Difference of JTAG communication failure between with external pull-up and without

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JuIn_1625121
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The customer has two boards that they have S6E2C1AH0AGV2000A.

One of them has external pull-up for JTAG.

The other one doesn't has external pull-up.

I thought that there is no difference of JTAG communication failure because there are internal pull-up,

but the board having external pull-up is less communication failure than no pull-up.

Is this phenomenon correct?

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GeonaP_26
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250 solutions authored 100 solutions authored 50 solutions authored

Hello Inoue-San,

Yes, your understanding on internal pull up is correct. JTAG has internal pull up. As the total pull up resistor value may not be suitable for JTAG communication, it is recommended to avoid external pull up at JTAG pins.

Can you please elaborate on the communication failures? How are you debugging? What is the external pull up value?

Best Regards,

Geon

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GeonaP_26
Moderator
Moderator
Moderator
250 solutions authored 100 solutions authored 50 solutions authored

Hello Inoue-San,

Yes, your understanding on internal pull up is correct. JTAG has internal pull up. As the total pull up resistor value may not be suitable for JTAG communication, it is recommended to avoid external pull up at JTAG pins.

Can you please elaborate on the communication failures? How are you debugging? What is the external pull up value?

Best Regards,

Geon

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