mbed-os-examples / Mbed OS mbed-os-example-ble-BatteryLevel

This example creates and updates a standard Battery Level service containing a single GATT characteristic. The battery service transmits a device's battery level in percentage, with 100% being a fully charged battery and 0% being a fully drained battery. The canonical source for this example lives at https://github.com/ARMmbed/mbed-os-example-ble/tree/master/BLE_BatteryLevel

This example creates and updates a standard Battery Level service containing a single GATT characteristic.

The battery service transmits a device's battery level in percentage, with 100% being a fully charged battery and 0% being a fully drained battery.

Although the sample application runs on a BLE device, it doesn't show the device's real battery level (because that changes very slowly and will make for a dull example). Instead, it transmits a fake battery level that starts at 50% (half charged). Every half second, it increments the battery level, going in single increments until reaching 100% (as if the battery is charging). It then drops down to 20% to start incrementing again.

Running the application

Requirements

The sample application can be seen on any BLE scanner on a smartphone. If you don't have a scanner on your phone, please install :

- nRF Master Control Panel for Android.

- LightBlue for iPhone.

Hardware requirements are in the main readme.

Building instructions

Building with mbed CLI

If you'd like to use mbed CLI to build this, then you should refer to the main readme. The instructions here relate to using the developer.mbed.org Online Compiler

In order to build this example in the mbed Online Compiler, first import the example using the ‘Import’ button on the right hand side.

Next, select a platform to build for. This must either be a platform that supports BLE, for example the NRF51-DK, or one of the following:

List of platforms supporting Bluetooth Low Energy

Or you must also add a piece of hardware and the supporting library that includes a Bluetooth Low Energy driver for that hardware, for example the K64F or NUCLEO_F401RE with the X-NUCLEO-IDB05A1

List of components supporting Bluetooth Low Energy.

Once you have selected your platform, compile the example and drag and drop the resulting binary onto your board.

For general instructions on using the mbed Online Compiler, please see the mbed Handbook

Checking for success

Note: Screens captures depicted below show what is expected from this example if the scanner used is nRF Master Control Panel version 4.0.5. If you encounter any difficulties consider trying another scanner or another version of nRF Master Control Panel. Alternative scanners may require reference to their manuals.

  • Build the application and install it on your board as explained in the building instructions.
  • Open the BLE scanner on your phone.
  • Start a scan.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-BatteryLevel/raw-file/a5ac4bf2e468/img/start_scan.png

figure 1 How to start scan using nRF Master Control Panel 4.0.5

  • Find your device; it should be named `BATTERY`.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-BatteryLevel/raw-file/a5ac4bf2e468/img/scan_result.png

figure 2 Scan results using nRF Master Control Panel 4.0.5

  • Establish a connection with your device.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-BatteryLevel/raw-file/a5ac4bf2e468/img/connection.png

figure 3 How to establish a connection using Master Control Panel 4.0.5

  • Discover the services and the characteristics on the device. The *Battery service* has the UUID 0x180F and includes the *Battery level* characteristic which has the UUID 0x2A19.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-BatteryLevel/raw-file/a5ac4bf2e468/img/discovery.png

figure 4 Representation of the Battery service using Master Control Panel 4.0.5

  • Register for the notifications sent by the *Battery level* characteristic.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-BatteryLevel/raw-file/a5ac4bf2e468/img/register_to_notifications.png

figure 5 How to register to notifications using Master Control Panel 4.0.5

  • You should see the battery level value change every half second. It begins at 50, goes up to 100 (in steps of 1), resets to 20 and so on.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-BatteryLevel/raw-file/a5ac4bf2e468/img/notifications.png

figure 6 Notifications view using Master Control Panel 4.0.5

If you can see the characteristic, and if its value is incrementing correctly, the application is working properly.

source/main.cpp@2:18b05b3173a8, 2016-07-28 (annotated)

Committer:
mbed_official
Date:
Thu Jul 28 23:14:21 2016 +0100
Revision:
2:18b05b3173a8
Parent:
0:8113e6c77cd7
Child:
3:488ecd009a27
Merge branch 'master' of https://github.com/ARMmbed/mbed-os-example-ble





