Last edited 3 months ago

LEDs and buttons on STM32 MPU boards

Applicable for STM32MP13x lines, STM32MP15x lines, STM32MP25x 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][4] examples verdict, on STM32MP15 and STM32MP25. 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[5]
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. Used at runtime for Linux on STM32MP25.

USER2
Used at boot time by U-Boot to enter Android Fastboot mode. Not yet supported on STM32MP25

Used at runtime for Linux, on STM32MP13.
Can be used at runtime for STM32Cube examples on STM32MP25.

TAMPER Allows to generate an external tamper event. Only present on STM32MP13 board and STM32MP25 board.

3. On STM32MP13x lines More info.png[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 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 source]

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. On STM32MP25x lines More info.png[edit source]

On STM32MP257F-EV1 Evaluation board More info green.png, the GPIO assignment is as follow:


GPIO for LEDs
LED color and label GPIO
Green LD3 PJ6
Red LD1 PH4
Orange LD2 PD8
Blue LED1 PJ7
GPIO for user buttons
Button GPIO
USER1 PD2
USER2 PG8

6. References[edit source]