//-----------------------------------------------------------------------------
// F31x_UART0_Interrupt.c
//-----------------------------------------------------------------------------
// Copyright 2007 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program demonstrates how to configure the C8051F310 to write to and read
// from the UART interface. The program reads a word using the UART interrupts
// and outputs that word to the screen, with all characters in uppercase
//
// How To Test:
//
// 1) Ensure that jumpers are placed on J3 of the C8051F310 target board
//    that connect the P0.4 pin to the TX signal, and P0.5 to the RX signal.
// 2) Ensure that the serial cable is connected to the RS232 connector
//    on the target board.
// 3) Specify the target baudrate in the constant <BAUDRATE>.
// 4) Open Hyperterminal, or a similar program, and connect to the target
//    board's serial port.
// 5) Download and execute code on an 'F31x target board.
// 6) Type up to 64 characters into the Terminal and press Enter.  The MCU 
//    will then print back the characters that were typed
//
// Target:         C8051F31x
// Tool chain:     Keil C51 7.50 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0
//    -Initial Revision (SM)
//    -5 JUN 2007
//
//

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <c8051f310.h>                 // SFR declarations
#include <stdio.h>

//-----------------------------------------------------------------------------
// Global CONSTANTS
//-----------------------------------------------------------------------------

#define SYSCLK      24500000           // SYSCLK frequency in Hz
#define BAUDRATE        9600           // Baud rate of UART in bps


//-----------------------------------------------------------------------------
// Function PROTOTYPES
//-----------------------------------------------------------------------------

void SYSCLK_Init (void);
void UART0_Init (void);
void PORT_Init (void);
void Timer2_Init (int);

//-----------------------------------------------------------------------------
// Global Variables
//-----------------------------------------------------------------------------

#define UART_BUFFERSIZE 64
unsigned char UART_Buffer[UART_BUFFERSIZE];
unsigned char UART_Buffer_Size = 0;
unsigned char UART_Input_First = 0;
unsigned char UART_Output_First = 0;
unsigned char TX_Ready =1;
static char Byte;

//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------

void main (void)
{
   PCA0MD &= ~0x40;                    // WDTE = 0 (clear watchdog timer
                                       // enable)
   PORT_Init();                        // Initialize Port I/O
   SYSCLK_Init ();                     // Initialize Oscillator
   UART0_Init();

   EA = 1;

   while(1)
   {
      // If the complete word has been entered via the hyperterminal followed by
      // carriage return
      if((TX_Ready == 1) && (UART_Buffer_Size != 0) && (Byte == 13))
      {
         TX_Ready = 0;                 // Set the flag to zero
         TI0 = 1;                      // Set transmit flag to 1
      }
   }
}

//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Configure the Crossbar and GPIO ports.
//
// P0.4   digital   push-pull    UART TX
// P0.5   digital   open-drain   UART RX
//
//-----------------------------------------------------------------------------
void PORT_Init (void)
{
   P0MDOUT |= 0x10;                    // Enable UTX as push-pull output
   XBR0    = 0x01;                     // Enable UART on P0.4(TX) and P0.5(RX)
   XBR1    = 0x40;                     // Enable crossbar and weak pull-ups
}

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This routine initializes the system clock to use the internal oscillator
// at its maximum frequency.
// Also enables the Missing Clock Detector.
//-----------------------------------------------------------------------------

void SYSCLK_Init (void)
{
   OSCICN |= 0x03;                     // Configure internal oscillator for
                                       // its maximum frequency
   RSTSRC  = 0x04;                     // Enable missing clock detector
}

//-----------------------------------------------------------------------------
// 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 &= ~0x0B;                  // T1M = 1; SCA1:0 = xx
      CKCON |=  0x08;
   } 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 {
      TH1 = -(SYSCLK/BAUDRATE/2/48);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 10
      CKCON |=  0x02;
   }

   TL1 = TH1;                          // init Timer1
   TMOD &= ~0xf0;                      // TMOD: timer 1 in 8-bit autoreload
   TMOD |=  0x20;
   TR1 = 1;                            // START Timer1
   TX_Ready = 1;                       // Flag showing that UART can transmit
   IP |= 0x10;                         // Make UART high priority
   ES0 = 1;                            // Enable UART0 interrupts
}

//-----------------------------------------------------------------------------
// Interrupt Service Routines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// UART0_Interrupt
//-----------------------------------------------------------------------------
//
// This routine is invoked whenever a character is entered or displayed on the
// Hyperterminal.
//
//-----------------------------------------------------------------------------

void UART0_Interrupt (void) interrupt 4
{
   if (RI0 == 1)
   {
      if( UART_Buffer_Size == 0)  {      // If new word is entered
         UART_Input_First = 0;    }

      RI0 = 0;                           // Clear interrupt flag

      Byte = SBUF0;                      // Read a character from UART

      if (UART_Buffer_Size < UART_BUFFERSIZE)
      {
         UART_Buffer[UART_Input_First] = Byte; // Store in array

         UART_Buffer_Size++;             // Update array's size

         UART_Input_First++;             // Update counter
      }
   }


   if (TI0 == 1)                   // Check if transmit flag is set
   {
      TI0 = 0;                           // Clear interrupt flag

      if (UART_Buffer_Size != 1)         // If buffer not empty
      {
         // If a new word is being output
         if ( UART_Buffer_Size == UART_Input_First ) {
              UART_Output_First = 0;  }

         // Store a character in the variable byte
         Byte = UART_Buffer[UART_Output_First];

         if ((Byte >= 0x61) && (Byte <= 0x7A)) { // If upper case letter
            Byte -= 32; }

         SBUF0 = Byte;                   // Transmit to Hyperterminal

         UART_Output_First++;            // Update counter

         UART_Buffer_Size--;             // Decrease array size

      }
      else
      {
         UART_Buffer_Size = 0;            // Set the array size to 0
         TX_Ready = 1;                    // Indicate transmission complete
      }
   }
}
//-----------------------------------------------------------------------------
// End Of File
//-----------------------------------------------------------------------------