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TMS320LF2407A: Boundary scan?

Gregory Duperon
Expert 7680 points
Part Number: TMS320LF2407A


The datasheet states “The x240xA DSPs do not include boundary scan. The scan chain of these devices is useful for emulation function only.”

Does this mean that Boundary Scan testing of downstream devices in the JTAG chain can’t be done through the tms320lf2407a JTAG interface?

Since it does not support boundary scan, I guess it would need a bypass mode in order to do this. Does it have this bypass mode?

  • 0
    TI__Mastermind 27200 points

    When connected as part of a scan chain this device can be set to 'bypass' mode, allowing other devices to reside in series with it in a JTAG chain.

    You can perform boundary scan testing of downstream devices in the normal way, but on C24x devices the full internal boundary scan registers are not implemented and the JTAG port is simply used for emulation and programming. 

    Regards,

    Richard

  • 0 in reply to Richard Poley
    TI__Expert 7680 points

    Thanks, Richard.

    To clarify, does programming mean programming of internal memory or of downstream JTAG devices such as PLDs, etc.?

  • 0 in reply to Gregory Duperon
    TI__Mastermind 27200 points

    You're welcome.  I meant just programming the LF2407 flash using TI's tools.  For other devices on the scan chain you'd need tools from those vendors, and they would need to be configured to recognize the bypass device in the chain.

    Regards,

    Richard

  • 0 in reply to Richard Poley
    Intellectual 280 points

    Do we get the 2407A into bypass mode by using a "bypass" instruction or is there a way to force the 2407A into bypass mode some other way?

    Thanks, Don

  • 0 in reply to Donald DeFord
    TI__Mastermind 27200 points

    Don,

    Correct. You put the device in bypass mode by writing '11111111' to the JTAG configuration resister. The JTAG specification of the DSP is...

     - Instruction Register Length

         8 bits, only IEEE 1149.1 instruction supported is BYPASS

    - BYPASS instruction:

         11111111 (0xFF)

    - Instruction register capture pattern length:

         8 bits

    - Boundary Scan Length

         N/A

    - JTAG ID Code

         N/A

    Regards,

    Richard

  • 0 in reply to Richard Poley
    Intellectual 280 points

    Richard, Thanks for the info. We are working with Atmel on the ATMISP tool and it is not properly detecting the 2407A.

    They asked if I could ask you "what the default state is for the 1-bit Bypass register when the TI 2407A enters Bypass mode (right after shifting in the Bypass instruction opcode)."

    Don

  • 0 in reply to Donald DeFord
    TI__Mastermind 27200 points

    Don,

    I'm sorry for the delay getting back to you.  My colleagues and I have been through what information we have on this topic without finding anything relevant.  I think we have to be honest and say we don't know.  The product is pretty old and none of the designers are with TI now.  Truly regret we can't help further with this.

    Regards,

    Richard