TMS320F28035: I2C EEPROM Example Code

//###########################################################################
//
//!  \addtogroup f2803x_example_list
//!  <h1>I2C EEPROM(i2c_eeprom)</h1>
//!
//!  This program requires an external I2C EEPROM connected to
//!  the I2C bus at address 0x50.
//!  This program will write 1-14 words to EEPROM and read them back.
//!  The data written and the EEPROM address written to are contained
//!  in the message structure, \b I2cMsgOut1. The data read back will be
//!  contained in the message structure \b I2cMsgIn1.
//!
//!  \note This program will only work on kits that have an on-board I2C EEPROM.
//!  (e.g. F2803x eZdsp)
//!
//!  \b Watch \b Variables \n
//!  - I2cMsgIn1
//!  - I2cMsgOut1
//
//###########################################################################
// $TI Release: F2803x C/C++ Header Files and Peripheral Examples V130 $
// $Release Date: May  8, 2015 $
// $Copyright: Copyright (C) 2009-2015 Texas Instruments Incorporated -
//             http://www.ti.com/ ALL RIGHTS RESERVED $
//###########################################################################

#include "DSP28x_Project.h"     // Device Headerfile and Examples Include File

// Note: I2C Macros used in this example can be found in the
// DSP2803x_I2C_defines.h file

// Prototype statements for functions found within this file.
void   I2CA_Init(void);
Uint16 I2CA_WriteData(struct I2CMSG *msg);
Uint16 I2CA_ReadData(struct I2CMSG *msg);
__interrupt void i2c_int1a_isr(void);
void pass(void);
void fail(void);

#define I2C_SLAVE_ADDR        0x50
#define I2C_NUMBYTES          2
#define I2C_EEPROM_HIGH_ADDR  0x00
#define I2C_EEPROM_LOW_ADDR   0x30

// Global variables
// Two bytes will be used for the outgoing address,
// thus only setup 14 bytes maximum
struct I2CMSG I2cMsgOut1={I2C_MSGSTAT_SEND_WITHSTOP,
                          I2C_SLAVE_ADDR,
                          I2C_NUMBYTES,
                          I2C_EEPROM_HIGH_ADDR,
                          I2C_EEPROM_LOW_ADDR,
                          0x12,                   // Msg Byte 1
                          0x34};                  // Msg Byte 2

struct I2CMSG I2cMsgIn1={ I2C_MSGSTAT_SEND_NOSTOP,
                          I2C_SLAVE_ADDR,
                          I2C_NUMBYTES,
                          I2C_EEPROM_HIGH_ADDR,
                          I2C_EEPROM_LOW_ADDR};

struct I2CMSG *CurrentMsgPtr;				// Used in interrupts
Uint16 PassCount;
Uint16 FailCount;

void main(void)
{
   Uint16 Error;
   Uint16 i;

   CurrentMsgPtr = &I2cMsgOut1;

// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2803x_SysCtrl.c file.
   InitSysCtrl();

// Step 2. Initialize GPIO:
// This example function is found in the DSP2803x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio();
// Setup only the GP I/O only for I2C functionality
   InitI2CGpio();

// Step 3. Clear all interrupts and initialize PIE vector table:
// Disable CPU interrupts
   DINT;

// Initialize PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared.
// This function is found in the DSP2803x_PieCtrl.c file.
   InitPieCtrl();

// Disable CPU interrupts and clear all CPU interrupt flags:
   IER = 0x0000;
   IFR = 0x0000;

// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
// This will populate the entire table, even if the interrupt
// is not used in this example.  This is useful for debug purposes.
// The shell ISR routines are found in DSP2803x_DefaultIsr.c.
// This function is found in DSP2803x_PieVect.c.
   InitPieVectTable();

// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
   EALLOW;	// This is needed to write to EALLOW protected registers
   PieVectTable.I2CINT1A = &i2c_int1a_isr;
   EDIS;   // This is needed to disable write to EALLOW protected registers

// Step 4. Initialize the I2C Peripheral:
   I2CA_Init();

// Step 5. User specific code

   // Clear Counters
   PassCount = 0;
   FailCount = 0;

   // Clear incoming message buffer
   for (i = 0; i < I2C_MAX_BUFFER_SIZE; i++)
   {
       I2cMsgIn1.MsgBuffer[i] = 0x0000;
   }

// Enable interrupts required for this example

// Enable I2C interrupt 1 in the PIE: Group 8 interrupt 1
   PieCtrlRegs.PIEIER8.bit.INTx1 = 1;

// Enable CPU INT8 which is connected to PIE group 8
   IER |= M_INT8;
   EINT;

   // Application loop
   for(;;)
   {
      //////////////////////////////////
      // Write data to EEPROM section //
      //////////////////////////////////

