JTAG TRSTn pulldown and other JTAG pullups

The AM62x datasheet states (in section 6.4) that an external pulldown is required on the TRSTn line. Is this implemented on the module (if so, it might not be publicly documented), or the host board needs to add this pulldown?

What about the EMU0, EMU1, MCU_RESETz, RESET?REQz, TCK, TDI and TMS lines (next row in the same table in the datasheet)? According to the datasheet the internal pullups may be used, but is there any external pulls implemented on the module?

Replies (3)

RE: JTAG TRSTn pulldown and other JTAG pullups - Added by Michael Williamson over 1 year ago

Hello,

The SOM includes the following on the JTAG related lines:

4.7K Pulldown on TRSTn
4.7k Pullup to VDDSHV_MCU on the following lines:
- TCK
- TDI
- TMS
- EMU0
- EMU1

This is a snippet of the schematic on the SOM with the connections to the logical nets.

The MCU_RESETz and RESET_REQz and the PMIC_PBn signals are not pulled up or down on the SOM. You must pull them up / deassert them on your carrier board design.

You are correct in that we don't document this in the datasheet. We will add this information in the next revision. Thank you for the feedback.

I apologize for the confusion.

With regards,
Mike

JTAGConnections.png (28.1 KB) JTAGConnections.png

RE: JTAG TRSTn pulldown and other JTAG pullups - Added by Michael Williamson over 1 year ago

I corrected the last post. TDO is not pulled up or down on the SOM.

RE: JTAG TRSTn pulldown and other JTAG pullups - Added by Pal Szabo over 1 year ago

Thank you very much Mike, this clarifies the implemented pulls!

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