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/pretty_printer.h@81:99e70947653f, 2019-08-15 (annotated)

Committer:
mbed_official
Date:
Thu Aug 15 17:00:38 2019 +0100
Revision:
81:99e70947653f
Parent:
76:e489712bcbcf 
Merge pull request #252 from donatieng/mbed_os_update



Update Master branch to use Mbed OS 5.13.1

.

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

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 76:e489712bcbcf 1 /* mbed Microcontroller Library
mbed_official 76:e489712bcbcf 2 * Copyright (c) 2018 ARM Limited
mbed_official 76:e489712bcbcf 3 *
mbed_official 76:e489712bcbcf 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 76:e489712bcbcf 5 * you may not use this file except in compliance with the License.
mbed_official 76:e489712bcbcf 6 * You may obtain a copy of the License at
mbed_official 76:e489712bcbcf 7 *
mbed_official 76:e489712bcbcf 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 76:e489712bcbcf 9 *
mbed_official 76:e489712bcbcf 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 76:e489712bcbcf 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 76:e489712bcbcf 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 76:e489712bcbcf 13 * See the License for the specific language governing permissions and
mbed_official 76:e489712bcbcf 14 * limitations under the License.
mbed_official 76:e489712bcbcf 15 */
mbed_official 76:e489712bcbcf 16
mbed_official 76:e489712bcbcf 17 #include <mbed.h>
mbed_official 76:e489712bcbcf 18 #include "ble/BLE.h"
mbed_official 76:e489712bcbcf 19
mbed_official 76:e489712bcbcf 20 inline void print_error(ble_error_t error, const char* msg)
mbed_official 76:e489712bcbcf 21 {
mbed_official 76:e489712bcbcf 22 printf("%s: ", msg);
mbed_official 76:e489712bcbcf 23 switch(error) {
mbed_official 76:e489712bcbcf 24 case BLE_ERROR_NONE:
mbed_official 76:e489712bcbcf 25 printf("BLE_ERROR_NONE: No error");
mbed_official 76:e489712bcbcf 26 break;
mbed_official 76:e489712bcbcf 27 case BLE_ERROR_BUFFER_OVERFLOW:
mbed_official 76:e489712bcbcf 28 printf("BLE_ERROR_BUFFER_OVERFLOW: The requested action would cause a buffer overflow and has been aborted");
mbed_official 76:e489712bcbcf 29 break;
mbed_official 76:e489712bcbcf 30 case BLE_ERROR_NOT_IMPLEMENTED:
mbed_official 76:e489712bcbcf 31 printf("BLE_ERROR_NOT_IMPLEMENTED: Requested a feature that isn't yet implement or isn't supported by the target HW");
mbed_official 76:e489712bcbcf 32 break;
mbed_official 76:e489712bcbcf 33 case BLE_ERROR_PARAM_OUT_OF_RANGE:
mbed_official 76:e489712bcbcf 34 printf("BLE_ERROR_PARAM_OUT_OF_RANGE: One of the supplied parameters is outside the valid range");
mbed_official 76:e489712bcbcf 35 break;
mbed_official 76:e489712bcbcf 36 case BLE_ERROR_INVALID_PARAM:
mbed_official 76:e489712bcbcf 37 printf("BLE_ERROR_INVALID_PARAM: One of the supplied parameters is invalid");
mbed_official 76:e489712bcbcf 38 break;
mbed_official 76:e489712bcbcf 39 case BLE_STACK_BUSY:
mbed_official 76:e489712bcbcf 40 printf("BLE_STACK_BUSY: The stack is busy");
mbed_official 76:e489712bcbcf 41 break;
