Power Supply, Reset and Boot mode

Pin Signal Description type I/O
49,50 VIN Module power supply input power I
51 NRST_PWREN Reset and Peripheral Power Enable 1V8/3V3 OD I/O
52 BOOTMODE Boot Mode Select 3V3 I

Power Supply

QS modules operate with a single 3.3V power supply, while QSX modules can also be powered from higher voltages up to 5V nominal. All other voltages are handled onboard so there is no need to care about such things on the baseboard. Nevertheless, pay attention to the absolute maximum ratings of directly connected processor pins during power-up and as long as no power is provided.

QS Operating conditions

Parameter Description Min Typ Max
VIN Power Supply Voltage 3.1V 3.3V 3.6V

QSX Operating conditions

Parameter Description Min Typ Max
VIN Power Supply Voltage 3.1V 3.3 to 5V 5.5V

NRST_PWREN - Reset and Peripheral Power Enable

This dual function pin is used as reset input and peripheral power supply enable output. Depending on the QS module the function is slightly different.

The example below uses a load switch. 3V3QS is a main power supply connected to 3V3_IN of the QS module and 3V3 is used for the peripherals on the baseboard.

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QSMP

3.3V NRST_PWREN is directly connected to STM32MP1 NRST and NRST_CORE and enables the DDR memory power supply VDD_DDR. 10nF capacitors on NRST and NRST_CORE protects the device against parasitic resets.

The STM32MP1 has permanent internal pull-up resistors to 3.3V. Refer also to page 174, chap. 6.3.18 NRST and NRST_CORE pin characteristics:

QS8M

1.8V NRST_PWREN is directly connected to i.MX8M POR_B (1.8V level) and PMIC RESETO. RN6T567 RESETO is an open drain host reset output. RESETO is pulled low during power-on and power-off sequences and is released after the power-on sequence has finished and all supplies are valid.

A 10K pull-up to 1.8V is used onboard.

QSX

1.8V NRST_PWREN is directly connected to PCA9450 PMIC_RST_B (1.8V level).

A 10K pull-up to 1.8V is used onboard.

BOOTMODE

System Boot Mode Select - The operational system boot mode of the module upon system reset is determined by the settings of this pin. This can be either boot from Flash or boot from USB. The default state is boot from Flash. Leave unconnected if no used.

The polarity depends on the QS module:

BOOTMODE DEFAULT BOOT FROM FLASH BOOT FROM USB
QSMP pull-up 1 0
QS8M pull-down 0 1
QSXM,QSXP pull-down 0 1

QS Standard Contact Group Index

Pins Funktion Pins Funktion Pins Funktion Pins Funktion
1-4 SPI 5-10 I2C 11-14 CAN 15-18 SAI
19-35 Ethernet 36-42 SD Interface 43-48 USB 49-52 Power Supply, Reset and Boot mode
53-76 18-bit RGB Display Interface 77-78 Backlight and Display Control 53-72 Camera 79-88 MIPI DSI Display
89-96 UART 97-100 SPI 1A,75A,76A,100A PCIe 25A,26A,50A,51A USB3 Super Speed