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

This application shows how to use GAP to transmit a simple value to disconnected peer listening for advertisement every time that a value is updated. The canonical source for this example lives at: https://github.com/ARMmbed/mbed-os-example-ble/tree/master/BLE_GAPButton

Button count over GAP

This application shows how to use GAP to transmit a simple value to disconnected peer listening for advertisement every time that a value is updated:

  • The value is a count of how many times a button on the device was pressed (the code actually monitors the button's releases, not press downs).
  • We transmit the value in the SERVICE_DATA field of the advertising payload.

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-GAPButton/raw-file/8f898b781de2/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 `GAPButton`; and look at the advertisement broadcasted by your device (there is no need to connect to your device).

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-GAPButton/raw-file/8f898b781de2/img/discovery.png

figure 2 Scan results using nRF Master Control Panel 4.0.5.

  • The Service Data field of the advertisement packet broadcasted by your device reflects the button press count. The starting value is 0.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-GAPButton/raw-file/8f898b781de2/img/initial_state.png

figure 3 Initial state of the button using nRF Master Control Panel 4.0.5.

  • Press the button on the device.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-GAPButton/raw-file/8f898b781de2/img/first_press.png

figure 3 State after 1 button press using nRF Master Control Panel 4.0.5.

  • The Service Data field value of the advertisement packet should change every time you press the button.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-GAPButton/raw-file/8f898b781de2/img/result.png

figure 3 State after 6 button press using nRF Master Control Panel 4.0.5.

Note

Since broadcasting is not reliable and your phone may scan intermittently, it is possible that your phone will miss button updates.

source/main.cpp@83:5f43cd2a93e6, 2019-04-26 (annotated)

Committer:
mbed_official
Date:
Fri Apr 26 18:01:01 2019 +0100
Revision:
83:5f43cd2a93e6
Parent:
78:3f848aa75a8a 
Merge pull request #230 from LMESTM/NUCLEO_WB55RG_readme



Update readme with some NUCLEO_WB55RG basic info

.

