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Original question:

AM6442: how is "Boundary Scan" accessed?

AM6442: Boundary scan chain breaks or not ?

Thierry HAUSER
Intellectual 400 points
Other Parts Discussed in Thread: AM6442

Tool/software:

Hello,

We are using AM6442, and some interfaces are not used , like MMC0 or MMC1 or SERDES. No traces are connected to these unused interfaces.

We plan to use JTAG BSDL for others GPIOs of AM64.

According this thread : 

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1082475/am6442-how-is-boundary-scan-accessed?tisearch=e2e-sitesearch&keymatch=AM6442%20boundary#

I understood, that it's mandatory to power the SERDES, even if unused, just to not break the BSDL chain.

Is it also the same for others unused interfaces ?

Thanks for your help.

  • 0
    TI__Guru**** 192369 points

    Hello Thierry HAUSER

    Thank you for the query.

    Thierry HAUSER said:
    Is it also the same for others unused interfaces ?

    Can you please add some examples on what you mean by interfaces 

    SERDES0 here means either PCIe or USB3 interface 

    Refer Table 5-80. Connectivity Requirements (continued) page 94

    P13
    P11
    R14
    VDDA_0P85_SERDES0
    VDDA_0P85_SERDES0
    VDDA_0P85_SERDES0_C
    VDDA_1P8_SERDES0
    If SERDES0 is not used and the device boundary scan function is required,
    each of these balls must be connected to valid power sources.
    If SERDES0 is not used and the device boundary scan function is not required,
    each of these balls can alternatively be connected directly to VSS.

    SERDES0 is the only peripheral that has the requirements related to boundary scan for AM64x.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    Intellectual 400 points

    Hello  

    So SERDES0 is the only peripheral which need to be powered to not break the BSDL chain ?

    If other unused peripheral like MMC0, implies to have VDDA_3P3_SDIO connected to VSS, and this will not break the BSDL chain, isn't it?

    Thanks for your help.

  • 0 in reply to Thierry HAUSER
    TI__Guru**** 192369 points

    Hello Thierry HAUSER

    Thank you.

    MMC0 is for eMMC and the pin connectivity requirements is for a valid suppy to be connected.

    VDDA_3P3_SDIO  is intended to generate the IO supply for SD card connected on the MMC1 interface,

    Thierry HAUSER said:
    VDDA_3P3_SDIO connected to VSS

    This is enabling the LDO.

    The VDDSHV1 SDIO supply when SD card is not used or UHS-I speed is not used is expected to be connected to a fixed 3.3V or 1.8V IO.

    Thierry HAUSER said:
    So SERDES0 is the only peripheral which need to be powered to not break the BSDL chain ?

    The pin connectivity requirements allows SERDES0 to be disabled to save power and hence the recommendation to power the peripheral in case boundary scan is used.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    TI__Guru**** 192369 points

    Hello Thierry HAUSER

    There is another peripheral USB2 that has power supply connection requirements in the [pin connectivity table.

    I suspect it is OK to ground the supplies in case USB2 is not used since the USB2 signals are not included in the BSDL file.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    Intellectual 400 points

    Hello  

    It's not clear at all for me.

    Let's summarize :

    we don't use  MMC0+MMC1+SERDES+ADC, others VDDSHVx banks are used.

    What should I do in term of bank powering to allow BSDL to work fine for used interface , without broken chain for unused interfaces?

  • 0 in reply to Thierry HAUSER
    TI__Guru**** 192369 points

    Hello Thierry HAUSER

    SERDES0 not used 

    Has 2 cases, when boundary scan is used and boundary scan is not used 

    Table 5-80. Connectivity Requirements

    ADC0 not used 

    Table 5-80. Connectivity Requirements

    MMC0 not used  (MMC0 is a hard phy implementation)

    Table 5-80. Connectivity Requirements

    MMC1 (SD card note used)

    LDO connection

    Table 5-80. Connectivity Requirements

    VDDSHV5

    Connect to a valid IO supply 1.8V or 3.3V based on the IO usage.

    The SDIO buffer supports configuring alternate muxed function

    Table 5-1. Pin Attributes (ALV Package)

    I have shown the data signals

    Same is true for CMD, SDCD and SDWP

    I hope this is clear now.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    TI__Guru**** 192369 points

    Hello Thierry HAUSER

    Did you have any additional queries or can we close the thread.

    Regards,

    Sreenivasa