I2CcommFunctions.h

00001 #define I2Cmode                                     //Used to check if the sensor is in I2C mode or SPI mode.
00002 #define I2C_Slave_ID 0x57                           //Slave ID is 0x57 only if p22 and p23 are both HIGH.
00003 
00004 //=========================================================================
00005 //Communication pinouts for serial COM port, I2C, and interrupts
00006 //=========================================================================
00007 static Serial pc(USBTX, USBRX);                     //PC comm
00008 static I2C i2c(p26, p27);                           //SDA, SCL
00009 static DigitalOut cs(p22);                          //CS pin for selecting slave address
00010 static DigitalOut MOSI(p23);                        //MOSI pin for selecting slave address
00011 static DigitalOut shutdown(p20);                    //Shutdown pin
00012 static DigitalOut IO_sel(p19);                      //IO interface selection pin (I2C and SPI)
00013 
00014 
00015 //=========================================================================
00016 //Variables and arrays used for communications and data storage
00017 //=========================================================================
00018 int8_t deltaX, deltaY;                              //Stores the value of one individual motion report.
00019 int totalX, totalY = 0;                          //Stores the total deltaX and deltaY moved during runtime.
00020 
00021 
00022 //=========================================================================
00023 //Functions used to communicate with the sensor and grab/print data
00024 //=========================================================================
00025 uint8_t readRegister(uint8_t addr);
00026 //This function takes an 8-bit address in the form 0x00 and returns an 8-bit value in the form 0x00.
00027 
00028 void writeRegister(uint8_t addr, uint8_t data);
00029 //This function takes an 8-bit address and 8-bit data. Writes the given data to the given address.
00030 
00031 void load(const uint8_t array[][2], uint8_t arraySize);
00032 //Takes an array of registers/data (found in registerArrays.h) and their size and writes in all the values.
00033 
00034 void grabData(void);
00035 //Grabs the deltaX and deltaY information from the proper registers and formats it into the proper format.
00036 
00037 void printData(void);
00038 //Prints the data out to a serial terminal.
00039 
00040 
00041 
00042 
00043 
00044 //=========================================================================
00045 //Functions definitions
00046 //=========================================================================
00047 uint8_t readRegister(uint8_t addr)
00048 {
00049     uint8_t data;
00050     i2c.write((I2C_Slave_ID << 1), (const char*)&addr, 1, 0);   //Send the address to the chip
00051     i2c.read((I2C_Slave_ID << 1), (char*)&data, 1, 0);          //Send the memory address where you want to store the read data
00052     return(data);
00053 }
00054 
00055 
00056 //=========================================================================
00057 void writeRegister(uint8_t addr, uint8_t data)
00058 {
00059     char data_write[2];             //Create an array to store the address/data to pass them at the same time.
00060     data_write[0] = addr;           //Store the address in the first byte
00061     data_write[1] = data;           //Store the data in the second byte
00062     i2c.write((I2C_Slave_ID << 1), data_write, 2, 0);   //Send both over at once
00063     
00064     pc.printf("R:%2X, D:%2X\n\r", addr, readRegister(addr));
00065             //Uncomment this line for debugging. Prints every register write operation.
00066 }
00067 
00068 
00069 //=========================================================================
00070 void load(const uint8_t array[][2], uint8_t arraySize)
00071 {
00072     for(uint8_t q = 0; q < arraySize; q++)
00073     {
00074         writeRegister(array[q][0], array[q][1]);    //Writes the given array of registers/data.
00075     }
00076 }
00077 
00078 
00079 //=========================================================================
00080 void grabData(void)
00081 {
00082     deltaX = readRegister(0x03);        //Grabs data from the proper registers.
00083     deltaY = readRegister(0x04);
00084     writeRegister(0x02, 0x00);          //Clear EVENT and motion registers.
00085 }
00086 
00087 
00088 //=========================================================================
00089 void printData(void)
00090 {
00091     if((deltaX != 0) || (deltaY != 0))      //If there is deltaX or deltaY movement, print the data.
00092     {
00093         totalX += deltaX;
00094         totalY += deltaY;
00095         
00096         pc.printf("deltaX: %d\t\t\tdeltaY: %d\n\r", deltaX, deltaY);    //Prints each individual count of deltaX and deltaY.
00097         pc.printf("X-axis Counts: %d\t\tY-axis Counts: %d\n\r", totalX, totalY);  //Prints the total movement made during runtime.
00098     }
00099     
00100     deltaX = 0;                             //Resets deltaX and Y values to zero, otherwise previous data is stored until overwritten.
00101     deltaY = 0;
00102 }