ERRATA e6573 of K70

[puspamnayak]

Hi I was going through the ERRATA for k70 and found it is mentioned "e6573: JTAG: JTAG TDO function on the PTA2 disables the pull resistor".

It is adviced to connect Pull device on TDO pin.

Want to know as i am not using JTAG Reset i.e. JTAG_TRST pin of k70 so is it necessary to Pull TDO pin to high or low,

if yes then with what value of resistor shall i pull it high or low ?

Note: please mention if TDO pin has to be pulled high or low if at all pull is required

Please reply at earliest

Thanks and regards,

Puspam N

[jeremyzhou]

Hi Puspam,

Actually, I'm not very clearly with your question.

You mentioned that you didn' use the JTAG_TRST pin, was that mean you disable the JTAG_TRST function on PTA3 pin?

So I'd like to confirm that with you ASAP, then I can give you appropriate suggestion for you.

I'm looking forward to your reply.
Have a great day,
Ping

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[puspamnayak]

Hi Jeremyzhou,

Thanks for your response. I am not using JTAG_TRST i.e. JTAG RESET and yes it is disabled for now but yes if required then we will use that in future.

So from ERRATA what i understood is that if we are using JTAG_TRST then we need to use a pull-up or pull-down at TDO pin as workaround  so as to avoid increased power consumption.

And also i was referring to Tower board schematic of K70 (TWR-K70F120M-SCH) where there is no pull-up or pull-down at TDO pin so i got confused that if really any pull-up/down is required at TDO pin.  If it is required then it should be Pull-Up or Pull-Down and what shall be the value of resistor to be considered.

Request you to correct me if my understanding is wrong as per given data in ERRATA e6573 and suggest me accordingly at earliest

Thanks and Regards,

Puspam Nayak

[jeremyzhou]

Hi Puspam,

Thanks for your reply.

Yes, it's recommended to enable pull-up or pull-dow, or add an exteran pull device or external soruce to the pin when set up the PTA2 as a digital input and left unconnected in the circuit from the errata doc.

However in the TWR-K70F120, PTA2 should be supported to work in JTAG_TDO function and according the JTAG debug interface specification, it's not necessary to add an external resistor to the pin.
Have a great day,
Jeremy

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