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Original question:

TCA9544A: Problem with channel selection

TCA9544A: MUX Output Problem

Robert Benedikt
Prodigy 90 points
Part Number: TCA9544A
Other Parts Discussed in Thread: TCA9536,

Hello

I´m trying to start some I2C communication with some preasure sensors.

On the I2C bus there are 3 participants.

  • TCA9536 (Addr: 0x41) - to switch on/off power for sensor - communication is OK
  • TCA9544A (Addr: 0x70 - Mux for I2C protocolls. Communcation with TCA9544A seams OK because I get an ACK on the I2C bus.
  • Some Preasure Sensors..

If you look at my oscilloscope screen shots, I to not understand where there is the problem.

So do you have any advice for me.

Thanks RobertI2C_Problem_TCA954A.pdf

  • 0
    TI__Guru 60850 points

    Hey Robert,

    Our I2C switches require a stop condition (SCL and SDA are low and then SCL goes high and then SDA goes high after a brief time), can you try to initiate a proper stop condition and then see if channel 0 gets enabled properly? Right now it looks like the data line goes high before the clock line which is an invalid stop condition. If you still have problems after doing a valid stop condition, let me know.

    Also can you post a schematic of our I2C device? I'd like to double check to make sure everything looks okay.

    Thanks,

    -Bobby