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big variables to EEPROM

 
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TimothyCarter



Joined: 08 Aug 2016
Posts: 22

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big variables to EEPROM
PostPosted: Thu Mar 31, 2022 9:51 am     Reply with quote

Should anyone find this useful, here are some helper functions for reading/writing 16 & 32 bit variables to EEPROM.

Note: as stated in the comments, variables should be stored in sequential bytes of EE.

Download link: https://gitlab.com/smilingtexan/ccs-picc-eeprom-large-var.git

Code:

/*
 * @file: eeprom_large.c
 * @author: T. Carter
 * @date: March 30, 2022
 *
 * This code is to provide methods to read and write 16-bit and 32-bit
 *   variables to the EEPROM of the PIC (it uses the built-in functions
 *   for read_eeprom and write_eeprom)
 *
 */

#ifndef _STDINT
   #include <stdint.h>         // need this library from the CCS drivers folder
#endif

// The CCS built-in function read_eeprom will read and return one byte
//    from the EEPROM memory. The following two functions are added
//    to return a 16-bit and 32-bit unsigned int respectively.
// The macro __EEADDRESS__ is defined in the processor header file as
//    either an 8-bit or 16-bit variable depending on EEPROM size.
// For the 16-bit and 32-bit methods of read & write; the addr variable
//    should be the EEPROM address of the LSB (least-significant byte)
//    Thus, the EEPROM addresses for the 16-bit and 32-bit variables
//    should be sequential or things can get really confusing

uint16_t read_eeprom16 (__EEADDRESS__ addr)
{
   uint8_t low, high;
   low = read_eeprom(addr++);       // read from eeprom at addr and then increment addr
   high = read_eeprom(addr);
   return(make16(high, low));
}

uint32_t read_eeprom32 (__EEADDRESS__ addr)
{
   uint8_t low, high;
   uint16_t wLow, wHigh; 
   low = read_eeprom(addr++);       // read from eeprom at addr and then increment addr
   high = read_eeprom(addr++);
   wLow = make16(high, low);
   low = read_eeprom(addr++);
   high = read_eeprom(addr);
   wHigh = make16(high, low);
   return(make32(wHigh, wLow));
}

// The following eeprom_write function only writes the data to EEPROM if
//    it is different from what is at that addr
void eeprom_write (__EEADDRESS__ addr, uint8_t data)
{
   uint8_t temp = read_eeprom(addr);
   if (data != temp)
   {
      write_eeprom(addr, data);
   }
}

// The following two functions are provided to write 16-bit and 32-bit
//    variables to the EEPROM; similar to the read_eeprom functions above
void write_eeprom16 (__EEADDRESS__ addr, uint16_t data)
{
   uint8_t smallData = make8(data, 0);
   eeprom_write(addr++, smallData);
   smallData = make8(data, 1);
   eeprom_write(addr, smallData);
}

void write_eeprom32 (__EEADDRESS__ addr, uint32_t data)
{
   uint8_t smallData = make8(data, 0);
   eeprom_write(addr++, smallData);
   smallData = make8(data, 1);
   eeprom_write(addr++, smallData);
   smallData = make8(data, 2);
   eeprom_write(addr++, smallData);
   smallData = make8(data, 3);
   eeprom_write(addr, smallData);
}

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Ttelmah



Joined: 11 Mar 2010
Posts: 19195

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PostPosted: Mon Apr 04, 2022 6:30 am     Reply with quote

Just FYI, the compiler already has code to do this (and for several more
types as well). Look at 'internal_eeprom.c', which has routines to handle

int1, int16, int32, float, and for PCD, float48, float64 etc..
TimothyCarter



Joined: 08 Aug 2016
Posts: 22

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I figured CCS had something ...
PostPosted: Tue Apr 12, 2022 3:20 pm     Reply with quote

Ttelmah wrote:
Just FYI, the compiler already has code to do this (and for several more
types as well). Look at 'internal_eeprom.c', which has routines to handle

int1, int16, int32, float, and for PCD, float48, float64 etc..


I figured they must have had something, but could not find it at the time I wrote this. (Originally written a couple of years ago.)
_________________
“Computer science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter.”
- Eric S. Raymond
Ttelmah



Joined: 11 Mar 2010
Posts: 19195

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PostPosted: Mon Apr 25, 2022 1:14 am     Reply with quote

I think perhaps they need to do something like the 'readme', with a list
of the driver files and what they do.
The file goes back to 2012, so should have been with your compiler
'a couple of years ago'. Very Happy
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