my board use poweroff and it reboot

[Xxiao.3]

my board have not use pmic and i use poweroff close the board. it will reboot and tf-a report reset reason (0x814) for NRST

[Xxiao.3]

[PatrickF]

Hi,

If you expect to poweroff the supplies, I think you have provisioned some external HW for that (to power off and able to power on again with e.g. a button or a request from RTC/TAMP). Which interface you have for that (I2C, GPIOs, ?)

I think TF-A should be adapted to your HW.

Regards.

Patrick

[Xxiao.3]

i have two version hw. ver.1 can use poweroff to close, but ver.2 can't both have same power support. ver.2 use poweroff and it will be go into bor_rst and reset the board.

[PatrickF]

Hi,

When you shutdown supplies including VDD, it is normal behavior to get a NRST=0 when VDD became too low. This cannot be avoided.

For example, if you use a GPIO output to start an HW shutdown to your supplies, the NRST=0 will put back all GPIOs to high-z which might put the power supplies back to ON state.

It is up to your board HW to ignore this and continue the HW shutdown sequence until complete platform power-off.

it is usually tricky to have such power on/off HW mechanism reliable. STPMIC1 is more handy for doing this.

Regards.