平台：瑞芯的rk3288

作者：fulinux

*****本文允许转载，不过请注明出处：http://blog.csdn.net/fulinus****

1、硬件环境

任意选取一个GPIO引脚作为heartbeat的输出，选择一个未被使用的SPI0_CSn0，如底板原理图所示：

对应在顶板上连接rk3288的是GPIO5 _ B5 _ u引脚，如图：

2、软件环境

在kernel/arch/arm/boot/dts/rk3288-tb_8846.dts文件中配置如下：

diff --git a/arch/arm/boot/dts/rk3288-tb_8846.dts b/arch/arm/boot/dts/rk3288-tb_8846.dts
index c92d973..91ad1da 100644
--- a/arch/arm/boot/dts/rk3288-tb_8846.dts
+++ b/arch/arm/boot/dts/rk3288-tb_8846.dts
@@ -6,6 +6,16 @@
 #include "vtl_ts_sdk8846.dtsi"

 / {
+    leds {
+        compatible = "gpio-leds";
+        led0 {
+            label = "led0";
+            gpios = <&gpio5 GPIO_B5 GPIO_ACTIVE_HIGH>;
+            linux,default-trigger = "heartbeat";
+            default-state = "off";
+        };
+    };
+
        fiq-debugger {
                status = "okay";
        };

内核配置如下：

--- LED Support

<*>   LED Support for GPIO connected LEDs

[*]   LED Trigger support  --->

<*>   LED Heartbeat Trigger

正常编译后烧录到开发板上，通过示波器可以看到心跳波形：