You are reading the high byte twice, and adding them together.  Eliminate:
test2 =3D test2 + (readEepromByte(0x01)<<8);
Delay10TCYx(100);

Kerry



Yigit Turgut wrote:
> I modified a bit your code to guarantee the operation ;
>
> test1 =3D 512;
>
> writeEepromByte(0x00, test1t&0xFF);
> Delay10TCYx(200);
> writeEepromByte(0x01, test1>>8);
> Delay10TCYx(200);
> test2 =3D readEepromByte(0x00+ (readEepromByte(0x01)<<8));
> Delay10TCYx(100);
> test2 =3D test2 + (readEepromByte(0x01)<<8);
> Delay10TCYx(100);
>
> f( test1=3D=3Dtest2) {
>  PORTBbits.RB7 =3D1; }
>
> Now RB7 is low always, it's not changing into high state.
>
> On Fri, Oct 28, 2011 at 5:26 PM, Kerry Wentworth
> <kwentworth@skunkworksnh.com> wrote:
>  =20
>> You can write/read a 16 bit integer (512 requires a 16 bit integer) by:
>>
>> // Write
>> test1 =3D 512;
>> writeEepromByte(0x00, test1&0xFF);
>> writeEepromByte(0x01, test1>>8);
>>
>> // Read
>> test2 =3D readEepromByte(0x00)+(readEepromByte(0x01)<<8);
>>
>> // Check
>> if( test1=3D=3Dtest2) {
>> PORTBbits.RB7 =3D1; }
>>
>> Kerry
>>
>>
>> Yigit Turgut wrote:
>>    =20
>>> Hi all,
>>>
>>> I am trying to write an 8bit integer to internal eeprom of a 18f2550
>>> by the following functions ;
>>>
>>> #define byte unsigned char
>>> #define BYTE_ADDR 0
>>> int test1, test2;
>>>
>>> void writeEepromByte(byte addr, byte data) {
>>> INTCONbits.GIE =3D 0;
>>> EECON1bits.EEPGD =3D 0;
>>> EECON1bits.CFGS =3D 0;
>>> EECON1bits.WREN =3D 1;
>>> EEADR =3D addr;
>>> EEDATA =3D data;
>>> EECON2 =3D 0x55;
>>> EECON2 =3D 0xaa;
>>> EECON1bits.WR =3D 1;
>>> while (!PIR2bits.EEIF) ;
>>> PIR2bits.EEIF =3D 0;
>>> INTCONbits.GIE =3D 1;
>>> }
>>>
>>> byte readEepromByte(unsigned char addr) {
>>> EECON1bits.EEPGD =3D 0;
>>> EECON1bits.CFGS =3D 0;
>>> EEADR =3D addr;
>>> EECON1bits.RD =3D 1;
>>> return EEDATA;
>>> }
>>>
>>> And to test it I use ;
>>>
>>> if ( PORTBbits.RB2 =3D=3D 0 ){
>>> Delay10KTCYx( 50 );
>>> test1 =3D 512;
>>> writeEepromByte(0x00, test1);
>>> Delay10TCYx(200);
>>> test2 =3D readEepromByte(0x00);
>>> Delay10TCYx(100);
>>> }
>>>
>>> if( test1=3D=3Dtest2<<8) {
>>> PORTBbits.RB7 =3D1; }
>>>
>>> All ports are configured correctly and board is functioning well. With
>>> a push of the button at RB2, value 512 should be stored in eeprom.
>>> Actually least significant 8bits of test1 will be written because it's
>>> a one-bye space that it's writing to. Even if so,  test1=3D=3Dtest2<<8
>>> this expression should be valid and RB7 is should be set high. None of
>>> this happens, nothing happens at all. Is this a problem because only
>>> bytes can be written to eeprom ? It should be pretty straightforward
>>> to write/read 8 bit integer to/from internal eeprom/
>>>
>>>      =20
>> --
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>>
>>    =20
>
>  =20

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