Serial LTE Modem app in NCS main - glitch on TX after RESET

Hi,

This is normal.

After a reset, all GPIOs are in reset-state, meaning that the pins will float.

What you're seeing is the time from CPU starts executing the first instruction, to the time it takes before the NRF_UARTE peripheral is configured.

To avoid this, I would recommend to consider using an external pull-up on the line(s) in question.

Kind regards,

Håkon

Hi,

This is normal.

After a reset, all GPIOs are in reset-state, meaning that the pins will float.

What you're seeing is the time from CPU starts executing the first instruction, to the time it takes before the NRF_UARTE peripheral is configured.

To avoid this, I would recommend to consider using an external pull-up on the line(s) in question.

Kind regards,

Håkon

Hi,

that is not normal, is is exactly same with 10k pull-up.

There should not be any Low level glitch on UART2 TX (used for SLM AT commands).

Regards,
Michal

Hi,

If I do not add an external pull, I see a similar ~1.1 ms low-period:

If I add a external pull up, I do not see this low period:

Kind regards,

Håkon

Hi,

I am sorry, I applied pull-up to wrong ping. I see same results as you now.

But with pull-up on UART2 TX, nRF9160 sustained power consuption after RESET increased from ~7uA to ~15uA.

Do you have any explanation for that please ?

Thank you.

Regards,

Michal

Hi Michal,

This seems to correlate more towards your other case:

https://devzone.nordicsemi.com/f/nordic-q-a/88108/serial-lte-modem-app-in-ncs-main-has-unexpected-power-consumption-after-xsleep-2

michalm said:

But with pull-up on UART2 TX, nRF9160 sustained power consuption after RESET increased from ~7uA to ~15uA.

Do you have any explanation for that please ?

As mentioned, I do not see any of these issues on my end when testing with your provided configurations. Could you share more details about your setup (any changes to the board, external sensors etc.)?

Kind regards,

Håkon

Hi Håkon,

sure, I described test setup in https://docs.google.com/document/d/1HuWBlC9k0IS1NcfX7aGUEJqAxwaqZV2D8SHFDCM0CXs/edit?usp=sharing

Regards,
Michal