i.MX8QM reset

[st_hw]

Hi,

I am currently using i.MX8QM for a circuit design. Encountered an issue: If the POR_B pin of i.MX8QM could be connected to signals other than the RESETBMCU pin of PMIC, such as external buttons. In other words, if the POR_B pin of i.MX8QM could be used as a non power-off reset pin, except for power on reset. That is, the power of i.MX8QM is maintained normally, while internal reset occurs in IMX8QM.

[JorgeCas]

Hello, I hope you are doing well.

From your description I understood that i.MX8QM reset could be activated from different sources but, I do not totally understand your question. Could you please explain me a little bit more?

Best regards.

[st_hw]

Hi，

Thanks very much for attention.

My question is to confirm if the i.MX8QM has multiple hardware reset methods. Based on my study on the circuit diagram of the i.MX 8QM CPU Card, the POR_B of the i.MX8QM only receives reset signal from PMIC.

However, I want to use an additional reset signal (not the reset signal from PMIC) to reset the i.MX8QM separately. I don't know if this solution is feasible and if it will damage the i.MX8QM chip.

According to my reset plan, I will firstly perform logical AND on the two reset signals mentioned above , and then output the result of logical AND to i.MX8QM. So, there will be two reset cases to reset i MX8QM.
The first is WD abnormality, which causes PMIC to enter WD event. PMIC will set RESETBMCU to low level and then reset i.MX8QM. At the same time, the Regulator outputs of PMIC will enter the default OTP configuration. The i.MX8QM will enter to Power On Reset.
The second is to manually reset the i.MX8QM. When I was debugging i.MX8QM, I had a requirement to reset IMX8, but I didn't want to reset i.MX8QM through PMIC. So, I set the additional reset signal to a low level to reset IMX8. In this reset situation, the Regulator output of PMIC will remain and will not enter to default OTP configuration.

I don't know if I have explained the problem clearl. And I am not sure if my second reset method is feasible, and I hope to receive your help.

[JorgeCas]

Hello,

I think your reset design should be feasible. If you are worried about damage your MPU, just keep the power-up/power-down sequence and you should be safe.

Bes regards.