f500_uart0_stdio.c

C8051F500开发编程：MCU全部资源应用实例

//-----------------------------------------------------------------------------
// F500_UART0_STDIO.c
//-----------------------------------------------------------------------------
// Copyright 2008 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program demonstrates how to configure the C8051F500 to use routines
// in STDIO.h to write to and read from the UART interface.  The program
// reads a character using the STDIO routine getkey(), outputs that character
// to the screen, and then outputs the ASCII hex value of that character.
//
//
// How To Test:
//
// 1) Ensure that jumpers are placed on J17 of the C8051F500 target board
//    that connect P0.4 to the TX signal, and P0.5 to the RX field.
// 2) Connect USB cable from the development board to a PC
// 3) Specify the target baudrate in the constant <BAUDRATE>.
// 4) On the PC, open HyperTerminal (or any other terminal program) and connect
//    to the USB port (virtual com port) at <BAUDRATE>, 8 data bits, no parity,
//    1 stop bit and no flow control.
// 5) Download and execute code to an 'F500 target board.
//
//
// Target:         C8051F500 (Side A of a C8051F500-TB)
// Tool chain:     Keil C51 8.0 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0 / 10 MAR 2008 (GP)
//    -Initial Revision
//

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

#include <compiler_defs.h>
#include <C8051F500_defs.h>            // SFR declarations
#include <stdio.h>

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

#define SYSCLK      24000000           // SYSCLK frequency in Hz
#define BAUDRATE      115200           // Baud rate of UART in bps

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

void SYSCLK_Init (void);
void UART0_Init (void);
void PORT_Init (void);

#ifdef SDCC
 U8 getkey (void);
 void putchar (char output);
#endif

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

void main (void)
{
   U8 inputcharacter;                  // Used to store character from UART

   SFRPAGE = ACTIVE_PAGE;              // Change for PCA0MD and SBUF0
   PCA0MD &= ~0x40;                    // Disable the watchdog timer

   PORT_Init ();                       // Initialize Port I/O
   SYSCLK_Init ();                     // Initialize Oscillator
   UART0_Init ();

   while (1)
   {
      printf ("\nEnter character: ");
      inputcharacter = getkey ();
      printf ("\nCharacter entered : %c",inputcharacter);
      printf ("\n      Value in Hex: %bx",inputcharacter);
   }
}

//-----------------------------------------------------------------------------
// 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)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = CONFIG_PAGE;

   P0MDOUT |= 0x10;                    // Enable UTX as push-pull output
   XBR0    = 0x01;                     // Enable UART on P0.4(TX) and P0.5(RX)
   XBR2    = 0x40;                     // Enable crossbar and weak pull-ups

   SFRPAGE = SFRPAGE_save;
}

//-----------------------------------------------------------------------------
// 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)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = CONFIG_PAGE;

   OSCICN |= 0x87;                     // Configure internal oscillator for
                                       // its maximum frequency
   RSTSRC  = 0x04;                     // Enable missing clock detector

   SFRPAGE = SFRPAGE_save;
}

//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Configure the UART0 using Timer1, for <BAUDRATE> and 8-N-1.
//-----------------------------------------------------------------------------
void UART0_Init (void)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = CONFIG_PAGE;

   SCON0 = 0x10;                       // SCON0: 8-bit variable bit rate
                                       // clear RI0 and TI0 bits

   // Baud Rate = [BRG Clock / (65536 - (SBRLH0:SBRLL0))] x 1/2 x 1/Prescaler

#if   ((SYSCLK / BAUDRATE / 2 / 0xFFFF) < 1)
      SBRL0 = -(SYSCLK / BAUDRATE / 2);
      SBCON0 |= 0x03;                  // Set prescaler to 1
#elif ((SYSCLK / BAUDRATE / 2 / 0xFFFF) < 4)
      SBRL0 = -(SYSCLK / BAUDRATE / 2 / 4);
      SBCON0 &= ~0x03;
      SBCON0 |= 0x01;                  // Set prescaler to 4
#elif ((SYSCLK / BAUDRATE / 2 / 0xFFFF) < 12)
      SBRL0 = -(SYSCLK / BAUDRATE / 2 / 12);
      SBCON0 &= ~0x03;                 // Set prescaler to 12
#else
      SBRL0 = -(SYSCLK / BAUDRATE / 2 / 48);
      SBCON0 &= ~0x03;
      SBCON0 |= 0x02;                  // Set prescaler to 48
#endif

   SBCON0 |= 0x40;                     // Enable baud rate generator
   TI0 = 1;                            // Indicate TX0 ready

   SFRPAGE = SFRPAGE_save;
}

#ifdef SDCC

// SDCC does not include a definition for putchar(), which is used in printf()
// and so it is defined here.  The prototype does not need to be explicitly
// defined because it is provided in stdio.h

//-----------------------------------------------------------------------------
// putchar
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : character to send to UART
//
// This function outputs a character to the UART.
//-----------------------------------------------------------------------------
void putchar (char output)
{
   if (output == '\n')
   {
      while (!TI0);
      TI0 = 0;
      SBUF0 = 0x0D;
   }
   while (!TI0);
   TI0 = 0;
   SBUF0 = output;
}

// SDCC does not include a definition for getkey(), and so it is defined here

//-----------------------------------------------------------------------------
// getkey
//-----------------------------------------------------------------------------
//
// Return Value : character received from UART
// Parameters   : None
//
// This function returns a character received from the UART
// Assumes SFR page has been set correctly by the application
//-----------------------------------------------------------------------------
U8 getkey (void)
{
   U8 received;

   while (!RI0);                       // Wait for character to be received
   received = SBUF0;                   // Read it
   RI0 = 0;                            // Clear received data indicator

   return received;
}

#endif

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