceleration to cause a tap.
+   3. Set the time limit - the maximum time that a tap can be above the threshold
+   4. Set the pulse latency - the minimum required time between one pulse and the next
+   5. Set the second pulse window - maximum allowed time between end of latency and start of second pulse
+   for more info check out this app note: http://cache.freescale.com/files/sensors/doc/app_note/AN4072.pdf */
+if(  MMA8451Q_ENABLE_DOUBLE_Z_TAP | MMA8451Q_ENABLE_SINGLE_Z_TAP)
+{
+  //writeRegister(0x21, 0x7F);  // 1. enable single/double taps on all axes
+  // writeRegister(0x21, 0x55);  // 1. single taps only on all axes
+  // writeRegister(0x21, 0x6A);  // 1. double taps only on all axes
+ pc.printf("setting tap configuraiton \n\r");
+ 
+ 
+ if(MMA8451Q_ENABLE_DOUBLE_Z_TAP)
+     writeRegister(0x21, readRegister(0x21) | 0x60);  // 1. enable double taps on Z axes
+ if(MMA8451Q_ENABLE_SINGLE_Z_TAP)
+      writeRegister(0x21, readRegister(0x21) | 0x50);  // 1. enable single taps on Z axes
+ 
+ 
+ /* set up the Tap threshold and timing */
+ //not doing x,y taps
+//  writeRegister(0x23, 0x20);  // 2. x thresh at 2g, multiply the value by 0.0625g/LSB to get the threshold
+//  writeRegister(0x24, 0x20);  // 2. y thresh at 2g, multiply the value by 0.0625g/LSB to get the threshold
+//  writeRegister(0x25, 0x08);  // 2. z thresh at .5g, multiply the value by 0.0625g/LSB to get the threshold
+  writeRegister(0x25, 0x04);  // 2. z thresh at ?g, multiply the value by 0.0625g/LSB to get the threshold  
+  writeRegister(0x26, 0x30);  // 3. 30ms time limit at 800Hz odr, this is very dependent on data rate, see the app note
+  writeRegister(0x27, 0xA0);  // 4. 200ms (at 800Hz odr) between taps min, this also depends on the data rate
+  writeRegister(0x28, 0xFF);  // 5. 318ms (max value) between taps max
+}
+
+if(  MMA8451Q_ENABLE_DOUBLE_Z_TAP | MMA8451Q_ENABLE_SINGLE_Z_TAP | MMA8451Q_ENABLE_DATAREADY | MMA8451Q_ENABLE_ORIENTATION)
+{
+  pc.printf("setting up interrupts \n\r");
+
+  // Set up interrupt 1 and 2
+  
+  // writeRegister(0x2C, 0x02);  // Active high, push-pull interrupts
+   writeRegister(0x2C, 0x01);  // Active low, push-pull interrupts
+  
+  //writeRegister(0x2D, 0x19);  // DRDY, P/L and tap ints enabled
+//  writeRegister(0x2D, 0x9);  // DRDY, tap ints enabled
+
+if(  MMA8451Q_ENABLE_DATAREADY)
+{//enable data ready interrupts
+   writeRegister(0x2D, readRegister(0x2D)| 0x1);  // DRDY ints enabled
+}  
+if(  MMA8451Q_ENABLE_DOUBLE_Z_TAP | MMA8451Q_ENABLE_SINGLE_Z_TAP)
+{//enable tap interrupts
+   writeRegister(0x2D, readRegister(0x2D)| 0x8);  // taps ints enabled
+}
+if(  MMA8451Q_ENABLE_ORIENTATION)
+{//enable orientation interrupts
+   writeRegister(0x2D, readRegister(0x2D)| 0x10);  // orientation ints enabled
+}
+
+  writeRegister(0x2E, 0x01);  // DRDY on INT1, P/L and taps on INT2
+  
+}
+
+  modeActive();  // Set to active to start reading
+
+/*
+    pc.printf("Print Registers\n\r");
+    pc.printf("---------------\n\r");
+     myRegs = 0;  
+    for(uint8_t i = 0; i<0x31;i++)
+    {
+      myRegs = readRegister(i);
+      pc.printf("%x: %x\n\r",i,myRegs);   
+    }
+    pc.printf("================\n\r");
+*/
+     
 }
 
 MMA8451Q::~MMA8451Q() { }
 
-uint8_t MMA8451Q::getWhoAmI() {
+uint8_t MMA8451Q::getWhoAmI()
+{
     uint8_t who_am_i = 0;
     readRegs(REG_WHO_AM_I, &who_am_i, 1);
     return who_am_i;
 }
 
