On Wed, 24 Sep 2008 08:20:12 -0700 (PDT), you wrote:

>I've written a few C functions for dealing with external page write
>eeprom. I have these functions:
>
>WriteEepFirstByte(address, data) // sets up address, sends data,
>increments static address counter, leaves /CS low
>
>WriteEepNextByte(data) // sends data, increments static address counter,
>does page write if incremented to new page, leaves /CS low
>
>WriteEepLastByte(data) // sends data, does page write, releases /CS
>
>WriteEepOnlyByte(address, data) // writes the specified byte to the
>specified address.
>

As multiple writes are often from sequential memory, a routine that reads/writes a number of
consecutive bytes will often cover most eventualities. Where you have a block of things like
parameters that need reading seperately,  this can be handled neatly by either using a union of an
array and individual chars/ints/whatever, or simply #defining the individual parameters as array
elements. 
e.g. char params[16];
#define param1 params[1]
#define param2 params[2]

Another thing that can make things neater is have procedures to read/write <n> bytes to/from memory,
splitting page writes as  required so the caller doesn't need  to worry about it. 
Then have macros that generate <n> from the size of variable used. 

below is an example in IAR C for ARM, but the same principle applies for other targets.

#define writeeeprom(adr,targ) dowriteeeprom(adr,sizeof(targ),(char*)&targ)


void dowriteeeprom(Int32U adr,Int32U nbytes,char *dest) 
  { Int32U i,lump;
  
  do {
    kickwatchdog();
  lump=(nbytes<=eepagesize)?nbytes:eepagesize;  
  i=eepagesize-(adr & (eepagesize-1)); // page size - offset within page - max we can write in 1 go
  if (lump>i) lump=i; // chop length to page boundary
  while(iistart(0xa2)) {I2C0CONCLR=8;} //wait not busy
    sendiic(adr>>8);
    sendiic(adr);
    adr+=lump;
    nbytes-=lump;
    do sendiic(*dest++); while(--lump); 
   iistop();

  }
  while (nbytes);
    
  }

This would be called like 

writeeprom(0,param1);

and the correct size of param1 would automatically be fed to the write routine. 


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist