I2CWRITE on a 24LC512

[oslinux]

Hi all,

i've some problems writing with I2CWRITE to this EEPROM (24LC512), it's wired to the PIC and pulled up via two 4.7k res.

The pic sometime write, sometime not, this is the code:

'Dichiaro le variabili
W0 VAR WORD 'Memorizzazione I2C
SCL VAR PORTC.3 'Pin per la memoria I2C Clock
SDA VAR PORTC.4 'Pin per la memoria I2C Data
I VAR WORD 'Generica
Control VAR BYTE 'Costante byte di controllo EEPROM

Control = $A0 'Imposto il byte di controllo

OPTION_REG = %11101111

'Imposto la frequenza di oscillazione a 10 Mhz
DEFINE OSC 10

'Imposto le porte della PIC
TRISA = %11111111 'PortA Tutti input
TRISD = %11111111 'PortD Tutti input
TRISB = %00000001 'PortB Tutti output a parte 0
PORTB = %00000000 'PortB Tutti low
TRISC = %00000000 'PortC Tutti output
PORTC = %00000000 'PortC Tutti low

'Inizializzo l'EEPROM
EEPROMInit:
W0 = $0
for I = 0 to $18
I2cwrite SDA,SCL,CONTROL,I,[W0]
pause 10
next

in the initial state where all the addresses is FFFF, after i use this code i can see this state in the EEPROM:

0000: 1100 00FF 0000 0000 | ........
0008: 0000 FF11 0000 FF11 | ........
0010: FFFF FFFF FFFF FFFF | ........
0018: FFFF FFFF FFFF FFFF | ........
0020: FFFF FFFF FFFF FFFF | ........
0028: FFFF FFFF FFFF FFFF | ........
0030: FFFF FFFF FFFF FFFF | ........

Can you help me solving this problem?

Thank you,

Luca

EDIT:
I'm using a PIC16F877A

[sougata]

Hi,

The EEPROM you mentioned has address inputs on pins 1 and 2. Hope you have tried them to ground and not floating.
BTW this EEPROM supports page write mode. That is you can dump 128 bytes of data to the EEPROM and wait 10mS rather than waiting 10mS for every byte.

[GioppY]

Perhaps you forget "DEFINE I2C_SLOW 1"
Ciao

[Dave]

oslinux, You don't need the "DEFINE I2C_SLOW 1" statement as the normal speed of this EEPROM is 400Khz.

Dave Purola,
N8NTA

[oslinux]

No way, it's always writing the 90% (or less) of what it should...

[Dave]

oslinux, Try replacing the 4.7k pullups with 2.2k. Also, what are you doing with A0,A1, and A2 hardware address pins?

Dave Purola,
N8NTA

[oslinux]

A0, A1, A2 and WP are grounded, same problem with the 2.2K resistors, only some address are writed.