LEDs and buttons on STM32 MPU boards

Applicable for STM32MP13x lines, STM32MP15x lines

1 Introduction[edit]

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

2 Description[edit]

2.1 LEDs[edit]

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]

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 boot pins 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 Warning.png[edit]

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 white.png 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 More info.png[edit]

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

Warning white.png 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]