f500_smbus_slave.c

C8051F500开发编程：MCU全部资源应用实例

//-----------------------------------------------------------------------------
// F500_SMBus_Slave.c
//-----------------------------------------------------------------------------
// Copyright 2008 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// Example software to demonstrate the C8051F500 SMBus interface in Slave mode
// - Interrupt-driven SMBus implementation
// - Only slave states defined
// - 1-byte SMBus data holder used for both transmit and receive
// - Timer1 used as SMBus clock rate (used only for free timeout detection)
// - Timer3 used by SMBus for SCL low timeout detection
// - ARBLOST support included
// - Pinout:
//    P0.0 -> SDA (SMBus)
//    P0.1 -> SCL (SMBus)
//    P1.3 -> LED
//
// How To Test:
//
// 1) Verify that J22 is not populated.
// 2) Download code to a 'F500 device that is connected to a SMBus master.
// 3) Run the code.  The slave code will write data and read data from the
//    same data byte, so a successive write and read will effectively echo the
//    data written.  To verify that the code is working properly, verify on the
//    master that the data written is the same as the data received.
//
// Target:         C8051F500 (Side A of a C8051F500-TB)
// Tool chain:     Keil C51 8.0 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0 / 05 MAR 2008 (GP)
//    -Initial Revision
//

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

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

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

#define  SYSCLK         24000000       // System clock frequency in Hz

#define  SMB_FREQUENCY  10000          // Target SMBus frequency
                                       // This example supports between 10kHz
                                       // and 100kHz

#define  WRITE          0x00           // SMBus WRITE command
#define  READ           0x01           // SMBus READ command

#define  SLAVE_ADDR     0xF0           // Device addresses (7 bits,
                                       // lsb is a don't care)

// Status vector - top 4 bits only
#define  SMB_SRADD      0x20           // (SR) slave address received
                                       //    (also could be a lost
                                       //    arbitration)
#define  SMB_SRSTO      0x10           // (SR) STOP detected while SR or ST,
                                       //    or lost arbitration
#define  SMB_SRDB       0x00           // (SR) data byte received, or
                                       //    lost arbitration
#define  SMB_STDB       0x40           // (ST) data byte transmitted
#define  SMB_STSTO      0x50           // (ST) STOP detected during a
                                       //    transaction; bus error
// End status vector definition

//-----------------------------------------------------------------------------
// Global VARIABLES
//-----------------------------------------------------------------------------

U8 SMB_DATA;                           // Global holder for SMBus data.
                                       // All receive data is written
                                       // here;
                                       // all transmit data is read
                                       // from here

bit DATA_READY = 0;                    // Set to '1' by the SMBus ISR
                                       // when a new data byte has been
                                       // received.

SBIT (LED, SFR_P1, 3);                 // LED==1 means ON

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

void SMBUS0_Init (void);
void TIMER1_Init (void);
void TIMER3_Init (void);
void PORT_Init (void);

INTERRUPT_PROTO (TIMER3_ISR, INTERRUPT_TIMER3);
INTERRUPT_PROTO (SMBUS0_ISR, INTERRUPT_SMBUS0);

//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------
//
// Main routine performs all configuration tasks, then waits for SMBus
// communication.
//
//-----------------------------------------------------------------------------
void main (void)
{
   SFRPAGE = ACTIVE_PAGE;              // Set SFR Page for PCA0

   PCA0MD = 0x00;                      // Disable watchdog timer

   SFRPAGE = CONFIG_PAGE;              // Set SFR Page for XBR and port pins

   OSCICN |= 0x07;                     // Set internal oscillator to 24 MHz

   PORT_Init();                        // Initialize Crossbar and GPIO
   TIMER1_Init();                      // Configure Timer1 for use
                                       // with SMBus baud rate

   TIMER3_Init();                      // Configure Timer3 for use with
                                       // SCL low timeout detect

   SMBUS0_Init ();                      // Configure and enable SMBus

   EIE1 |= 0x01;                       // Enable the SMBus interrupt

   LED = 0;

   EA = 1;                             // Global interrupt enable

   SMB_DATA = 0xFD;                    // Initialize SMBus data holder

   while(1)
   {
      while(!DATA_READY);              // New SMBus data received?
      DATA_READY = 0;
      LED = !LED;
   }
}

//-----------------------------------------------------------------------------
// Initialization Routines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// SMBUS0_Init()
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// SMBus configured as follows:
// - SMBus enabled
// - Slave mode not inhibited
// - Timer1 used as clock source. The maximum SCL frequency will be
//   approximately 1/3 the Timer1 overflow rate
// - Setup and hold time extensions enabled
// - Bus Free and SCL Low timeout detection enabled
//
//-----------------------------------------------------------------------------
void SMBUS0_Init (void)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = ACTIVE_PAGE;

   SMB0CF = 0x1D;                      // Use Timer1 overflows as SMBus clock
                                       // source;
                                       // Enable slave mode;
                                       // Enable setup & hold time
                                       // extensions;
                                       // Enable SMBus Free timeout detect;
                                       // Enable SCL low timeout detect;

   SMB0CF |= 0x80;                     // Enable SMBus;

   SFRPAGE = SFRPAGE_save;
}

//-----------------------------------------------------------------------------
// TIMER1_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Timer1 configured as the SMBus clock source as follows:
// - Timer1 in 8-bit auto-reload mode
// - SYSCLK or SYSCLK / 4 as Timer1 clock source
// - Timer1 overflow rate => 3 * SMB_FREQUENCY
// - The resulting SCL clock rate will be ~1/3 the Timer1 overflow rate
// - Timer1 enabled
//
//-----------------------------------------------------------------------------
void TIMER1_Init (void)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = ACTIVE_PAGE;

// Make sure the Timer can produce the appropriate frequency in 8-bit mode
// Supported SMBus Frequencies range from 10kHz to 100kHz.  The CKCON register
// settings may need to change for frequencies outside this range.
#if ((SYSCLK/SMB_FREQUENCY/3) < 255)