Lynxmotion Tech Support

//**********************************************************

//Define pins
//PD0 and PD1 are reserved for USART
#define PS2_DATA   PA0   //data
#define PS2_CMD   PA1   //command
#define PS2_ATT   PA2   //attention
#define PS2_CLK   PA3   //clock

//Define constants for PS2 communication
#define PS2_START_CMD      0x01
#define PS2_REQUEST_DATA   0x42
#define PS2_CONFIG_MODE      0x43
#define PS2_CONFIG_MODE2   0x01
#define PS2_CONFIG_ANALOG   0x44
#define PS2_CONFIG_EXIT      0x00
#define PS2_SET_ANALOG      0x01
#define PS2_LOCK_ANALOG      0x03
#define PS2_DIGITAL_MODE   0x41
#define PS2_ANALOG_MODE      0x73
#define PS2_NO_CMD      0x00
//Define the locations of the different buttons in the data bytes

//Data byte 1 (PS2CMD1)
#define PS2_SELECT   0
#define PS2_L3      1
#define PS2_R3      2
#define PS2_START      3
#define PS2_UP      4
#define PS2_RIGHT      5
#define PS2_DOWN      6
#define PS2_LEFT      7
//Data byte 2 (PS2CMD2)
#define PS2_L2      0
#define PS2_R2      1
#define PS2_L1      2
#define PS2_R1      3
#define PS2_TRIANGLE   4
#define PS2_CIRCLE   5
#define PS2_X      6
#define PS2_SQUARE   7

//function prototypes
void PS2Init(void);
void PS2Get(void);
static unsigned char PS2ReadSend(unsigned char command);

//variables
   unsigned char PS2TEMP = 0x00;
   unsigned char PS2ID   = 0xFF;
   unsigned char PS2CMD1 = 0x00;
   unsigned char PS2CMD2 = 0x00;
   int RightHorizontal = 0x00;
   int RightVertical = 0x00;
   int LeftHorizontal = 0x00;
   int LeftVertical = 0x00;


//Function definitions


//*********************************************************************
//BEGIN PS2Init()   
//Purpose: Initializes the pins for PS2 communication and sets the
//controller into analog mode and locks it   
//Input: NONE
//Output: NONE
//*********************************************************************

void PS2Init(void)
{
   DDRA  |= (1<<PS2_CLK)|(1<<PS2_ATT)|(1<<PS2_CMD);
//set pins as outputs
   PORTA |= (1<<PS2_CLK)|(1<<PS2_ATT)|(1<<PS2_DATA);   
//start clock, attention high, pull up resistor on DATA

while(PS2ID == 0xFF)   //loop until controller present
{
   PORTA &= ~(1<<PS2_ATT);   //pull attention low
   PS2TEMP =    PS2ReadSend(PS2_START_CMD);
   PS2ID   =    PS2ReadSend(PS2_NO_CMD); //check for controller ID
   PORTA |= (1<<PS2_CLK);          //clock high
   PORTA |= (1<<PS2_ATT);          //attention high
}

//go into command mode
   PORTA &= ~(1<<PS2_ATT);         //pull attention low
   PS2TEMP =    PS2ReadSend(PS2_START_CMD);
   PS2TEMP =    PS2ReadSend(PS2_CONFIG_MODE);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PS2TEMP =    PS2ReadSend(PS2_CONFIG_MODE2);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PORTA |= (1<<PS2_CLK);         //clock high
   PORTA |= (1<<PS2_ATT);         //attention high


//set controller to analog mode and lock
   PORTA &= ~(1<<PS2_ATT);         //pull attention low
   PS2TEMP =    PS2ReadSend(PS2_START_CMD);
   PS2TEMP =    PS2ReadSend(PS2_CONFIG_ANALOG);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PS2TEMP =    PS2ReadSend(PS2_SET_ANALOG);
   PS2TEMP =    PS2ReadSend(PS2_LOCK_ANALOG);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PORTA |= (1<<PS2_CLK);         //clock high
   PORTA |= (1<<PS2_ATT);         //attention high


//exit configuration mode
   PORTA &= ~(1<<PS2_ATT);         //pull attention low
   PS2TEMP =    PS2ReadSend(PS2_START_CMD);
   PS2TEMP =    PS2ReadSend(PS2_CONFIG_MODE);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);
   PS2TEMP =    PS2ReadSend(PS2_NO_CMD);      
   PS2TEMP =    PS2ReadSend(0x5A);   
   PS2TEMP =    PS2ReadSend(0x5A);
   PS2TEMP =    PS2ReadSend(0x5A);
   PS2TEMP =    PS2ReadSend(0x5A);
   PS2TEMP =    PS2ReadSend(0x5A);
   PORTA |= (1<<PS2_CLK);         //clock high
   PORTA |= (1<<PS2_ATT);         //attention high

} // END PS2Init()
//*********************************************************************
//BEGIN PS2Get()
//Purpose: Gets the PS2 controller configuration. Returns (as a global
//variable) the joystick positions as a value from -255 to +255
//Input: NONE
//Output: NONE
//*********************************************************************
void PS2Get(void)
{
   PORTA &= ~(1<<PS2_ATT);            //pull attention low
   PS2TEMP =    PS2ReadSend(PS2_START_CMD);
   PS2ID   =    PS2ReadSend(PS2_REQUEST_DATA);
   PS2TEMP =   PS2ReadSend(PS2_NO_CMD);
   PS2CMD1 =    ~PS2ReadSend(PS2_NO_CMD);   //invert output so high
//means button pressed
   PS2CMD2 =    ~PS2ReadSend(PS2_NO_CMD);   //invert output so high
//means button pressed
   RightHorizontal =    PS2ReadSend(PS2_NO_CMD);
   RightVertical    =    PS2ReadSend(PS2_NO_CMD);
   LeftHorizontal  =    PS2ReadSend(PS2_NO_CMD);
   LeftVertical   =    PS2ReadSend(PS2_NO_CMD);
   PORTA |= (1<<PS2_CLK);            //clock high
   PORTA |= (1<<PS2_ATT);            //attention high

} //END PS2Get()

//*********************************************************************
//BEGIN PS2ReadSend()
//Purpose: The bitwise send command and read data function. This
//function is only to be called by the functions PS2Init() and PS2Get()
//and should never be called directly from the DRA code
//Input: PS2 commands
//Output: PS2 data
//*********************************************************************
unsigned char PS2ReadSend(unsigned char command)
//clock must be high before calling
{
   unsigned char PS2Data = 0x00;
   for(int i=0;i<8;i++)
   {
      PORTA &= ~(1<<PS2_CLK);      //set clock low      
      if(bit_is_set(command, i))   //is PS2 command bit i set?
         PORTA |= (1<<PS2_CMD);   //if yes set PS2_CMD bit
      else   
         PORTA &= ~(1<<PS2_CMD);   //if no clear PS2_CMD bit
      _delay_us(60);   //wait for PS2 controller to set data bit
      PORTA |= (1<<PS2_CLK);   //set clock high. Controller sets
                  //and reads on clock change
      if(bit_is_set(PINA, PS2_DATA)) //is PS2_DATA bit set?
         PS2Data |= (1<<i);   //if yes set PS2Data bit i
      else
         PS2Data &= ~(1<<i);   //if no clear PS2Data bit i
      _delay_us(60);                     //wait for PS2 controller to
   }
   _delay_us(300);   //wait for PS2 controller to acknowledge
   return PS2Data;
} // END PS2ReadSend()

//*********************************************************************