RESETBMCU pull up resistor

[atillametetured]

Hello,

On SPF-27392_C5 page 19 (Sabre for Smart Devices) PMIC Control block, at RESETBMCU is connected directly to POR_B of i.MX6Q. Datasheet for PF0100 says RESETBMCU is an ope-drain output and is asserted low after a turn on event for a given time.

If this is an open drain output which asserts low after a turn on event, shouldnt it be pulled high to VSNVS first and then connected to POR_B?

Best Regards,

Mete

[art · Accepted solution]

The POR_B pad of i.MX6Q has the internal 100kOhm pull-up resistor, that is used here for the reset circuit.

Have a great day,
Artur

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[dharitrihazarik]

Hi Artur,

We are using MIPI 10 pin JTAG connector which has only TRST pin and no SRST. How would the system reset occur without SRST and should TRST be connected to POR_B pin of processor for system reset.

Regards,

Dharitri

[art]

The TRST signal is only meant to reset the JTAG state machine, not the whole system. So, without SRST signal, seems that you have to perform the whole system reset manually, as required.

Best Regards,

Artur

[dharitrihazarik]

Thanks for the response Artur. I have one more doubt.

I am confused with the jtag connector connections;

In lauterbach guide the connections are given as below:

But in Sabre (ref schematics), they have connected it as below:

Can you please clarify regarding the 9th Pin connection? Does it has to be connected to TRST or should it be grounded?

Thanks,

Dharitri

[art]

If R765 is not populated (as marked on the schematic above), the connector of your JTAG probe can remain unchanged.

Artur