smbus_master.c

C51源码.其内文件包含spi

//-----------------------------------------------------------------------------
// F04x_SMBus_Master.c
//-----------------------------------------------------------------------------
// Copyright 2006 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// Example software to demonstrate the C8051F04x SMBus interface in
// Master mode.
// - Interrupt-driven SMBus implementation
// - Only master states defined (no slave or arbitration)
// - 1-byte SMBus data holders used for each transmit and receive
// - Timer4 used by SMBus for SCL low timeout detection
// - SCL frequency defined by <SMB_FREQUENCY> constant
// - ARBLOST support included
// - Pinout:
//    P0.0 -> SDA (SMBus)
//    P0.1 -> SCL (SMBus)
//
//    P1.6 -> LED
//
//    all other port pins unused
//
// How To Test:
//
// 1) Download code to a 'F04x device that is connected to a SMBus slave.
// 2) Run the code:
//         a) The test will indicate proper communication with the slave by
//            toggling the LED on and off each time a value is sent and
//            received.
//         b) The best method to view the proper functionality is to run to
//            the indicated line of code in the TEST CODE section of main and
//            view the SMB_DATA_IN and SMB_DATA_OUT variables in the Watch
//            Window.
//
//
// FID:            04X000008
// Target:         C8051F04x
// Tool chain:     Keil C51 7.50 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0
//    -Initial Revision (TP)
//    -20 APR 2006
//

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

#include <C8051F040.h>                 // SFR declarations

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

#define  SYSCLK         22118400L       // System clock frequency in Hz

#define  SMB_FREQUENCY  10000L         // Target SCL clock rate
                                       // This example supports between 10kHz
                                       // and 100kHz

#define  WRITE          0x00           // WRITE direction bit
#define  READ           0x01           // READ direction bit

// Device addresses (7 bits, lsb is a don't care)
#define  SLAVE_ADDR     0xD0           // Device address for slave target

#define  MY_ADDR        0x02           // Address of this SMBus device
                                       // (dummy value since this device does
                                       // not have any defined slave states)

#define  SMB_BUS_ERROR  0x00           // (all modes) BUS ERROR

#define  SMB_START      0x08           // (MT & MR) START transmitted
#define  SMB_RP_START   0x10           // (MT & MR) repeated START
#define  SMB_MTADDACK   0x18           // (MT) Slave address + W transmitted;
                                       //    ACK received
#define  SMB_MTADDNACK  0x20           // (MT) Slave address + W transmitted;
                                       //    NACK received
#define  SMB_MTDBACK    0x28           // (MT) data byte transmitted;
                                       //    ACK rec'vd
#define  SMB_MTDBNACK   0x30           // (MT) data byte transmitted;
                                       //    NACK rec'vd
#define  SMB_MTARBLOST  0x38           // (MT) arbitration lost
#define  SMB_MRADDACK   0x40           // (MR) Slave address + R transmitted;
                                       //    ACK received
#define  SMB_MRADDNACK  0x48           // (MR) Slave address + R transmitted;
                                       //    NACK received
#define  SMB_MRDBACK    0x50           // (MR) data byte rec'vd;
                                       //    ACK transmitted
#define  SMB_MRDBNACK   0x58           // (MR) data byte rec'vd;
                                       //    NACK transmitted

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

unsigned char SMB_DATA_IN;             // Global holder for SMBus data
                                       // All receive data is written here

unsigned char SMB_DATA_OUT;            // Global holder for SMBus data.
                                       // All transmit data is read from here

unsigned char TARGET;                  // Target SMBus slave address

bit SMB_BUSY;                          // Software flag to indicate when the
                                       // SMB_Read() or SMB_Write() functions
                                       // have claimed the SMBus

bit SMB_RW;                            // Software flag to indicate the
                                       // direction of the current transfer

unsigned long NUM_ERRORS;              // Counter for the number of errors.

