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SCANSTA101: Bypass Scansta 101

Jamie Lee
Prodigy 10 points
Part Number: SCANSTA101

Hi, 

I am looking into the Scansta 101 datasheet, and got curious about whether it is possible to directly control dot1_SM pins (such as TMS_SM or TCK_SM) via input dot1 pins (like TMS or TDI), which will be connected to the external JTAG header.

Without this kind of "bypass" mode, I think I may need to use an additional MUX logic, or disable the output pins (making them being in a tri-state) of Scansta101 by strobing OE pins high, am I correct?

Regards,

Jin

  • 0
    TI__Mastermind 29635 points
    Hi Jin,

    This is a legacy device for TI, so we have limited knowledge regarding the SCANSTA101. Based on reading the datasheet, I do not think there is a way to interface between the dot1_SM pins, which are the actual test pins for the master SCANSTA101, and the dot1 pins, which act as the test/debug interface for the SCANSTA101. These appear to be separate entities, and I expect the dot1 pins to behave independently from the SCANSTA101 operations, similar to how JTAG boundary scan functions for other devices.

    I agree that you will need some way of creating a switch or mux in order to remove the dot1_SM pins from being part of the JTAG chain. I believe that strobing OE high will achieve this effect.

    Regards,

    Michael