at24c.c

this document is source code for arm9 of atmel

/*-----------------------------------------------------------------------------
*         ATMEL Microcontroller Software Support  -  ROUSSET  -
*------------------------------------------------------------------------------
* The software is delivered "AS IS" without warranty or condition of any
* kind, either express, implied or statutory. This includes without
* limitation any warranty or condition with respect to merchantability or
* fitness for any particular purpose, or against the infringements of
* intellectual property rights of others.
*------------------------------------------------------------------------------
* File Name    : at24c.c
* Object       : ATMEL AT24C Two-wire Serial EEPROM low level functions
*
* Version | mm | dd | yy | author :
*  1.0      12   14   06    PFi   : Creation
*  1.1      12   04   07    PFi   : Update of Multiple read/write function
*                                   according to the new TWI doc.
*  1.11     14   08   07    PFi   : Cleanup.
*                                 : AT91F_AT24C_MemoryReset Corrected to match
*                                 : reset sequence from ATMEL AT24C datasheet
*------------------------------------------------------------------------------
* 1)Description:
*
* A set of standalone read or write functions are provided.
*
* AT91F_AT24C_WriteByte
* AT91F_AT24C_WritePage
* AT91F_AT24C_ReadByte
* AT91F_AT24C_ReadPage
* AT91F_AT24C_SequentialRead
*
* TO DO: Add NACK management, due to AT91SAM7S TWI errata, for functions
* which are not using the TWI Lib functions.
*----------------------------------------------------------------------------*/
/*---------------------------- Include files --------------------------------*/
#include "at24c.h"
#include "board.h"
#include "..\common\init.h"
#include "..\common\lib_twi.h"

/*---------------------------  Constants definition -------------------------*/
/* value of the PIT value to have 333ns @ 48 MHz
668 -1 since real time out = PIV + 1 */
#define PIT_PIV_MILI_SECOND_VALUE  0x667

/* value of the PIT value to have 333ns @ 48 MHz
3 -1 since real time out = PIV + 1 */
#define PIT_PIV_MICRO_SECOND_VALUE  0x2

/*----------------------------- Global Variables ----------------------------*/

/*----------------------------- External Functions --------------------------*/
/*-----------------------------------------------------------------------------
* Wait function with the Periodic Interval Timer (PIT)
* The wait time is from 1ms to 999ms.
-----------------------------------------------------------------------------*/
void AT91F_AT24C_WaitMiliSecond (unsigned int MiliSeconds)
{
   unsigned int PitStatus = 0;     /* Status register of the PIT */
   unsigned int PitLoop = 0;    /* Store the number of PIT Loop */

   AT91C_BASE_PITC->PITC_PIMR = AT91C_PITC_PITEN|PIT_PIV_MILI_SECOND_VALUE;

   for( PitLoop=0; PitLoop <(MiliSeconds*3);)   /* One PIT loop equals 333ms */
   {
    /* Wait for the PIT counter overflow occurs */
    while ((AT91C_BASE_PITC->PITC_PISR & AT91C_PITC_PITS)==0);
    /* Read the PIT Interval Value Reg. to clear it for the next overflow */
    PitStatus = AT91C_BASE_PITC->PITC_PIVR ;
    /* dummy access to avoid IAR warning */
    PitStatus = PitStatus ;
    PitLoop++;
   }
}


/*-----------------------------------------------------------------------------
* Wait function with the Periodic Interval Timer (PIT)
* The wait time is from 1us to 999us.
-----------------------------------------------------------------------------*/
void AT91F_AT24C_WaitMicroSecond (unsigned int MicroSecond)
{
   unsigned int PitStatus = 0;     /* Status register of the PIT */
   unsigned int PitLoop = 0;    /* Store the number of PIT Loop */

   AT91C_BASE_PITC->PITC_PIMR = AT91C_PITC_PITEN|PIT_PIV_MICRO_SECOND_VALUE;

   for( PitLoop=0; PitLoop <(MicroSecond);)   /* One PIT loop equals 333ns */
   {
    /* Wait for the PIT counter overflow occurs */
    while ((AT91C_BASE_PITC->PITC_PISR & AT91C_PITC_PITS)==0);
    /* Read the PIT Interval Value Reg. to clear it for the next overflow */
    PitStatus = AT91C_BASE_PITC->PITC_PIVR ;
    /* dummy access to avoid IAR warning */
    PitStatus = PitStatus ;
    PitLoop++;
   }
}

/*-----------------------------------------------------------------------------
Function: AT91F_AT24C_WriteByte(..;..;..)

