added an LED that turns on when the wrist is zeroed
diff --git a/bbb_cape/src/bbb/led.h b/bbb_cape/src/bbb/led.h
new file mode 100644
index 0000000..19976e6
--- /dev/null
+++ b/bbb_cape/src/bbb/led.h
@@ -0,0 +1,27 @@
+#ifndef BBB_CAPE_SRC_BBB_LED_H_
+#define BBB_CAPE_SRC_BBB_LED_H_
+
+#include <stdio.h>
+
+#include "aos/common/macros.h"
+
+namespace bbb {
+
+// Allows easily controlling one of the LEDs.
+class LED {
+ public:
+ LED(int number);
+ ~LED();
+
+ void Set(bool on);
+
+ private:
+ FILE *brightness_handle_ = nullptr;
+ const int number_;
+
+ DISALLOW_COPY_AND_ASSIGN(LED);
+};
+
+} // namespace bbb
+
+#endif // BBB_CAPE_SRC_BBB_LED_H_