      // Check the outgoing message to see if it should be sent.
      // In this example it is initialized to send with a stop bit.
      if(I2cMsgOut1.MsgStatus == I2C_MSGSTAT_SEND_WITHSTOP)
      {
         Error = I2CA_WriteData(&I2cMsgOut1);
         // If communication is correctly initiated, set msg status to busy
         // and update CurrentMsgPtr for the interrupt service routine.
         // Otherwise, do nothing and try again next loop. Once message is
         // initiated, the I2C interrupts will handle the rest. Search for
         // i2c_int1a_isr in the i2c_eeprom_isr.c file.
         if (Error == I2C_SUCCESS)
         {
            CurrentMsgPtr = &I2cMsgOut1;
            I2cMsgOut1.MsgStatus = I2C_MSGSTAT_WRITE_BUSY;
         }
      }  // end of write section

      ///////////////////////////////////
      // Read data from EEPROM section //
      ///////////////////////////////////

      // Check outgoing message status. Bypass read section if status is
      // not inactive.
      if (I2cMsgOut1.MsgStatus == I2C_MSGSTAT_INACTIVE)
      {
         // Check incoming message status.
         if(I2cMsgIn1.MsgStatus == I2C_MSGSTAT_SEND_NOSTOP)
         {
            // EEPROM address setup portion
            while(I2CA_ReadData(&I2cMsgIn1) != I2C_SUCCESS)
            {
               // Maybe setup an attempt counter to break an infinite while
               // loop. The EEPROM will send back a NACK while it is performing
               // a write operation. Even though the write communique is
               // complete at this point, the EEPROM could still be busy
               // programming the data. Therefore, multiple attempts are
               // necessary.
            }
            // Update current message pointer and message status
            CurrentMsgPtr = &I2cMsgIn1;
            I2cMsgIn1.MsgStatus = I2C_MSGSTAT_SEND_NOSTOP_BUSY;
         }

         // Once message has progressed past setting up the internal address
         // of the EEPROM, send a restart to read the data bytes from the
         // EEPROM. Complete the communique with a stop bit. MsgStatus is
         // updated in the interrupt service routine.
         else if(I2cMsgIn1.MsgStatus == I2C_MSGSTAT_RESTART)
         {
            // Read data portion
            while(I2CA_ReadData(&I2cMsgIn1) != I2C_SUCCESS)
            {
               // Maybe setup an attempt counter to break an infinite while
               // loop.
            }
            // Update current message pointer and message status
            CurrentMsgPtr = &I2cMsgIn1;
            I2cMsgIn1.MsgStatus = I2C_MSGSTAT_READ_BUSY;
         }
      }  // end of read section
   }   // end of for(;;)
}   // end of main

void I2CA_Init(void)
{
   // Initialize I2C
   I2caRegs.I2CSAR = 0x0050;		// Slave address - EEPROM control code

   I2caRegs.I2CPSC.all = 6;		    // Prescaler - need 7-12 Mhz on module clk
   I2caRegs.I2CCLKL = 10;			// NOTE: must be non zero
   I2caRegs.I2CCLKH = 5;			// NOTE: must be non zero
   I2caRegs.I2CIER.all = 0x24;		// Enable SCD & ARDY interrupts

   I2caRegs.I2CMDR.all = 0x0020;	// Take I2C out of reset
   									// Stop I2C when suspended

   I2caRegs.I2CFFTX.all = 0x6000;	// Enable FIFO mode and TXFIFO
   I2caRegs.I2CFFRX.all = 0x2040;	// Enable RXFIFO, clear RXFFINT,

   return;
}

Uint16 I2CA_WriteData(struct I2CMSG *msg)
{
   Uint16 i;

   // Wait until the STP bit is cleared from any previous master communication.
   // Clearing of this bit by the module is delayed until after the SCD bit is
   // set. If this bit is not checked prior to initiating a new message, the
   // I2C could get confused.
   if (I2caRegs.I2CMDR.bit.STP == 1)
   {
      return I2C_STP_NOT_READY_ERROR;
   }

   // Setup slave address
   I2caRegs.I2CSAR = msg->SlaveAddress;

   // Check if bus busy
   if (I2caRegs.I2CSTR.bit.BB == 1)
   {
      return I2C_BUS_BUSY_ERROR;
   }

   // Setup number of bytes to send
   // MsgBuffer + Address
   I2caRegs.I2CCNT = msg->NumOfBytes+2;

   // Setup data to send
   I2caRegs.I2CDXR = msg->MemoryHighAddr;
   I2caRegs.I2CDXR = msg->MemoryLowAddr;
// for (i=0; i<msg->NumOfBytes-2; i++)
   for (i=0; i<msg->NumOfBytes; i++)

