Revision 2:137b1af87cd0, committed 2015-02-13

Comitter:

gkumar

Date:

Fri Feb 13 17:20:53 2015 +0000

Parent:

1:fe48240c4b08

Commit message:

Gyro_MPU3300

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPU3300.h	Fri Feb 13 17:20:53 2015 +0000
@@ -0,0 +1,26 @@
+//MPU 3300 registers
+#define SMPLRT_DIV    0x19
+#define CONFIG        0x1A
+#define GYRO_CONFIG   0x1B
+#define GYRO_XOUT_H   0x43
+#define GYRO_XOUT_L   0x44
+#define GYRO_YOUT_H   0x45
+#define GYRO_YOUT_L   0x46
+#define GYRO_ZOUT_H   0x47
+#define GYRO_ZOUT_L   0x48
+#define USER_CTRL     0x6A
+#define PWR_MGMT_1    0x6B
+#define INT_ENABLE    0x38
+
+//MPU configuration bits
+#define READFLAG                  0x80
+#define DUMMYBIT                  0x00
+#define BITS_DLPF_CFG             0x07
+#define BITS_FS_SEL_3             0x08
+#define BITS_FS_SEL_4             0x10
+#define BIT_I2C_IF_DIS            0x10
+#define BITS_SMPLRT_DIV           0x00
+#define BIT_SLEEP                 0x40
+#define BIT_DATA_RDY_ENABLE       0x01
+#define BIT_DATA_RDY_INT          0x01
+#define BIT_CLKSEL_X              0x01

