SYSCLK_Init ();                     // Initialize system clock to 
                                       // 12MHz
   PORT_Init ();                       // Initialize crossbar and GPIO
   Timer2_Init();                      // Init Timer2 to generate 
                                       // overflows to trigger ADC
   UART0_Init();                       // Initialize UART0 for printf's
   ADC0_Init();                        // Initialize ADC0

   EA = 1;							         // enable global interrupts
   while (1) {                         // spin forever
   ADC_Read_Ch(0x0C);
   }
}

//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------
//
//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
// 
// Return Value:  None
// Parameters:    None
//
// This routine initializes the system clock to use the internal 24.5MHz 
// oscillator as its clock source.  Also enables missing clock detector reset.
//
//-----------------------------------------------------------------------------

void SYSCLK_Init (void)
{
   OSCICN = 0x83;                      // configure internal oscillator for
                                       // 24.5MHz / 1
   RSTSRC = 0x04;                      // enable missing clock detector
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
// 
// Return Value:  None
// Parameters:    None
//
// Configure the Crossbar and GPIO ports.
// P0.0 - VREF input / output
// P0.4 - UART TX (push-pull)
// P0.5 - UART RX 
// P2.5 - ADC0 analog input
// P3.3 - LED (push-pull)
// 
//-----------------------------------------------------------------------------

void PORT_Init (void)
{
   XBR0     = 0x01;                    // Enable UART0
   XBR1     = 0x40;                    // Enable crossbar and weak pull-ups
   P0MDOUT |= 0x11;                    // Set P0.1, TX pins to push-pull
   P0SKIP   = 0x01;                    // force crossbar to skip P0.0
   P3MDOUT |= 0x08;                    // enable LED as a push-pull output
   P2MDIN &= ~0x20;                    // set P2.5 as an analog input
   P3MDIN = 0xFF;
   P0 = 0x01;                          // drive P0.0 high to provide Vdd at
                                       // header for external voltage divider
}

//-----------------------------------------------------------------------------
// Timer2_Init
//-----------------------------------------------------------------------------
// 
// Return Value:  None
// Parameters:    None
//
// Configure Timer2 to 16-bit auto-reload and generate an interrupt at 100uS 
// intervals.  Timer 2 overflow automatically triggers ADC0 conversion.
// 
//-----------------------------------------------------------------------------

void Timer2_Init (void)
{
   TMR2CN  = 0x00;                     // Stop Timer2; Clear TF2;
                                       // use SYSCLK as timebase, 16-bit 
                                       // auto-reload
   CKCON  |= 0x10;                     // select SYSCLK for timer 2 source
   TMR2RL  = 65535 - (SYSCLK / 10000); // init reload value for 10uS
   TMR2    = 0xffff;                   // set to reload immediately
   TR2     = 1;                        // start Timer2
}

//-----------------------------------------------------------------------------
// ADC0_Init
//-----------------------------------------------------------------------------
// 
// Return Value:  None
// Parameters:    None
//
// Configures ADC0 to make single-ended analog measurements on pin P2.5
//  
//-----------------------------------------------------------------------------
void ADC0_Init (void)
{
   ADC0CN = 0x02;                      // ADC0 disabled, normal tracking, 
                                       // conversion triggered on TMR2 overflow

   REF0CN = 0x0E;                      // Enable on-chip VREF, select Vdd as 
                                       // voltage reference. 

   AMX0P = 0x11;                       // ADC0 positive input = P2.5
   AMX0N = 0x1F;                       // ADC0 negative input = GND
                                       // i.e., single ended mode

   ADC0CF = ((SYSCLK/3000000)-1)<<3;   // set SAR clock to 3MHz

   ADC0CF |= 0x00;                     // right-justify results 

   EIE1 |= 0x08;                       // enable ADC0 conversion complete int.

   AD0EN = 1;                          // enable ADC0
}

//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
// 
// Return Value:  None
// Parameters:    None
//
// Configure the UART0 using Timer1, for <BAUDRATE> and 8-N-1.
//
//-----------------------------------------------------------------------------
void UART0_Init (void)
{
   SCON0 = 0x10;                       // SCON0: 8-bit variable bit rate
                                       //        level of STOP bit is ignored
                                       //        RX enabled
                                       //        ninth bits are zeros
                                       //        clear RI0 and TI0 bits
   if (SYSCLK/BAUDRATE/2/256 < 1) {
      TH1 = -(SYSCLK/BAUDRATE/2);
      CKCON |=  0x08;                  // T1M = 1; SCA1:0 = xx
   } else if (SYSCLK/BAUDRATE/2/256 < 4) {
      TH1 = -(SYSCLK/BAUDRATE/2/4);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 01
      CKCON |=  0x01;
   } else if (SYSCLK/BAUDRATE/2/256 < 12) {
      TH1 = -(SYSCLK/BAUDRATE/2/12);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 00
   } else if (SYSCLK/BAUDRATE/2/256 < 48) {
      TH1 = -(SYSCLK/BAUDRATE/2/48);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 10
      CKCON |=  0x02;
   } else {
      while (1);                       // Error.  Unsupported baud rate
   }

   TL1 = TH1;                          // init Timer1
   TMOD &= ~0xf0;                      // TMOD: timer 1 in 8-bit autoreload
   TMOD |=  0x20;
   TR1 = 1;                            // START Timer1
   TI0 = 1;                            // Indicate TX0 ready
}

//-----------------------------------------------------------------------------
// Interrupt Service Routines
//-----------------------------------------------------------------------------
//
//-----------------------------------------------------------------------------
// ADC0_ISR
//-----------------------------------------------------------------------------
// 
// Return Value:  None
// Parameters:    None
//
// This ISR averages 2048 samples then prints the result to the terminal.  The 
// ISR is called after each ADC conversion which is triggered by Timer2.
//
//-----------------------------------------------------------------------------
void ADC0_ISR (void) interrupt 10
{

   static unsigned long accumulator = 0;     // accumulator for averaging
   static unsigned int measurements = 2048;  // measurement counter
   unsigned long result=0;
   unsigned long mV;                   // measured voltage in mV

   AD0INT = 0;                         // clear ADC0 conversion complete flag

   accumulator += ADC0;
   measurements--;

   if(measurements == 0)
   {  
      measurements = 2048;
      result = accumulator / 2048;
      accumulator=0;

      // The 10-bit ADC value is averaged across 2048 measurements.  
      // The measured voltage applied to P1.4 is then:
      //
      //                           Vref (mV)
      //   measurement (mV) =   --------------- * result (bits) 
      //                       (2^10)-1 (bits)

      mV =  result * 3250 / 1023;   
      printf("P3.1 voltage: %ld mV\n",mV);
   }
   
   LED=~LED;
}

//-----------------------------------------------------------------------------
// End Of File
//-----------------------------------------------------------------------------