//-----------------------------------------------------------------------------
// F31x_SMBus_Slave_Multibyte.c
//-----------------------------------------------------------------------------
// Copyright 2006 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// Example software to demonstrate the C8051F31x SMBus interface in Slave mode
// - Interrupt-driven SMBus implementation
// - Only slave states defined
// - Multi-byte SMBus data holders 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
// - supports multiple-byte writes and multiple-byte reads
// - Pinout:
//    P0.0 -> SDA (SMBus)
//    P0.1 -> SCL (SMBus)
//
//    P3.0 -> C2D (debugging interface)
//
//    P3.3 -> LED (on the 'F310 TB)
//
//    all other port pins unused
//
// How To Test:
//
// 1) Download code to a 'F31x device that is connected to a SMBus master.
// 2) Run the code.  The slave code will copy the write data to the read
//    data, 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 received is the same as the data written.
//
//
// FID:            31X000003
// Target:         C8051F31x
// Tool chain:     Keil C51 7.50 / Keil EVAL C51
// Command Line:   None
//
// Release 1.0
//    -Initial Revision (TP)
//    -30 MAR 2006
//

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

#include <C8051F310.h>

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

#define  SYSCLK         24500000       // 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

#define  NUM_BYTES_WR   3              // Number of bytes to write
                                       // Slave <- Master
#define  NUM_BYTES_RD   3              // Number of bytes to read
                                       // Slave -> Master

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

// Global holder for SMBus data.
// All receive data is written here
// NUM_BYTES_WR used because an SMBus write is Master->Slave
unsigned char SMB_DATA_IN[NUM_BYTES_WR];

// Global holder for SMBus data.
// All transmit data is read from here
// NUM_BYTES_RD used because an SMBus read is Slave->Master
unsigned char SMB_DATA_OUT[NUM_BYTES_RD];

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

// 16-bit SFR declarations
sfr16    TMR3RL   = 0x92;              // Timer3 reload registers
sfr16    TMR3     = 0x94;              // Timer3 counter registers

sbit LED = P3^3;                       // LED on port P3.3

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

void SMBus_Init (void);
void Timer1_Init (void);
void Timer3_Init (void);
void Port_Init (void);

void SMBus_ISR (void);
void Timer3_ISR (void);

//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------
//
// Main routine performs all configuration tasks, then waits for SMBus
// communication.
//
void main (void)
{
   unsigned char i;

   PCA0MD &= ~0x40;                    // WDTE = 0 (Disable watchdog
                                       // timer)

   OSCICN |= 0x03;                     // Set internal oscillator to highest
                                       // setting of 24500000

   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

   SMBus_Init ();                      // Configure and enable SMBus

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

   LED = 0;

   EA = 1;                             // Global interrupt enable

   // Initialize the outgoing data array in case a read is done before a
   // write
   for (i = 0; i < NUM_BYTES_RD; i++)
   {
      SMB_DATA_OUT[i] = 0xFD;
   }

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

      // Copy the data from the input array to the output array
      for (i = 0; i < NUM_BYTES_RD; i++)
      {
         SMB_DATA_OUT[i] = SMB_DATA_IN[i];
      }

      LED = ~LED;
   }
}

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

//-----------------------------------------------------------------------------
// SMBus_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 SMBus_Init (void)
{
   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;
}

//-----------------------------------------------------------------------------
// 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)
{