i.MX6 POR_B pin behaviour

[ndsonu]

Hello All,

We have a custom board based on i.MX6 ( Quad core version) and we are running linux on it.

The board is booting from emmC.

The POR_B pin of i.MX6 is connected to the RESETB_MCU pin of PMIC ( PF0100).

I tried to reset the i.MX6 on the board by explicitly pulling the POR_B pin to GND ( I soldered a wire out from this pin).

If I am in uboot and reset the processor , it will get reset and will reboot.

But after booting completely,  that is , once we get the linux prompt, if I reset the processor , it is not rebooting.

Can somebody help me to know why is this so?

Is it because Linux configures the core voltages to a low voltage ?

Thank you!

Regards,

Sonu

[igorpadykov · Accepted solution]

Hi Sonu

such behaviour may be caused by fact that

linux controls (changes) PMIC voltages. So one needs

to reset both PMIC (with PWRON signal) and i.MX6.

For example in Sabre schematic WDOG resets whole board using PWRON:

SPF-27392 i.MX6_SABRE_SDP_DESIGNFILES

Best regards

igor

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[ndsonu]

Hello Igor,

Thanks a lot for the reply.

I understand that now.

This brings me to another question.

If I feed the 'Watch dog reset out' to PMIC Power ON, will I be able to identify the boot reason as "WDOG" from some registers?

[Looks like if watchdog hits PMIC will assert the POR_B of i.MX6 low.Once POR_B is assreted and released i.MX6 will consider as a Power On Reset only.]

Thanks,

Sonu