Based on the example USB HID keyboard https://developer.mbed.org/users/jbru/code/BLE_HID_KeyboardStreamDemo/

Dependencies:   BLE_API mbed nRF51822

Fork of HID-kb by Microbug

Revision:
1:9e174f8fd9e9
Parent:
0:cb1939018833
--- a/BLE_API.lib	Mon Nov 02 18:25:58 2015 +0000
+++ b/BLE_API.lib	Wed Aug 31 18:59:58 2016 +0000
@@ -1,1 +1,1 @@
-http://mbed.org/teams/Bluetooth-Low-Energy/code/BLE_API/#d494ad3e87bd
+http://mbed.org/teams/Bluetooth-Low-Energy/code/BLE_API/#ff83f0020480