   {
      I2caRegs.I2CDXR = *(msg->MsgBuffer+i);
   }

   // Send start as master transmitter
   I2caRegs.I2CMDR.all = 0x6E20;

   return I2C_SUCCESS;
}

Uint16 I2CA_ReadData(struct I2CMSG *msg)
{
   // Wait until the STP bit is cleared from any previous master communication.
   // Clearing of this bit by the module is delayed until after the SCD bit is
   // set. If this bit is not checked prior to initiating a new message, the
   // I2C could get confused.
   if (I2caRegs.I2CMDR.bit.STP == 1)
   {
      return I2C_STP_NOT_READY_ERROR;
   }

   I2caRegs.I2CSAR = msg->SlaveAddress;

   if(msg->MsgStatus == I2C_MSGSTAT_SEND_NOSTOP)
   {
      // Check if bus busy
      if (I2caRegs.I2CSTR.bit.BB == 1)
      {
         return I2C_BUS_BUSY_ERROR;
      }
      I2caRegs.I2CCNT = 2;
      I2caRegs.I2CDXR = msg->MemoryHighAddr;
      I2caRegs.I2CDXR = msg->MemoryLowAddr;
      I2caRegs.I2CMDR.all = 0x2620;			// Send data to setup EEPROM address
   }
   else if(msg->MsgStatus == I2C_MSGSTAT_RESTART)
   {
      I2caRegs.I2CCNT = msg->NumOfBytes;	// Setup how many bytes to expect
      I2caRegs.I2CMDR.all = 0x2C20;			// Send restart as master receiver
   }

   return I2C_SUCCESS;
}

__interrupt void i2c_int1a_isr(void)     // I2C-A
{
   Uint16 IntSource, i;

   // Read interrupt source
   IntSource = I2caRegs.I2CISRC.all;

   // Interrupt source = stop condition detected
   if(IntSource == I2C_SCD_ISRC)
   {
      // If completed message was writing data, reset msg to inactive state
      if (CurrentMsgPtr->MsgStatus == I2C_MSGSTAT_WRITE_BUSY)
      {
         CurrentMsgPtr->MsgStatus = I2C_MSGSTAT_INACTIVE;
      }
      else
      {
         // If a message receives a NACK during the address setup portion of the
         // EEPROM read, the code further below included in the register access ready
         // interrupt source code will generate a stop condition. After the stop
         // condition is received (here), set the message status to try again.
         // User may want to limit the number of retries before generating an error.
         if(CurrentMsgPtr->MsgStatus == I2C_MSGSTAT_SEND_NOSTOP_BUSY)
         {
            CurrentMsgPtr->MsgStatus = I2C_MSGSTAT_SEND_NOSTOP;
         }
         // If completed message was reading EEPROM data, reset msg to inactive state
         // and read data from FIFO.
         else if (CurrentMsgPtr->MsgStatus == I2C_MSGSTAT_READ_BUSY)
         {
            CurrentMsgPtr->MsgStatus = I2C_MSGSTAT_INACTIVE;
            for(i=0; i < I2C_NUMBYTES; i++)
            {
              CurrentMsgPtr->MsgBuffer[i] = I2caRegs.I2CDRR;
            }
         {
         // Check received data
         for(i=0; i < I2C_NUMBYTES; i++)
         {
            if(I2cMsgIn1.MsgBuffer[i] == I2cMsgOut1.MsgBuffer[i])
            {
                PassCount++;
            }
            else
            {
                FailCount++;
            }
         }
         if(PassCount == I2C_NUMBYTES)
         {
            pass();
         }
         else
         {
            fail();
         }

      }

    }
      }
   }  // end of stop condition detected

   // Interrupt source = Register Access Ready
   // This interrupt is used to determine when the EEPROM address setup portion of the
   // read data communication is complete. Since no stop bit is commanded, this flag
   // tells us when the message has been sent instead of the SCD flag. If a NACK is
   // received, clear the NACK bit and command a stop. Otherwise, move on to the read
   // data portion of the communication.
   else if(IntSource == I2C_ARDY_ISRC)
   {
      if(I2caRegs.I2CSTR.bit.NACK == 1)
      {
         I2caRegs.I2CMDR.bit.STP = 1;
         I2caRegs.I2CSTR.all = I2C_CLR_NACK_BIT;
      }
      else if(CurrentMsgPtr->MsgStatus == I2C_MSGSTAT_SEND_NOSTOP_BUSY)
      {
         CurrentMsgPtr->MsgStatus = I2C_MSGSTAT_RESTART;
      }
   }  // end of register access ready

   else
   {
      // Generate some error due to invalid interrupt source
      __asm("   ESTOP0");
   }

   // Enable future I2C (PIE Group 8) interrupts
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP8;
}

void pass()
{
    __asm("   ESTOP0");
    for(;;);
}

void fail()
{
    __asm("   ESTOP0");
    for(;;);
}

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// No more.
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