-float MMA8451Q::getAccX() {
+float MMA8451Q::getAccX()
+{
     return (float(getAccAxis(REG_OUT_X_MSB))/4096.0);
 }
 
-float MMA8451Q::getAccY() {
+float MMA8451Q::getAccY()
+{
     return (float(getAccAxis(REG_OUT_Y_MSB))/4096.0);
 }
 
-float MMA8451Q::getAccZ() {
+float MMA8451Q::getAccZ()
+{
     return (float(getAccAxis(REG_OUT_Z_MSB))/4096.0);
 }
 
-void MMA8451Q::getAccAllAxis(float * res) {
+void MMA8451Q::getAccAllAxis(float * res)
+{
     res[0] = getAccX();
     res[1] = getAccY();
     res[2] = getAccZ();
 }
 
-int16_t MMA8451Q::getAccAxis(uint8_t addr) {
+int16_t MMA8451Q::getAccAxis(uint8_t addr)
+{
     int16_t acc;
     uint8_t res[2];
     readRegs(addr, res, 2);
@@ -70,12 +198,62 @@
     return acc;
 }
 
-void MMA8451Q::readRegs(int addr, uint8_t * data, int len) {
+void MMA8451Q::readRegs(int addr, uint8_t * data, int len)
+{
     char t[1] = {addr};
     m_i2c.write(m_addr, t, 1, true);
     m_i2c.read(m_addr, (char *)data, len);
 }
 
-void MMA8451Q::writeRegs(uint8_t * data, int len) {
+void MMA8451Q::writeRegs(uint8_t * data, int len)
+{
     m_i2c.write(m_addr, (char *)data, len);
 }
+
+void MMA8451Q::writeRegister(uint8_t reg, uint8_t data)
+{  //write to single register
+     uint8_t wdata[2] = {reg, data};
+     m_i2c.write(m_addr, (char *)wdata, 2);
+     
+}
+uint8_t MMA8451Q::readRegister(uint8_t reg)
+{  //read single register
+
+    uint8_t data;
+    readRegs(reg, &data, 1);   
+    
+    return data; 
+}
+
+// Sets the MMA8452 to standby mode.
+// It must be in standby to change most register settings
+void MMA8451Q::modeStandby(void)
+{
+  uint8_t c = readRegister(0x2A);
+  writeRegister(0x2A, c & ~(0x01));
+}
+
+// Sets the MMA8452 to active mode.
+// Needs to be in this mode to output data
+void MMA8451Q::modeActive(void)
+{
+ int8_t c = readRegister(0x2A);
+  writeRegister(0x2A, c | 0x01);
+}
+
+uint8_t MMA8451Q::direction(void)
+{
+  uint8_t pl = readRegister(0x10);  // Reads the PL_STATUS register
+  return pl;
+
+}
+uint8_t MMA8451Q::tapSource(void)
+{
+  uint8_t source = readRegister(0x22);  // Reads the PULSE_SRC register
+  return source;
+}
+uint8_t MMA8451Q::intSource(void)
+{
+  uint8_t  source = readRegister(0x0C);  // Read the interrupt source reg.
+  return source;
+}

--- a/MMA8451Q.h	Fri Oct 12 11:35:07 2012 +0000
+++ b/MMA8451Q.h	Wed Feb 27 03:58:53 2013 +0000
@@ -21,6 +21,12 @@
 
 #include "mbed.h"
 
+//just supporting Z taps in the code, not X, Y yet
+#define MMA8451Q_ENABLE_DOUBLE_Z_TAP  0
+#define MMA8451Q_ENABLE_SINGLE_Z_TAP  1
+#define MMA8451Q_ENABLE_ORIENTATION   0
+#define MMA8451Q_ENABLE_DATAREADY     0
+
 /**
 * MMA8451Q accelerometer example
 *
@@ -98,13 +104,19 @@
    */
   void getAccAllAxis(float * res);
 
+  uint8_t direction(void);
+  uint8_t tapSource(void);
+  uint8_t intSource(void);
+  
 private:
   I2C m_i2c;
   int m_addr;
   void readRegs(int addr, uint8_t * data, int len);
   void writeRegs(uint8_t * data, int len);
   int16_t getAccAxis(uint8_t addr);
-
+  void writeRegister(uint8_t reg, uint8_t data);
+  uint8_t readRegister(uint8_t reg);
+  void modeStandby(void);
+  void modeActive(void);
 };
-
 #endif