LEDs and buttons on STM32 MPU boards

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Applicable for

STM32MP13x lines, STM32MP15x lines

1. Introduction[edit source]

The following paragraphs describe the functional mapping of the LEDs and buttons.

2. Description[edit source]

2.1. LEDs[edit source]

LED color	Purpose
Green	Can be used at runtime for Linux examples
Red	Used to show Cortex-A boot information^[1]
Blue	U-Boot entering / exit indication then Linux heartbeat, which blinks as long as Linux^[2] is alive^[1] on the Cortex-A
Orange	Used for STM32Cube^[3] examples verdict, on STM32MP15. Free for user on STM32MP13.

2.2. Buttons[edit source]

Button label	Purpose
WAKE UP	Allows the platform to be woken from any low-power mode^[4]
USER1	Used at boot time by U-Boot to enter USB programming mode with STM32CubeProgrammer. This avoids manipulation of the STM32 MPU ROM code overview#Boot device selection when a valid U-Boot image is already present in the board. Can be used at runtime for Linux examples or STM32Cube examples, on STM32MP15.
USER2	Used at boot time by U-Boot to enter Android Fastboot mode. Used at runtime for Linux, on STM32MP13.
TAMPER	Allows to generate an external tamper event. Only present on STM32MP13 board.

3. On STM32MP13x lines [edit source]

On STM32MP135F-DK Discovery kit, the GPIO assignment is as follow:

The green LED is on the IO expander pin GPB6
The red LED and USER2 button are on the pin PA13
The blue LED and USER1 button are on the pin PA14
The orange LED is on the IO expander pin GPB7

Warning

"Blue LED & USER1", "Red LED & USER2" are respectively connected to the same GPIO, with inverted logic for the LED control (so the LED is switched on when the GPIO output is set low).

4. On STM32MP15x lines [edit source]

You can refer to the respective board-hardware descriptions to determine to which GPIO each function is mapped:

STM32MP157x-EV1 - hardware description for the Evaluation boards
STM32MP157x-DKx - hardware description for the Discovery kits.

Warning

"Green LED & USER1", "Red LED & USER2" are respectively connected to the same GPIO, with inverted logic for the LED control (so the LED is switched on when the GPIO output is set low).

5. References[edit source]

[boot_info-1] 1.0 ^1.1 How to diagnose a boot failure

[2] STM32 MPU Linux kernel overview

[3] STM32CubeMP1 architecture

[4] Power overview

[1]

[2]

[3]

[4]