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Interfacing multiple P82B96 buffers

James Holmes77291
Prodigy 40 points
Other Parts Discussed in Thread: P82B96, TCA9509, P82B715

Hi,

I am trying to interface two existing systems both based around the P82B96 buffer device. One system provides access to its I2C bus only via the Sx and Sy pins of a P82B96 and I wish to interface this over a cable run to a second device which interfaces via the RxTx/RyTx pins of its own P82B96, as below:

Logically, the remote peripheral would be connected via the RxTx/RyTx pins of an additional P82B96, but this would require connecting the Sx/Sy pins of the new buffer back to back with the buffer in the established architecture which is not permitted due to the buffered low signal generated by the IC.

Could, for example, the TCA9509 be used between these two systems to provide a buffered connection to the remote peripheral and maintain compatibility with the P82B96 Sx/Sy pins? Or is there an alternative buffer/repeater which will work in this situation?

Any advice is appreciated. Best regards,

James.

  • 0
    Prodigy 40 points

    Anyone any ideas on this?

  • 0 in reply to James Holmes77291
    Prodigy 10 points

    There are some new Fast-mode Plus bus buffers that don't have static or dynamic offset but use the score board method for directional control (called No Offset bus buffers).

    The PCA9605 is high drive like the P82B96 but also operates at 1 MHz. The PCA9605 can be used on the remote card.

    In order to work to provide bidirectional signanling without the direction pin the No Offset bus buffer clock is unidirectional and there is a glitch (screened out by mandatory noise filter) as the data line switches.

    You can also use the P82B715 amplifier back to back so you don't have the offset problem but need to include the main bus and remote bus in loading/pull up resistor calculations.