Revision 3:ef0e12857e30, committed 2014-02-24

Comitter:

passelin

Date:

Mon Feb 24 15:44:51 2014 +0000

Parent:

2:bbe1253008e6

Child:

4:21b8959e8b71

Commit message:

accelero ajout?

Changed in this revision

--- a/main.cpp	Sat Feb 22 23:46:06 2014 +0000
+++ b/main.cpp	Mon Feb 24 15:44:51 2014 +0000
@@ -1,6 +1,23 @@
 #include "mbed.h"
+#include <sstream>
 #include <string>
- 
+#include "ConfigFile.h"
+
+//#define HIGH_RES        10  // Uncomment to operate the accelerometer in HIGH RESOLUTION(12 bits) otherwise, it would operates in LOW RESOLUTION(8 bits)
+
+#define DELAY           0.25    
+
+#define MMA8452_WRITE_ADDRESS 0x3A
+#define MMA8452_READ_ADDRESS  0x3B
+#define WHO_AM_I        0x0D
+#define OUT_X_MSB       0x01
+#define OUT_X_LSB       0x02
+#define OUT_Y_MSB       0x03
+#define OUT_Y_LSB       0x04
+#define OUT_Z_MSB       0x05
+#define OUT_Z_LSB       0x06
+#define CTRL_REG1       0x2A 
+#define CTRL_REG2       0x2B
 
 #define ACCEL 0x01
 #define PUSHBOUTON 0x02
@@ -10,15 +27,97 @@
 DigitalOut reset(p8);
 Serial pc(USBTX, USBRX);
 Serial xbee(p13, p14);
-string data = "allo bonjour";
+I2C i2c(p9, p10);            // I2C port (sda, scl)
+
+//LocalFileSystem local("local");
+ConfigFile cfg;
+
+string AccelData;
 
- // 7E 00 0F 10 01 00 13 A2 00 40 8B 41 98 00 00 00 00 33 62
- // 7E 00 10 10 01 00 13 A2 00 40 8B 41 98 00 00 00 00 33 33 2F
+void xbee_init()
+{
+    reset = 0;
+    wait_ms(400);
+    reset = 1;
+}
+
+char i2c_read_reg(char address)
+{   
+    // Read from selected register adress
+    i2c.start();                                         
+    i2c.write(MMA8452_WRITE_ADDRESS);   
+    i2c.write(address);                 
+    i2c.start();                        
+    i2c.write(MMA8452_READ_ADDRESS);    
+    char data = i2c.read(0);            
+    i2c.stop();                         
  
- void checksum()
+    // return the data readed
+    return data;   
+}
+
+bool initAccel()
+{
+    // Start I2C communication   
+    char data = i2c_read_reg(WHO_AM_I);
+    if(data != 0x2A)
+    {
+        return false;
+    }
+    
+    // Set accelerometer in Low Noise Low Power mode
+    i2c.start();                           
+    i2c.write(MMA8452_WRITE_ADDRESS); 
+    i2c.write(CTRL_REG2); 
+    i2c.write(0x01); 
+    i2c.stop(); 
+    
+    // Set accelerometer in active mode
+    i2c.start();                           
+    i2c.write(MMA8452_WRITE_ADDRESS); 
+    i2c.write(CTRL_REG1); 
+    i2c.write(0x01); 
+    i2c.stop();  
+    
+    return true;     
+}
+
+
+unsigned short getAccelValue(char MSB_addr, char LSB_addr)
 {
+    unsigned short retValue; 
+    unsigned char msb;
+
+    msb = i2c_read_reg(MSB_addr);           // Read MSB data from MSB register
+
+#ifdef HIGH_RES // Use LSB only in HIGH RESOLUTION mode.
+    unsigned char lsb;
+    lsb = i2c_read_reg(LSB_addr);           // Read LSB data from MSB register
+    retValue = (msb << 4);                  // Shift the data by 4 to the left in order to rebuild the 12 bits data ( MSB MSB MSB MSB MSB MSB MSB MSB 0 0 0 0 )
+    retValue = ((lsb >> 4) | retValue);     // Shift the data by 4 to the right in order to keep only the 4 first bits and rebuild the 12 bits data ( MSB MSB MSB MSB MSB MSB MSB MSB LSB LSB LSB LSB)
+    retValue = retValue*36000/4096; 
+          
+#endif
+#ifndef HIGH_RES  // In LOW RESOLUTION mode, we use only the MSB
+    retValue = msb;
+    retValue = retValue*36000/256;
+#endif
+       
+    if(retValue > 19000) // value cannot be between 90deg and 270deg.
+    {
+        retValue = 36000 - retValue;
+    }
+    else if(retValue > 9000)
+    {
+        retValue = 9000 - (retValue - 9000);
+    }
     
+    // Invert the angle value to use the honrizontal axis as reference instead of z axis
+    retValue = 9000 - retValue;
+    
+    return retValue;
 }
+
 void xbee_transmit(char type, string data)
 {
     char checkSum = 0;
@@ -56,19 +155,29 @@
 
 int main() 
 {
+    unsigned short z; 
+    
+    xbee_init();
+    initAccel();
+    
     myled = 1;
     myled2 = 1;
-    reset = 0;
-    wait_ms(400);
-    reset = 1;
-    myled = 0;
-    myled2 = 0;
+    
+    wait(4);
+    
     while(1) 
     {
-        wait(4);
-        xbee_transmit(ACCEL, data);
+        // Get z angle from the accelerometer
+        z= getAccelValue(OUT_Z_MSB, OUT_Z_LSB);
+        std::stringstream out;
+        out << z;   
+        AccelData = out.str();
+        
+        //Transmit to coordonitator
+        xbee_transmit(ACCEL, AccelData);
        
-       
+
+         
        /* if(xbee.readable())
         {
             pc.putc(xbee.getc());