Use the microbit as a foot paddle Send Shift-Ctrl-Alt F11 and F12 for the buttons, you can use those a global hotkeys for actions, e.g. mute/unmute microphone

Dependencies:   mbed BLE_API nRF51822

Revision:
4:c7384b889baa
Parent:
3:7d7822143a2d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Apr 08 22:13:34 2019 +0000
@@ -0,0 +1,150 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2015 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mbed.h"
+
+#include "ble/BLE.h"
+#include "KeyboardService.h"
+
+#include "examples_common.h"
+
+/**
+ * This program implements a complete HID-over-Gatt Profile:
+ *  - HID is provided by KeyboardService
+ *  - Battery Service
+ *  - Device Information Service
+ *
+ * Complete strings can be sent over BLE using printf. Please note, however, than a 12char string
+ * will take about 500ms to transmit, principally because of the limited notification rate in BLE.
+ * KeyboardService uses a circular buffer to store the strings to send, and calls to putc will fail
+ * once this buffer is full. This will result in partial strings being sent to the client.
+ */
+ 
+ //The micro:bit has a matrixed display, this is a simple way to use some LEDs on it
+DigitalOut col9(P0_12, 0);
+
+DigitalOut waiting_led(P0_13);
+DigitalOut connected_led(P0_15);
+
+InterruptIn button1(BUTTON_A);
+InterruptIn button2(BUTTON_B);
+
+BLE ble;
+KeyboardService *kbdServicePtr;
+
+static const char DEVICE_NAME[] = "micro:bit Foot Paddle";
+static const char SHORT_DEVICE_NAME[] = "footpaddle";
+
+static void onDisconnect(const Gap::DisconnectionCallbackParams_t *params)
+{
+    HID_DEBUG("disconnected\r\n");
+    connected_led = 0;
+
+    ble.gap().startAdvertising(); // restart advertising
+}
+
+static void onConnect(const Gap::ConnectionCallbackParams_t *params)
+{
+    HID_DEBUG("connected\r\n");
+    waiting_led = false;
+}
+
+static void waiting() {
+    if (!kbdServicePtr->isConnected())
+        waiting_led = !waiting_led;
+    else
+        connected_led = !connected_led;
+}
+
+void send_string(const char * c) {
+    if (!kbdServicePtr)
+        return;
+
+    if (!kbdServicePtr->isConnected()) {
+        HID_DEBUG("we haven't connected yet...");
+    } else {
+        int len = strlen(c);
+        kbdServicePtr->printf(c);
+        HID_DEBUG("sending %d chars: %s\r\n", len, c);
+    }
+}
+
+void send_ctrl_shift_alt(const uint8_t key) {
+    if (!kbdServicePtr)
+        return;
+
+    if (!kbdServicePtr->isConnected()) {
+        HID_DEBUG("we haven't connected yet...");
+    } else {
+        kbdServicePtr->keyDownCode(key, KEY_CTRL + KEY_SHIFT + KEY_ALT);
+        HID_DEBUG("sending 0x%X\r\n", key);
+        kbdServicePtr->keyUpCode();
+    }
+}
+void pressed_button1() {
+    send_ctrl_shift_alt(0x8A);
+    wait(0.1);
+
+}
+
+void pressed_button2() {
+    send_ctrl_shift_alt(0x8B);
+    wait(0.1);
+
+}
+
+int main()
+{
+    Ticker heartbeat;
+
+    button1.rise(pressed_button1);
+    button2.rise(pressed_button2);
+
+    HID_DEBUG("initialising ticker\r\n");
+
+    heartbeat.attach(waiting, 1);
+
+    HID_DEBUG("initialising ble\r\n");
+    ble.init();
+
+    ble.gap().onDisconnection(onDisconnect);
+    ble.gap().onConnection(onConnect);
+
+    initializeSecurity(ble);
+
+    HID_DEBUG("adding hid service\r\n");
+    KeyboardService kbdService(ble);
+    kbdServicePtr = &kbdService;
+
+    HID_DEBUG("adding device info and battery service\r\n");
+    initializeHOGP(ble);
+
+    HID_DEBUG("setting up gap\r\n");
+    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::KEYBOARD);
+    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME,
+                                           (uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME));
+    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::SHORTENED_LOCAL_NAME,
+                                           (uint8_t *)SHORT_DEVICE_NAME, sizeof(SHORT_DEVICE_NAME));
+    ble.gap().setDeviceName((const uint8_t *)DEVICE_NAME);
+
+    HID_DEBUG("advertising\r\n");
+    ble.gap().startAdvertising();
+
+    while (true) {
+        ble.waitForEvent();
+    }
+}
+