Commit copied from ./src/github.com/ARMmbed/mbed-os-example-ble

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 2:18b05b3173a8 1 /* mbed Microcontroller Library
mbed_official 2:18b05b3173a8 2 * Copyright (c) 2006-2014 ARM Limited
mbed_official 2:18b05b3173a8 3 *
mbed_official 2:18b05b3173a8 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 2:18b05b3173a8 5 * you may not use this file except in compliance with the License.
mbed_official 2:18b05b3173a8 6 * You may obtain a copy of the License at
mbed_official 2:18b05b3173a8 7 *
mbed_official 2:18b05b3173a8 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 2:18b05b3173a8 9 *
mbed_official 2:18b05b3173a8 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 2:18b05b3173a8 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 2:18b05b3173a8 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 2:18b05b3173a8 13 * See the License for the specific language governing permissions and
mbed_official 2:18b05b3173a8 14 * limitations under the License.
mbed_official 2:18b05b3173a8 15 */
mbed_official 2:18b05b3173a8 16
mbed_official 2:18b05b3173a8 17 #include <mbed-events/events.h>
mbed_official 2:18b05b3173a8 18 #include <mbed.h>
mbed_official 2:18b05b3173a8 19 #include "ble/BLE.h"
mbed_official 2:18b05b3173a8 20 #include "ble/Gap.h"
mbed_official 2:18b05b3173a8 21 #include "ble/services/BatteryService.h"
mbed_official 2:18b05b3173a8 22
mbed_official 2:18b05b3173a8 23 DigitalOut led1(LED1, 1);
mbed_official 2:18b05b3173a8 24
mbed_official 2:18b05b3173a8 25 const static char DEVICE_NAME[] = "BATTERY";
mbed_official 2:18b05b3173a8 26 static const uint16_t uuid16_list[] = {GattService::UUID_BATTERY_SERVICE};
mbed_official 2:18b05b3173a8 27
mbed_official 2:18b05b3173a8 28 static uint8_t batteryLevel = 50;
mbed_official 2:18b05b3173a8 29 static BatteryService* batteryServicePtr;
mbed_official 2:18b05b3173a8 30
mbed_official 2:18b05b3173a8 31 static EventQueue eventQueue(
mbed_official 2:18b05b3173a8 32 /* event count */ 16 * /* event size */ 32
mbed_official 2:18b05b3173a8 33 );
mbed_official 2:18b05b3173a8 34
mbed_official 2:18b05b3173a8 35 void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *params)
mbed_official 2:18b05b3173a8 36 {
mbed_official 2:18b05b3173a8 37 BLE::Instance().gap().startAdvertising();
mbed_official 2:18b05b3173a8 38 }
mbed_official 2:18b05b3173a8 39
mbed_official 2:18b05b3173a8 40 void updateSensorValue() {
mbed_official 2:18b05b3173a8 41 batteryLevel++;
mbed_official 2:18b05b3173a8 42 if (batteryLevel > 100) {
mbed_official 2:18b05b3173a8 43 batteryLevel = 20;
mbed_official 2:18b05b3173a8 44 }
mbed_official 2:18b05b3173a8 45
mbed_official 2:18b05b3173a8 46 batteryServicePtr->updateBatteryLevel(batteryLevel);
mbed_official 2:18b05b3173a8 47 }
mbed_official 2:18b05b3173a8 48
mbed_official 2:18b05b3173a8 49 void blinkCallback(void)
mbed_official 2:18b05b3173a8 50 {
mbed_official 2:18b05b3173a8 51 led1 = !led1; /* Do blinky on LED1 while we're waiting for BLE events */
mbed_official 2:18b05b3173a8 52
mbed_official 2:18b05b3173a8 53 BLE &ble = BLE::Instance();
mbed_official 2:18b05b3173a8 54 if (ble.gap().getState().connected) {
mbed_official 2:18b05b3173a8 55 eventQueue.post(updateSensorValue);
mbed_official 2:18b05b3173a8 56 }
mbed_official 2:18b05b3173a8 57 }
mbed_official 2:18b05b3173a8 58
mbed_official 2:18b05b3173a8 59 /**
mbed_official 2:18b05b3173a8 60 * This function is called when the ble initialization process has failled