mbed_official 76:e489712bcbcf 42 case BLE_ERROR_INVALID_STATE:
mbed_official 76:e489712bcbcf 43 printf("BLE_ERROR_INVALID_STATE: Invalid state");
mbed_official 76:e489712bcbcf 44 break;
mbed_official 76:e489712bcbcf 45 case BLE_ERROR_NO_MEM:
mbed_official 76:e489712bcbcf 46 printf("BLE_ERROR_NO_MEM: Out of Memory");
mbed_official 76:e489712bcbcf 47 break;
mbed_official 76:e489712bcbcf 48 case BLE_ERROR_OPERATION_NOT_PERMITTED:
mbed_official 76:e489712bcbcf 49 printf("BLE_ERROR_OPERATION_NOT_PERMITTED");
mbed_official 76:e489712bcbcf 50 break;
mbed_official 76:e489712bcbcf 51 case BLE_ERROR_INITIALIZATION_INCOMPLETE:
mbed_official 76:e489712bcbcf 52 printf("BLE_ERROR_INITIALIZATION_INCOMPLETE");
mbed_official 76:e489712bcbcf 53 break;
mbed_official 76:e489712bcbcf 54 case BLE_ERROR_ALREADY_INITIALIZED:
mbed_official 76:e489712bcbcf 55 printf("BLE_ERROR_ALREADY_INITIALIZED");
mbed_official 76:e489712bcbcf 56 break;
mbed_official 76:e489712bcbcf 57 case BLE_ERROR_UNSPECIFIED:
mbed_official 76:e489712bcbcf 58 printf("BLE_ERROR_UNSPECIFIED: Unknown error");
mbed_official 76:e489712bcbcf 59 break;
mbed_official 76:e489712bcbcf 60 case BLE_ERROR_INTERNAL_STACK_FAILURE:
mbed_official 76:e489712bcbcf 61 printf("BLE_ERROR_INTERNAL_STACK_FAILURE: internal stack faillure");
mbed_official 76:e489712bcbcf 62 break;
mbed_official 76:e489712bcbcf 63 }
mbed_official 76:e489712bcbcf 64 printf("\r\n");
mbed_official 76:e489712bcbcf 65 }
mbed_official 76:e489712bcbcf 66
mbed_official 76:e489712bcbcf 67 /** print device address to the terminal */
mbed_official 76:e489712bcbcf 68 inline void print_address(const Gap::Address_t &addr)
mbed_official 76:e489712bcbcf 69 {
mbed_official 76:e489712bcbcf 70 printf("%02x:%02x:%02x:%02x:%02x:%02x\r\n",
mbed_official 76:e489712bcbcf 71 addr[5], addr[4], addr[3], addr[2], addr[1], addr[0]);
mbed_official 76:e489712bcbcf 72 }
mbed_official 76:e489712bcbcf 73
mbed_official 76:e489712bcbcf 74 inline void print_mac_address()
mbed_official 76:e489712bcbcf 75 {
mbed_official 76:e489712bcbcf 76 /* Print out device MAC address to the console*/
mbed_official 76:e489712bcbcf 77 Gap::AddressType_t addr_type;
mbed_official 76:e489712bcbcf 78 Gap::Address_t address;
mbed_official 76:e489712bcbcf 79 BLE::Instance().gap().getAddress(&addr_type, address);
mbed_official 76:e489712bcbcf 80 printf("DEVICE MAC ADDRESS: ");
mbed_official 76:e489712bcbcf 81 print_address(address);
mbed_official 76:e489712bcbcf 82 }
mbed_official 76:e489712bcbcf 83
mbed_official 76:e489712bcbcf 84 inline const char* phy_to_string(Gap::Phy_t phy) {
mbed_official 76:e489712bcbcf 85 switch(phy.value()) {
mbed_official 76:e489712bcbcf 86 case Gap::Phy_t::LE_1M:
mbed_official 76:e489712bcbcf 87 return "LE 1M";
mbed_official 76:e489712bcbcf 88 case Gap::Phy_t::LE_2M:
mbed_official 76:e489712bcbcf 89 return "LE 2M";
mbed_official 76:e489712bcbcf 90 case Gap::Phy_t::LE_CODED:
mbed_official 76:e489712bcbcf 91 return "LE coded";
mbed_official 76:e489712bcbcf 92 default:
mbed_official 76:e489712bcbcf 93 return "invalid PHY";
mbed_official 76:e489712bcbcf 94 }
mbed_official 76:e489712bcbcf 95 }