Technical Support

priyadarshini_m — Tue, 16 Mar 2021 08:38:43 GMT

Kindly clarify power on reset for IMX8M Mini application processor.. When I press the reset button, then how much time delay needed so that the power on reset pin will detect the signal and get enabled?

Re: Technical Support

Yuri — Tue, 16 Mar 2021 10:09:26 GMT

@priyadarshini_m
Hello,

From i.MX 8M Mini LPDDR4 EVKB Board Hardware User's Guide( Rev. 0, February 18, 2021):

2.19 (User interface buttons)

There are two user interface buttons on the EVKB board.

2.19.1 [Power button (SW901)]

The i.MX 8M Mini Applications Processor supports the use of a button input signal to request main SoC power state changes (i.e. ON or OFF) from the PMU.
The ON/OFF button can be used for debounce, OFF-to-ON time, and max timeout. Debounce is used to generate the power-off interrupt. In the ON state, if the ON/OFF button is held longer than the debounce time, the power-off interrupt is generated. In the OFF state, if the ON/OFF button is held longer than the OFF-to-ON time, the state will transit from OFF to ON. Max timeout can also be the time for requesting physical power down after the ON/OFF button has been held for the defined time.

2.19.2 [Reset button (SW902)]

The RESET button (SW902) is directly connected to the PMIC PCA9450A. Holding the RESET button will force to reset the PMIC power outputs except NVCC_SNVS_1V8 and VDD_SNVS_0V8 on the EVKB board. The i.MX 8M Mini applications processor will be immediately turned off and reinitiate a boot cycle from the OFF state.

< https://www.nxp.com/docs/en/user-guide/IMX8MMEVKBHUG.pdf >

According to Hardware Development Guide for the i.MX8Mm:

For portable applications, the ONOFF pin may be connected to an ON/OFF SPST push-button switch to ground. An external pull-up resistor is required on this pin.

A brief connection to GND in OFF mode causes the internal power management state machine to change state to ON. In ON mode, a brief connection to GND generates an interrupt (intended to initiate a software-controllable power-down). The connection to GND for approximate 5 seconds or more causes a forced OFF.

< https://www.nxp.com/docs/en/user-guide/IMX8MMHDG.pdf >

Regards,
Yuri.

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