mbed_official 2:18b05b3173a8 61 */
mbed_official 2:18b05b3173a8 62 void onBleInitError(BLE &ble, ble_error_t error)
mbed_official 2:18b05b3173a8 63 {
mbed_official 2:18b05b3173a8 64 /* Initialization error handling should go here */
mbed_official 2:18b05b3173a8 65 }
mbed_official 2:18b05b3173a8 66
mbed_official 2:18b05b3173a8 67 /**
mbed_official 2:18b05b3173a8 68 * Callback triggered when the ble initialization process has finished
mbed_official 2:18b05b3173a8 69 */
mbed_official 2:18b05b3173a8 70 void bleInitComplete(BLE::InitializationCompleteCallbackContext *params)
mbed_official 2:18b05b3173a8 71 {
mbed_official 2:18b05b3173a8 72 BLE& ble = params->ble;
mbed_official 2:18b05b3173a8 73 ble_error_t error = params->error;
mbed_official 2:18b05b3173a8 74
mbed_official 2:18b05b3173a8 75 if (error != BLE_ERROR_NONE) {
mbed_official 2:18b05b3173a8 76 /* In case of error, forward the error handling to onBleInitError */
mbed_official 2:18b05b3173a8 77 onBleInitError(ble, error);
mbed_official 2:18b05b3173a8 78 return;
mbed_official 2:18b05b3173a8 79 }
mbed_official 2:18b05b3173a8 80
mbed_official 2:18b05b3173a8 81 /* Ensure that it is the default instance of BLE */
mbed_official 2:18b05b3173a8 82 if(ble.getInstanceID() != BLE::DEFAULT_INSTANCE) {
mbed_official 2:18b05b3173a8 83 return;
mbed_official 2:18b05b3173a8 84 }
mbed_official 2:18b05b3173a8 85
mbed_official 2:18b05b3173a8 86 ble.gap().onDisconnection(disconnectionCallback);
mbed_official 2:18b05b3173a8 87
mbed_official 2:18b05b3173a8 88 /* Setup primary service */
mbed_official 2:18b05b3173a8 89 batteryServicePtr = new BatteryService(ble, batteryLevel);
mbed_official 2:18b05b3173a8 90
mbed_official 2:18b05b3173a8 91 /* Setup advertising */
mbed_official 2:18b05b3173a8 92 ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED | GapAdvertisingData::LE_GENERAL_DISCOVERABLE);
mbed_official 2:18b05b3173a8 93 ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LIST_16BIT_SERVICE_IDS, (uint8_t *) uuid16_list, sizeof(uuid16_list));
mbed_official 2:18b05b3173a8 94 ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *) DEVICE_NAME, sizeof(DEVICE_NAME));
mbed_official 2:18b05b3173a8 95 ble.gap().setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);
mbed_official 2:18b05b3173a8 96 ble.gap().setAdvertisingInterval(1000); /* 1000ms */
mbed_official 2:18b05b3173a8 97 ble.gap().startAdvertising();
mbed_official 2:18b05b3173a8 98 }
mbed_official 2:18b05b3173a8 99
mbed_official 2:18b05b3173a8 100 void scheduleBleEventsProcessing(BLE::OnEventsToProcessCallbackContext* context) {
mbed_official 2:18b05b3173a8 101 BLE &ble = BLE::Instance();
mbed_official 2:18b05b3173a8 102 eventQueue.post(Callback<void()>(&ble, &BLE::processEvents));
mbed_official 2:18b05b3173a8 103 }
mbed_official 2:18b05b3173a8 104
mbed_official 2:18b05b3173a8 105 int main()
mbed_official 2:18b05b3173a8 106 {
mbed_official 2:18b05b3173a8 107 eventQueue.post_every(500, blinkCallback);
mbed_official 2:18b05b3173a8 108
mbed_official 2:18b05b3173a8 109 BLE &ble = BLE::Instance();
mbed_official 2:18b05b3173a8 110 ble.onEventsToProcess(scheduleBleEventsProcessing);
mbed_official 2:18b05b3173a8 111 ble.init(bleInitComplete);
mbed_official 2:18b05b3173a8 112
mbed_official 2:18b05b3173a8 113 while (true) {
mbed_official 2:18b05b3173a8 114 eventQueue.dispatch();
mbed_official 2:18b05b3173a8 115 }
mbed_official 2:18b05b3173a8 116
mbed_official 2:18b05b3173a8 117 return 0;
mbed_official 2:18b05b3173a8 118 }