Arguments:
- <struct at24c *ptAt24c> : Structure of an AT24C Two-wire Eeprom
- <char Data2Write>: The data to write into the eeprom
- <unsigned int Address>: Address where to write

Comments:
This function uses a two bytes internal address (IADR) in relation of the
Eeprom's Internal "Word Address".
Return Value: None. No write error checking is done.
-----------------------------------------------------------------------------*/
void AT91F_AT24C_WriteByte (struct at24c *ptAt24c,
                            char Data2Write,
                            unsigned int Address)
{
  unsigned int WordAddress;
  unsigned int SlaveAddress;

  /* 17th bit of the word address. Applicable to the AT24C1024 only */
  unsigned char p0=0;

   if (ptAt24c->EepromName == AT24C1024)
  {
    if ( Address > 0xFFFF) {
        p0 = 1;
        /* Mask the 17th bit to get the 16th LSB */
        WordAddress = Address & 0xFFFF ;
        SlaveAddress = ptAt24c->SlaveAddress + (p0<<16) ;
    }

   else {
    SlaveAddress = ptAt24c->SlaveAddress ;
    WordAddress = Address ;
    }
  }

  AT91F_TWI_WriteSingleIadr(AT91C_BASE_TWI,
                      SlaveAddress,
                      WordAddress,
                      AT91C_TWI_IADRSZ_2_BYTE,
                      &Data2Write);

   /* Wait 10ms before sending another start.
    See Twr time spec. in the datasheet */
    AT91F_AT24C_WaitMiliSecond (10);


}

/*-----------------------------------------------------------------------------
Function: AT91F_AT24C_WritePage(..;..;..)

Arguments:
- <struct at24c *ptAt24c> : Structure of an AT24C Two-wire Eeprom
- <char *Buffer>: The data (*buffer) to write into the eeprom
- <NumOfBytes>: Size of the buffer
- <unsigned int AddressOffSet>: Address offset form the page address

Comments:
This function uses a two bytes internal address (IADR) in relation of the
Eeprom's Internal "Word Address". NACK error not handled

Return Value: None. No write error checking is done.
-----------------------------------------------------------------------------*/
void AT91F_AT24C_WritePage (struct at24c *ptAt24c,
                            char *Buffer,
                            unsigned int NumOfBytes,
                            unsigned int PageNumber,
                            unsigned int AddressOffSet)
{
  unsigned int WordAddress;
  unsigned int SlaveAddress;
  unsigned int Count ;
  unsigned int status;

  /* 17th bit of the word address. Applicable to the AT24C1024 only */
  unsigned char p0=0;

  if (ptAt24c->EepromName == AT24C1024)
  {
    if ( ( (PageNumber*ptAt24c->PageSize) + AddressOffSet ) > 0xFFFF) {
        p0 = 1;
        /* Mask the 17th bit to get the 16th LSB */
        WordAddress = ( (PageNumber*ptAt24c->PageSize) + AddressOffSet ) & 0xFFFF ;
        SlaveAddress = ptAt24c->SlaveAddress + (p0<<16) ;
    }

   else
   {
     SlaveAddress = ptAt24c->SlaveAddress ;
     WordAddress = (PageNumber*ptAt24c->PageSize) + AddressOffSet ;
   }
  }

  /****************************************************************************/
  /* Speed improvement w/ large buffer, TWI is accessed without calling TWI    */
  /* functions.                                                                */
  /****************************************************************************/

  /* Enable Master Mode of the TWI */
  AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN ;

  /* Set the TWI Master Mode Register */
  AT91C_BASE_TWI->TWI_MMR =  SlaveAddress & ~AT91C_TWI_MREAD | AT91C_TWI_IADRSZ_2_BYTE;

  /* Set the internal address to access the wanted page */
  AT91C_BASE_TWI->TWI_IADR =   WordAddress ;

  /* Wait until TXRDY is high to transmit the next data */
  status = AT91C_BASE_TWI->TWI_SR;
  while (!(status & AT91C_TWI_TXRDY))
    status = AT91C_BASE_TWI->TWI_SR;

  /* Send the buffer to the page */
  for ( Count=0; Count < NumOfBytes ;Count++ )
  {
    AT91C_BASE_TWI->TWI_THR = *Buffer++;

    /* Wait until TXRDY is high to transmit the next data */
    status = AT91C_BASE_TWI->TWI_SR;
    while (!(status & AT91C_TWI_TXRDY))
      status = AT91C_BASE_TWI->TWI_SR;
  }

  /* Wait for the Transmit complete is set */
  status = AT91C_BASE_TWI->TWI_SR;
  while (!(status & AT91C_TWI_TXCOMP))
    status = AT91C_BASE_TWI->TWI_SR;

  /* Wait 10ms before sending another start.
  See Twr time spec. in the datasheet */
  AT91F_AT24C_WaitMiliSecond (10);

}


/*-----------------------------------------------------------------------------
Function: AT91F_AT24C_ReadByte(..;..;..)

Arguments:
- <struct at24c *ptAt24c> : Structure of an AT24C Two-wire Eeprom
- <unsigned int Address>: Address to read

Comments:
This function uses a two bytes internal address (IADR) in relation of the
Eeprom's Internal "Word Address".

Return Value: None. No read error checking is done.
-----------------------------------------------------------------------------*/
char AT91F_AT24C_ReadByte (struct at24c *ptAt24c,
                           unsigned int Address)
{
  unsigned int WordAddress;
  unsigned int SlaveAddress;
  char Data2Read ;

  /* 17th bit of the word address. Applicable to the AT24C1024 only */
  unsigned char p0=0;


   if (ptAt24c->EepromName == AT24C1024)
  {
    if ( Address > 0xFFFF) {
        p0 = 1;
        /* Mask the 17th bit to get the 16th LSB */
        WordAddress = Address & 0xFFFF ;
        SlaveAddress = ptAt24c->SlaveAddress + (p0<<16) ;
    }