ESP8266 Community Forum

- Thu Nov 24, 2016 10:36 am #58620 You mention that the 24CO8 is powered from 5V. It could be that the voltages on SDA and SCL lines are too low for the 24C08 to detect high consistently, as your pull-up resistors are from 3.3V. All the devices on the I2C bus should normally be powered from the same supply voltage, unless you are using a level shifter. You could try powering the 24C08 from 3.3V.

- Fri Nov 25, 2016 9:16 am #58659 What've you done with the write protect (WP) pin? From the datasheet:

This pin must be connected to either VSS or VCC.
If tied to VSS, normal memory operation is enabled
(read/write the entire memory 000-7FF).
If tied to VCC, WRITE operations are inhibited. The
entire memory will be write-protected. Read operations
are not affected.

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- Fri Nov 25, 2016 9:39 pm #58690

What've you done with the write protect (WP) pin? From the datasheet:

This pin must be connected to either VSS or VCC.
If tied to VSS, normal memory operation is enabled
(read/write the entire memory 000-7FF).
If tied to VCC, WRITE operations are inhibited. The
entire memory will be write-protected. Read operations
are not affected.

Thanks for your heads-up.
In fact, this was the very first thing that I've checked.

Digging on the Net, I was stumbled across this post: http://forum.arduino.cc/index.php?topic=62822.0, At this point I'm adapting the proposed code to make some test, but I suspect this can be the solution.

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- Sat Nov 26, 2016 8:38 am #58709 I think you didn't saw my previous answer : all 24C02/24C04/24C08/24C16 use 8 bits addressing instead of 16 bits addressing. Either use a different library that support it, or unsolder the chip and resolder 24C32 and higher.