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PCA9500 I2C NACK issue in EEPROM

Question asked by Jay Yeh on Feb 11, 2020

Hi

I am now using PCA9500 to design a product.
PCA9500 is connected with a MCU via i2c with A2 pin to be high, and the schematic is attached.
Here's my operation flow and a weird situation is observed:
1. Complete system power-off and power-on
2. Read the PCA9500 I/O port register -> OK
3. Read the PCA9500 EEPROM register -> OK
4. Write the PCA9500 EEPROM register -> OK
5. MCU reset
6. Read the PCA9500 I/O port register -> OK
7. Read the PCA9500 EEPROM register -> NACK fail. The screen shot of the logic analyzer is attached

It seems that the EEPROM interface of PCA9500 stop working after the MCU resets.
And it would not come back until the next hole system power on reset.
But the I/O port register stays working.
Is there any suggestion?

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