查看“LEDs and buttons on STM32 MPU boards”的源代码

== Introduction ==
STM32 MPU Evaluation boards and Discovery kits share the same usage for LEDs and buttons. The following paragraphs describe the functional mapping of the LEDs and buttons, so that you can refer to the respective board-hardware descriptions to determine to which GPIO each function is mapped:
* [[STM32MP157x-EV1_-_hardware_description#User_buttons_and_LEDs|STM32MP157x-EV1 - hardware description]] for the Evaluation boards
* [[STM32MP157x-DKx_-_hardware_description#User_buttons_and_LEDs|STM32MP157x-DKx - hardware description]] for the Discovery kits.

== Description ==
{|
! LED color
! Button label
! Purpose
|-
| -
| WAKE UP
| This '''button''' allows the platform to be woken from any low-power mode<ref>[[Power overview]]</ref>
|-
| <span style="color: green;">Green</span><br />(*)
| USER1<br />(*)
| This can be used at boot time as a '''button''', by [[U-Boot overview|U-Boot]], to enter USB programming mode with [[STM32CubeProgrammer]]. This avoids manipulation of the [[STM32MP15_ROM_code_overview#Boot device selection via the boot pins and OTP|boot pins]] when a valid U-Boot image is already present in the board.<br />
It can be used at runtime as:<br />
* a '''LED''' or a '''button''' for Linux examples
* a '''button''' for STM32Cube examples
|-
| <span style="color: red;">Red</span><br />(*)
| USER2<br />(*)
| This can be used at boot time as a '''button''', by [[U-Boot overview|U-Boot]], to enter  [[STM32MPU distribution for Android|Android]] Fastboot mode.<br />
It is also used as a '''LED''' to show Cortex-A boot information<ref name="boot info">[[How to diagnose a boot failure]]</ref>, then it can be used, at runtime, as a '''button''' for Linux examples. It is not used by STM32Cube.<br />
|-
| <span style="color: blue;">Blue</span>
| -
| Linux heartbeat '''LED''', which blinks as long as the Linux<ref>[[STM32MP15 Linux kernel overview]]</ref> is alive<ref name="boot info"/> on the Cortex-A
|-
| <span style="color: orange;">Orange</span>
| -
| STM32Cube<ref>[[STM32CubeMP1 architecture]]</ref> examples verdict '''LED'''.
|-
|}
{{Warning| (*) Both a LED and a button are 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).}}

== References ==
<references />