f06x_uart0_interrupt.c

// This program demonstrates how to configure the C8051F060 to write to and read // from the UART i

//-----------------------------------------------------------------------------
// F06x_UART0_Interrupt.c
//-----------------------------------------------------------------------------
// Copyright 2007 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program demonstrates how to configure the C8051F060 to write to and read
// from the UART interface. The program reads a word using the UART0 interrupts
// and outputs that word to the screen, with all characters in uppercase
//
// How To Test:
//
// 1) Download code to a 'F060 target board
// 2) Connect serial cable from the transceiver to a PC
// 3) On the PC, open HyperTerminal (or any other terminal program) and connect
//    to the COM port at <BAUDRATE> and 8-N-1
// 4) Type up to 64 characters into the Terminal and press Enter.  The MCU 
//    will then print back the characters that were typed
//
//
// Target:         C8051F06x
// Tool chain:     Keil C51 7.50 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0
//    -Initial Revision (SM)
//    -11 JULY 2007
//

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

#include <C8051F060.h>                 // SFR declarations
#include <stdio.h>

//-----------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F06x
//-----------------------------------------------------------------------------

sfr16 RCAP2    = 0xCA;                 // Timer2 capture/reload
sfr16 TMR2     = 0xCC;                 // Timer2

//-----------------------------------------------------------------------------
// Global Constants
//-----------------------------------------------------------------------------

#define BAUDRATE    9600            // Baud rate of UART in bps

// SYSTEMCLOCK = System clock frequency in Hz
#define SYSTEMCLOCK       24500000L

//-----------------------------------------------------------------------------
// Function Prototypes
//-----------------------------------------------------------------------------

void OSCILLATOR_Init (void);
void PORT_Init (void);
void UART0_Init (void);

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

#define UART_BUFFERSIZE 10
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)
{
   SFRPAGE = CONFIG_PAGE;

   WDTCN = 0xDE;                       // Disable watchdog timer
   WDTCN = 0xAD;

   OSCILLATOR_Init ();                 // Initialize oscillator
   PORT_Init ();                       // Initialize crossbar and GPIO

   UART0_Init ();                      // Initialize UART0

   EA = 1;

   SFRPAGE = UART0_PAGE;

   while (1)
   {
      // If the complete word has been entered via the terminal followed
      // by carriage return
     if((TX_Ready == 1) && (UART_Buffer_Size != 0) && (Byte == 67))
	 // if((TX_Ready == 1) && (UART_Buffer_Size != 0))
      {
         TX_Ready = 0;                  // Set the flag to zero
         TI0 = 1;                       // Set transmit flag to 1
      }
   }
}

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

//-----------------------------------------------------------------------------
// OSCILLATOR_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function initializes the system clock to use an external 22.1184MHz
// crystal.
//
//-----------------------------------------------------------------------------
void OSCILLATOR_Init (void)
{
   int i;                              // Software timer

   char SFRPAGE_SAVE = SFRPAGE;        // Save Current SFR page

   SFRPAGE = CONFIG_PAGE;              // Set SFR page

   OSCICN = 0x83;                      // Set internal oscillator to run
                                       // at its slowest frequency

   CLKSEL = 0x00;                      // Select the internal osc. as
                                       // the SYSTEMCLOCK source

   // Initialize external crystal oscillator to use 22.1184 MHz crystal

   OSCXCN = 0x67;                      // Enable external crystal osc.
   for (i=0; i < 256; i++);            // Wait at least 1ms

   while (!(OSCXCN & 0x80));           // Wait for crystal osc to settle

   CLKSEL = 0x00;
   // Select external crystal as SYSTEMCLOCK source

   SFRPAGE = SFRPAGE_SAVE;             // Restore SFRPAGE
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function configures the crossbar and GPIO ports.
//
// Pinout:
//
// P0.0   digital   push-pull     UART TX
// P0.1   digital   open-drain    UART RX
// P1.6   digital   push-pull     LED
//-----------------------------------------------------------------------------
void PORT_Init (void)
{
   char SFRPAGE_SAVE = SFRPAGE;        // Save Current SFR page

   SFRPAGE = CONFIG_PAGE;              // Set SFR page

   XBR0     = 0x04;                    // Enable UART0
   XBR1     = 0x00;
   XBR2     = 0x40;                    // Enable crossbar and weak pull-up


   P0MDOUT |= 0x01;                    // Set TX pin to push-pull
   P1MDOUT |= 0x40;                    // Set P1.6(LED) to push-pull

   SFRPAGE = SFRPAGE_SAVE;             // Restore SFR page
}

//-----------------------------------------------------------------------------
// UART0_Init   Variable baud rate, Timer 2, 8-N-1
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Configure UART0 for operation at <BAUDRATE> 8-N-1 using Timer2 as
// baud rate source.
//
//-----------------------------------------------------------------------------
void UART0_Init (void)
{
   char SFRPAGE_SAVE;

   SFRPAGE_SAVE = SFRPAGE;             // Preserve SFRPAGE

   SFRPAGE = TMR2_PAGE;

   TMR2CN = 0x00;                      // Timer in 16-bit auto-reload up timer
                                       // mode
   TMR2CF = 0x08;                      // SYSCLK is time base; no output;
                                       // up count only
   RCAP2 = - ((long) SYSTEMCLOCK/BAUDRATE/16);
   TMR2 = RCAP2;
   TR2= 1;                             // Start Timer2

   SFRPAGE = UART0_PAGE;

   SCON0 = 0x50;                       // 8-bit variable baud rate;
                                       // 9th bit ignored; RX enabled
                                       // clear all flags
   SSTA0 = 0x15;                       // Clear all flags; enable baud rate
                                       // doubler (not relevant for these
                                       // timers);
                                       // Use Timer2 as RX and TX baud rate
                                       // source;
   ES0 = 1;
   IP |= 0x10;

   SFRPAGE = SFRPAGE_SAVE;             // Restore SFRPAGE
}

//-----------------------------------------------------------------------------
// 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
{
   SFRPAGE = UART0_PAGE;

   if (RI0 == 1)
   {
     // Check if a new word is being entered
     if( UART_Buffer_Size == 0) {
        UART_Input_First = 0; }

     RI0 = 0;
     Byte = SBUF0;   // Read a character from Hyperterminal
     
     if (UART_Buffer_Size < UART_BUFFERSIZE)
     {
        UART_Buffer[UART_Input_First] = Byte;

        UART_Buffer_Size++;            // Update array's size

        UART_Input_First++;            // Update counter
     }
   }

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

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

         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;                  // Transmission complete
      }
   }
}

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