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Feb 13 17:20:53 2015 +0000
@@ -0,0 +1,175 @@
+#include<mbed.h>
+#include "MPU3300.h"                 //header file which includes all the register addresses and
+                    //Bit configuration of those registers
+SPI spi (PTD6,PTD7,PTD5) ;      // MOSI,MISO, CLOCK pins being used on                                                                                              //microcontroller(in order)     
+DigitalOut ssn (PTA13);         //Slave Select pin 
+Serial pc(USBTX,USBRX);
+InterruptIn dr(PTD2);       //Interrupt pin 
+Ticker tr;              //Ticker function to give values for limited amount of time
+uint8_t trFlag;         //ticker Flag 
+uint8_t drFlag;         //data-ready interrupt flag
+void trSub();               
+void drSub(); 
+void init_gyro();       
+void execute_gyro();
+int main(void)          
+{
+    init_gyro();                //Initializing Gyroscope registers and setting them to our required configuration
+    execute_gyro();         //Executing gyroscope for measuring angular rates
+    return 0;
+}
+void drSub()            //In this function we setting data-ready flag to 1              
+{
+    drFlag=1;
+}
+void trSub()                    //In this function we are setting ticker flag to 0
+{
+    trFlag=0;
+}
+void init_gyro()
+{
+    uint8_t response;               
+    ssn=1;                  //Deselecting the chip 
+    spi.format(8,3);                // Spi format is 8 bits, and clock mode 3 
+    spi.frequency(1000000);     //frequency to be set as 1MHz
+    drFlag=0;                   //Intially defining data-ready flag to be 0 
+    dr.mode(PullDown);          
+    dr.rise(&drSub);
+    __disable_irq();
+    
+/*Following the above mentioned algorithm for initializing the register and changing its configuration*/
+    ssn=0;                      //Selecting chip(Mpu-3300)
+    spi.write(USER_CTRL|READFLAG);   //sending USER_CTRL address with read bit
+    response=spi.write(DUMMYBIT);   //sending dummy bit to get default values of the register
+                        
+    ssn=1;                  //Deselecting the chip  
+    wait(0.1);                  //waiting according the product specifications 
+    
+    ssn=0;                  //again selecting the chip  
+    spi.write(USER_CTRL);           //sending USER_CTRL address without read bit 
+    spi.write(response|BIT_I2C_IF_DIS);  //disabling the I2C mode in the register
+    ssn=1;                  //deselecting the chip 
+    wait(0.1);                  // waiting for 100ms before going for another register 
+    
+    ssn=0;
+    spi.write(PWR_MGMT_1|READFLAG); //Power Management register-1 
+    response=spi.write(DUMMYBIT);
+    ssn=1;
+    wait(0.1);
+        
+    ssn=0;
+    spi.write(PWR_MGMT_1);
+    response=spi.write(response|BIT_CLKSEL_X);  //Selecting the X axis gyroscope as clock as mentioned above 
+    ssn=1;                          
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(GYRO_CONFIG|READFLAG); //sending GYRO_CONFIG address with read bit
+    response=spi.write(DUMMYBIT);
+    ssn=1;
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(GYRO_CONFIG); //sending GYRO_CONFIG address to write to register
+    spi.write(response&(~(BITS_FS_SEL_3|BITS_FS_SEL_4))); //selecting a full scale mode of +/=225 deg/sec
+    ssn=1;
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(CONFIG|READFLAG); //sending CONFIG address with read bit
+    response=spi.write(DUMMYBIT);
+    ssn=1;
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(CONFIG); //sending CONFIG address to write to register
+    spi.write(response|BITS_DLPF_CFG); //selecting a bandwidth of 42 hz and delay of 4.8ms
+    ssn=1;
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(SMPLRT_DIV|READFLAG); //sending SMPLRT_DIV address with read bit
+    response=spi.write(DUMMYBIT);
+    ssn=1;
+    wait(0.1);
+        
+    ssn=0;
+    spi.write(SMPLRT_DIV); //sending SMPLRT_DIV address to write to register
+    spi.write(response&BITS_SMPLRT_DIV); //setting the sampling rate division to be 0 to make sample rate = gyroscopic output rate
+    ssn=1;
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(INT_ENABLE|READFLAG);       //sending address of INT_ENABLE with readflag
+    response=spi.write(DUMMYBIT);              //sending dummy byte to get the default values of the
+                                                                          // regiser
+    ssn=1;   
+    wait(0.1);
+    
+    ssn=0;
+    spi.write(INT_ENABLE);                           //sending INT_ENABLE address to write to register
+    spi.write(response|BIT_DATA_RDY_ENABLE);  //Enbling data ready interrupt
+    ssn=1;
+    wait(0.1);
+    
+    __enable_irq();
+}
+
+void execute_gyro()
+{
+    uint8_t response;
+    uint8_t MSB,LSB;
+    int16_t bit_data;
+    float data[3],error[3]={0,0,0}; //declaring error array to add to the values when required
+    float senstivity = 145.6;     //senstivity is 145.6 for full scale mode of +/-225 deg/sec
+    ssn=0;
+    spi.write(PWR_MGMT_1|READFLAG); //sending address of INT_ENABLE with readflag
+    response=spi.write(DUMMYBIT); //
+    ssn=1;
+    wait(0.1);
+        
+    ssn=0;
+    spi.write(PWR_MGMT_1); //sending PWR_MGMT_1 address to write to register
+    response=spi.write(response&(~(BIT_SLEEP))); //waking up the gyroscope from sleep
+    ssn=1;
+    wait(0.1);
+    
+    trFlag=1;
+    tr.attach(&trSub,1); //executes the function trSub afer 1sec
+    while(trFlag)
+    {
+        if(drFlag==1)
+        {
+            ssn=0;
+            spi.write(GYRO_XOUT_H|READFLAG); //sending address of PWR_MGMT_1 with readflag
+            for(int i=0;i<3;i++)
+            {
+                MSB = spi.write(DUMMYBIT); //reading the MSB values of x,y and z respectively
+                LSB = spi.write(DUMMYBIT); //reading the LSB values of x,y and z respectively
+                bit_data= ((int16_t)MSB<<8)|LSB; //concatenating to get 16 bit 2's complement of the required gyroscope values
+                data[i]=(float)bit_data;
+                data[i]=data[i]/senstivity; //dividing with senstivity to get the readings in deg/sec
+                data[i]+=error[i]; //adding with error to remove offset errors
+            }
+            ssn=1;      
+            for (int i=0;i<3;i++)
+            {
+                printf("%f\t",data[i]); //printing the angular velocity values
+            }
+            printf("\n");
+            break;
+        }
+            drFlag=0;
+    }
+    ssn=0;
+    spi.write(PWR_MGMT_1|READFLAG); //sending address of PWR_MGMT_1 with readflag
+    response=spi.write(DUMMYBIT);
+    ssn=1;
+    wait(0.1);
+        
+    ssn=0;
+    spi.write(PWR_MGMT_1); //sending PWR_MGMT_1 address to write to register
+    response=spi.write(response|BIT_SLEEP); //setting the gyroscope in sleep mode
+    ssn=1;
+    wait(0.1);
+}