f06x_smbus_slave.c

This example demonstrates how the C8051F06x SMBus interface can communicate // with a 256 byte I2C

//-----------------------------------------------------------------------------
// F06x_SMBus_Slave.c
//-----------------------------------------------------------------------------
// Copyright 2006 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// Example software to demonstrate the C8051F06x SMBus interface in Slave mode
// - Interrupt-driven SMBus implementation
// - Only slave states defined
// - 1-byte SMBus data holder used for both transmit and receive
// - Timer4 used by SMBus for SCL low timeout detection
// - 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 'F06x device that is connected to a SMBus master.
// 2) 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.
//
//
// FID:            06X000005
// Target:         C8051F06x
// Tool chain:     Keil C51 7.50 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0
//    -Initial Revision (TP)
//    -20 APR 2006
//

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

#include <C8051F060.h>                 // SFR declarations

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

#define  SYSCLK         3062500L       // 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  MY_ADDR        0xF0           // Address of this SMBus device

// SMBus Buffer Size
#define  SMB_BUFF_SIZE  0x08           // Defines the maximum number of bytes
                                       // that can be sent or received in a
                                       // single transfer

#define  SMB_BUS_ERROR  0x00           // (all modes) BUS ERROR
#define  SMB_SROADACK   0x60           // (SR) SMB's own slave address + W
                                       //    rec'vd; ACK transmitted
#define  SMB_SRGADACK   0x70           // (SR) general call address rec'vd;
                                       //    ACK transmitted
#define  SMB_SRODBACK   0x80           // (SR) data byte received under own
                                       //    slave address; ACK returned
#define  SMB_SRODBNACK  0x88           // (SR) data byte received under own
                                       //    slave address; NACK returned
#define  SMB_SRGDBACK   0x90           // (SR) data byte received under general
                                       //    call address; ACK returned
#define  SMB_SRGDBNACK  0x98           // (SR) data byte received under general
                                       //    call address; NACK returned
#define  SMB_SRSTOP     0xa0           // (SR) STOP or repeated START received
                                       //    while addressed as a slave
#define  SMB_STOADACK   0xa8           // (ST) SMB's own slave address + R
                                       //    rec'vd; ACK transmitted
#define  SMB_STDBACK    0xb8           // (ST) data byte transmitted; ACK
                                       //    rec'ed
#define  SMB_STDBNACK   0xc0           // (ST) data byte transmitted; NACK
                                       //    rec'ed
#define  SMB_STDBLAST   0xc8           // (ST) last data byte transmitted
                                       //    (AA=0); ACK received
#define  SMB_SCLHIGHTO  0xd0           // (ST & SR) SCL clock high timer per
                                       //    SMB0CR timed out (FTE=1)
#define  SMB_IDLE       0xf8           // (all modes) Idle

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

unsigned char 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.

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

sbit LED = P1^6;                       // LED on P1.6

//-----------------------------------------------------------------------------
// 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);

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

void MAIN (void)
{
   WDTCN = 0xde;                       // Disable watchdog timer
   WDTCN = 0xad;

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

   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;

   SMB_DATA = 0xFD;                    // Initialize SMBus data holder

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

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

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This routine initializes the system clock to use the internal oscillator
// at 3.0625 MHz (24.5 / 8 MHz).
//
void SYSCLK_Init (void)
{
   char SFRPAGE_SAVE = SFRPAGE;        // Save Current SFR page

   SFRPAGE = CONFIG_PAGE;              // Set SFR page

   OSCICN = 0x80;                      // Set internal oscillator to run
                                       // at 1/8 its maximum frequency

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

   SFRPAGE = SFRPAGE_SAVE;             // Restore SFR page
                                       // detector
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Configure the Crossbar and GPIO ports.
//
// P0.0   digital   open-drain    SMBus SDA
// P0.1   digital   open-drain    SMBus SCL
//
// P1.6   digital   push-pull     LED
//
// all other port pins unused
//
void PORT_Init (void)
{
   char SFRPAGE_SAVE = SFRPAGE;        // Save Current SFR page

   SFRPAGE = CONFIG_PAGE;