I2C read and write to 24C01 eeprom

[richard]

you don't say what chip/osc you are using , consider this

The timing of the I2c

instructions is set so that standard speed devices(100kHz) will
be accessible at clock speeds up to 8MHz. Fast mode devices (400kHz) may be
used up to 20MHz. If it is desired to access a standard speed device at above
8MHz, the following DEFINE should be added to the program:
DEFINE I2C_SLOW 1

also read the data sheet for your eprom re
1. address command size
2 page size
writes that exceed a page in size or cross a page boundary can go wrong

read the manual and watch out for common myths

[Scampy]

Richard, I was using the OP's example hence the address, and trying to explain that as a word variable he needed to write the high and low bytes. It was not meant as an optimised example...

I used the following to send word variable values to a PCA chip.. it might not be tight code, it may not be "as it should" in the eyes of more experienced programmers, or it may not follow convention in the manual... But it works

    pcaChannel = 1  
    i2cControl = $6 + 4*pcaChannel                              
    I2CWRITE SDApin,SCLpin,i2cWriteAddress,i2cControl,[0,0,CH2_PWM.lowbyte,CH2_PWM.highbyte]

[richard]

I used the following to send word variable values to a PCA chip..

making a special case where endianness needs to be managed.

the pca chip requires the data sent low byte first, i2cread/write natively send high byte first.


to do that for a eprom is just a typing exercise

[Aussie Barry]

Hi Richard,

I did a project a while ago which stored word values to a 24LC02 EEPROM.
The only way I could get it to work was to use the lowbyte and highbyte method that Scampy mentioned.

Can you show me a snippet of your code that will successfully write a word value to EEPROM?

Cheers
Barry
VK2XBP

[richard]

no problem barry, this scans i2c bus reports valid addresses
and then reads and writes a mixed lot of word/byte vars

ps used a 24c08