LEDs and buttons on STM32 MPU boards

Applicable for

STM32MP13x lines, STM32MP15x lines

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1 Introduction

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

2 Description

2.1 LEDs

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

2.2 Buttons

Button label	Purpose
WAKE UP	Allows the platform to be woken from any low-power mode
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 

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 

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).