// 16-bit SFR declarations
sfr16    RCAP4    = 0xCA;              // Timer4 reload registers
sfr16    TMR4     = 0xCC;              // Timer4 counter registers

sbit SDA = P0^6;                       // SMBus on P0.0
sbit SCL = P0^7;                       // and P0.1

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

void SYSCLK_Init(void);
void Port_Init(void);
void SMBus_Init(void);
void Timer4_Init(void);

void SMBus_ISR(void);
void Timer4_ISR(void);

void SMB_Write (void);
void SMB_Read (void);
void T0_Wait_ms (unsigned char ms);

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

void MAIN (void)
{
   volatile unsigned char dat;         // Test counter
   unsigned char i;                    // Dummy variable counters

   WDTCN = 0xde;                       // Disable watchdog timer
   WDTCN = 0xad;

   SYSCLK_Init ();                     // Set internal oscillator to a setting
                                       // of 3062500 Hz

   // If slave is holding SDA low because of an improper SMBus reset or error
   while(!SDA)
   {
      // Provide clock pulses to allow the slave to advance out
      // of its current state. This will allow it to release SDA.
      XBR1 = 0x40;                     // Enable Crossbar
      SCL = 0;                         // Drive the clock low
      for(i = 0; i < 255; i++);        // Hold the clock low
      SCL = 1;                         // Release the clock
      while(!SCL);                     // Wait for open-drain
                                       // clock output to rise
      for(i = 0; i < 10; i++);         // Hold the clock high
      XBR1 = 0x00;                     // Disable Crossbar
   }

   Port_Init ();                       // Initialize Crossbar and GPIO

   // Turn off the LED before the test starts
   LED = 0;

   SMBus_Init ();                      // Configure and enable SMBus

   Timer4_Init ();                     // Configure and enable Timer4

   EIE1 |= 0x02;                       // Enable the SMBus interrupt

   EA = 1;                             // Global interrupt enable


   SFRPAGE = SMB0_PAGE;
   SI = 0;

// TEST CODE-------------------------------------------------------------------

   dat = 0;                            // Output data counter
   NUM_ERRORS = 0;                     // Error counter
   while (1)
   {
      // SMBus Write Sequence
      SMB_DATA_OUT = dat;              // Define next outgoing byte
      TARGET = SLAVE_ADDR;             // Target the F3xx/Si8250 Slave for next
                                       // SMBus transfer
      SMB_Write();                     // Initiate SMBus write

      // SMBus Read Sequence
      TARGET = SLAVE_ADDR;             // Target the F3xx/Si8250 Slave for next
                                       // SMBus transfer
      SMB_Read();

      // Check transfer data
      if(SMB_DATA_IN != SMB_DATA_OUT)  // Received data match transmit data?
      {
         NUM_ERRORS++;                 // Increment error counter if no match
      }

      // Indicate that an error has occurred (LED no longer lit)
      if (NUM_ERRORS > 0)
      {
         LED = 0;
      }
      else
      {
         LED = ~LED;
      }

      // Run to here to view the SMB_DATA_IN and SMB_DATA_OUT variables

      dat++;

      T0_Wait_ms (1);                  // Wait 1 ms until the next cycle
   }

// END TEST CODE---------------------------------------------------------------

}



//-----------------------------------------------------------------------------
// SMBus_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// The SMBus peripheral is configured as follows:
// - SMBus enabled
// - Assert Acknowledge low (AA bit = 1b)
// - Free and SCL low timeout detection enabled
//
void SMBus_Init (void)
{
    SMB0CN = 0x07;                      // Assert Acknowledge low (AA bit = 1b);
                                        // Enable SMBus Free timeout detect;
                                        // Enable SCL low timeout detect

    // SMBus clock rate (derived approximation from the Tlow and Thigh equations
    // in the SMB0CR register description)
    SMB0CR = 257 - (SYSCLK / (2 * SMB_FREQUENCY));

    SMB0ADR = MY_ADDR;                  // Set own slave address.

    SMB0CN |= 0x40;                     // Enable SMBus;
}

//-----------------------------------------------------------------------------
// Timer4_Init
//-----------------------------------------------------------------------------
//
// Return Value : None