AVR-Chat

This makes sense.  Did you truncate off the high bits down to (2048-
1)because the CPU you were using had only 2k bytes of EERPROM?  
Since the 128 has 4K, I guess then the address would be truncated to 
(4096-1)?

-Tony

--- In AVR-Chat@yahoogroups.com, David Kelly <dkelly@h...> wrote:
> On Tue, Apr 26, 2005 at 03:33:07PM -0000, arhodes19044 wrote:
> > 
> > OOOOPS.  That last part, 4 clock cyles, is pretty critical 
timing.  
> > I COULD disable interrupts for just step 4 and 5.
> > 
> > I can modify the code for the  Libc eeprom code to suit that.  
This 
> > is a very brief suspension. of the interrupts.
> 
> I haven't looked at the avr-libc version but wrote my own, it 
ain't that
> hard. However this code hasn't been tested yet:
> 
> //
> //	write to EEPROM
> //		addr is the address within the EEPROM
> //		cp is where to read data in RAM
> //		n is the number of 8 bit octets to copy
> //
> void
> ee_writes(uint16_t addr, void *cp, uint8_t n)
> {
> 	for( ; n ; n-- ) {
> 		wdt_reset();
> 		while( EECR & (1<<EEWE) )	//  wait until ready
> 			;
> 		
> 		EEAR = addr & (2048-1);	//  stripped to 11 bits, 2kB
> 		EEDR = *((uint8_t*)(cp)++);	//  looks frightening
> 		addr++;
> 	
> 		cli();			//  an IRQ would ruin this 
timing
> 		EECR |= (1<<EEMWE);	//  only stays set for 4 
clocks
> 		EECR |= (1<<EEWE);	//  hit EEWE before EEMWE 
clears
> 		sei();			//  assume IRQ was enabled
> 	}
> }
> 
> -- 
> David Kelly N4HHE, dkelly@H...
> 
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> Whom computers would destroy, they must first drive mad.