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Original question:

PCA9534: Silicon and Documentation Issue

PCA9534: GPIO4 to GPIO8 cannot be controlled

Lumina Gui
Genius 3610 points
Part Number: PCA9534

Dear TI Teams,

We found that only GPIOI to GPIO3 can be controlled during debugging PCA9534RGVR，while the GPIO4 to GPIO cannot be controlled. After analysis, it was found that only the low three bits can be changed when reading and writing registers in Table 9-3, and the high five bits cannot be changed.

 Writing 0xFF to Configuration Register, but the read value is 0x07, and the reading value is 0x05 when wiring is 0X35. We used an I2C logic analyzer to capture the log information and found that SMBus communication is normal. 

The SMBus protocol is ReadByte and WriteByte. Can you help to analyze the cause of the problem?

Write 0xFF to Configuration Register.

Read Configuration Register.

Write 0x35 to Configuration Register.

Read Configuration Register.

Thanks,

Kind Regards

  • 0
    TI__Mastermind 39986 points

    Hey Lumina,

    Could you provide a schematic of the device on how it is currently setup? If possible please also capture the R/W operations with an oscilloscope instead, as logic analyzers may not capture the full scope of details of the signals. 

    Regards,

    Jack 

  • 0 in reply to Jack Guan
    Genius 3610 points

    Hi Jack,

    Pls check the below schematic:

    SMBUS to GPIO.pdf

    The data captured by the oscilloscope is as follows:

    Write 0x35 to Configuration Register,

    Read Configuration Register,

    Thanks,

    Kind Regards

  • 0 in reply to Lumina Gui
    TI__Mastermind 39986 points

    Hey Lumina,

    Thanks for sending the updated waveforms and schematic. Can this trend also be seen when attempting to read/ write other data bytes as well? It seems that P4~P8 are not reading back the correct data for address 0xFF sent, but for 0x35 sent, only P5 and P4 are wrong.

    How many devices has this impacted (is there a possibility that it is one unit that is damaged)?