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

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 3:f0ed4199b362 1 /* mbed Microcontroller Library
mbed_official 78:3f848aa75a8a 2 * Copyright (c) 2006-2018 ARM Limited
mbed_official 3:f0ed4199b362 3 *
mbed_official 3:f0ed4199b362 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 3:f0ed4199b362 5 * you may not use this file except in compliance with the License.
mbed_official 3:f0ed4199b362 6 * You may obtain a copy of the License at
mbed_official 3:f0ed4199b362 7 *
mbed_official 3:f0ed4199b362 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 3:f0ed4199b362 9 *
mbed_official 3:f0ed4199b362 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 3:f0ed4199b362 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 3:f0ed4199b362 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 3:f0ed4199b362 13 * See the License for the specific language governing permissions and
mbed_official 3:f0ed4199b362 14 * limitations under the License.
mbed_official 3:f0ed4199b362 15 */
mbed_official 3:f0ed4199b362 16
mbed_official 14:332bb3fa072b 17 #include <events/mbed_events.h>
mbed_official 3:f0ed4199b362 18 #include <mbed.h>
mbed_official 3:f0ed4199b362 19 #include "ble/BLE.h"
mbed_official 78:3f848aa75a8a 20 #include "pretty_printer.h"
mbed_official 3:f0ed4199b362 21
mbed_official 78:3f848aa75a8a 22 static const char DEVICE_NAME[] = "GAPButton";
mbed_official 3:f0ed4199b362 23
mbed_official 78:3f848aa75a8a 24 static EventQueue event_queue(/* event count */ 16 * EVENTS_EVENT_SIZE);
mbed_official 3:f0ed4199b362 25
mbed_official 78:3f848aa75a8a 26 /** Demonstrate advertising, scanning and connecting
mbed_official 78:3f848aa75a8a 27 */
mbed_official 78:3f848aa75a8a 28 class GapButtonDemo : private mbed::NonCopyable<GapButtonDemo>, public ble::Gap::EventHandler
mbed_official 3:f0ed4199b362 29 {
mbed_official 78:3f848aa75a8a 30 public:
mbed_official 78:3f848aa75a8a 31 GapButtonDemo(BLE& ble, events::EventQueue& event_queue) :
mbed_official 78:3f848aa75a8a 32 _ble(ble),
mbed_official 78:3f848aa75a8a 33 _event_queue(event_queue),
mbed_official 78:3f848aa75a8a 34 _led1(LED1, 0),
mbed_official 78:3f848aa75a8a 35 /* We can arbiturarily choose the GAPButton service UUID to be 0xAA00
mbed_official 78:3f848aa75a8a 36 * as long as it does not overlap with the UUIDs defined here:
mbed_official 78:3f848aa75a8a 37 * https://developer.bluetooth.org/gatt/services/Pages/ServicesHome.aspx */
mbed_official 78:3f848aa75a8a 38 _button_uuid(0xAA00),
mbed_official 83:5f43cd2a93e6 39 _button(BLE_BUTTON_PIN_NAME, BLE_BUTTON_PIN_PULL),
mbed_official 78:3f848aa75a8a 40 _adv_data_builder(_adv_buffer) { }
mbed_official 78:3f848aa75a8a 41
mbed_official 78:3f848aa75a8a 42 ~GapButtonDemo()
mbed_official 78:3f848aa75a8a 43 {
mbed_official 78:3f848aa75a8a 44 if (_ble.hasInitialized()) {
mbed_official 78:3f848aa75a8a 45 _ble.shutdown();
mbed_official 78:3f848aa75a8a 46 }
mbed_official 3:f0ed4199b362 47 }
mbed_official 78:3f848aa75a8a 48
mbed_official 78:3f848aa75a8a 49 /** Start BLE interface initialisation */
mbed_official 78:3f848aa75a8a 50 void run()
mbed_official 78:3f848aa75a8a 51 {
mbed_official 78:3f848aa75a8a 52 if (_ble.hasInitialized()) {
mbed_official 78:3f848aa75a8a 53 printf("Ble instance already initialised.\r\n");
mbed_official 78:3f848aa75a8a 54 return;
mbed_official 78:3f848aa75a8a 55 }
mbed_official 3:f0ed4199b362 56
mbed_official 78:3f848aa75a8a 57 /* handle gap events */
mbed_official 78:3f848aa75a8a 58 _ble.gap().setEventHandler(this);
mbed_official 78:3f848aa75a8a 59
mbed_official 78:3f848aa75a8a 60 ble_error_t error = _ble.init(this, &GapButtonDemo::on_init_complete);
mbed_official 3:f0ed4199b362 61
mbed_official 78:3f848aa75a8a 62 if (error) {
mbed_official 78:3f848aa75a8a 63 printf("Error returned by BLE::init.\r\n");
mbed_official 78:3f848aa75a8a 64 return;
mbed_official 78:3f848aa75a8a 65 }
mbed_official 3:f0ed4199b362 66
mbed_official 78:3f848aa75a8a 67 /* to show we're running we'll blink every 500ms */
mbed_official 78:3f848aa75a8a 68 _event_queue.call_every(500, this, &GapButtonDemo::blink);
mbed_official 3:f0ed4199b362 69
mbed_official 78:3f848aa75a8a 70 /* this will not return until shutdown */
mbed_official 78:3f848aa75a8a 71 _event_queue.dispatch_forever();
mbed_official 78:3f848aa75a8a 72 }
mbed_official 3:f0ed4199b362 73
mbed_official 78:3f848aa75a8a 74 private:
mbed_official 78:3f848aa75a8a 75 /** This is called when BLE interface is initialised and starts the first mode */
mbed_official 78:3f848aa75a8a 76 void on_init_complete(BLE::InitializationCompleteCallbackContext *event)
mbed_official 78:3f848aa75a8a 77 {
mbed_official 78:3f848aa75a8a 78 if (event->error) {
mbed_official 78:3f848aa75a8a 79 printf("Error during the initialisation\r\n");
mbed_official 78:3f848aa75a8a 80 return;
mbed_official 78:3f848aa75a8a 81 }
mbed_official 47:70f571463f31 82
mbed_official 78:3f848aa75a8a 83 print_mac_address();
mbed_official 3:f0ed4199b362 84
mbed_official 78:3f848aa75a8a 85 _button.rise(Callback<void()>(this, &GapButtonDemo::button_pressed_callback));
mbed_official 78:3f848aa75a8a 86
mbed_official 78:3f848aa75a8a 87 start_advertising();
mbed_official 3:f0ed4199b362 88 }
mbed_official 3:f0ed4199b362 89
mbed_official 78:3f848aa75a8a 90 void start_advertising() {
mbed_official 78:3f848aa75a8a 91 /* Create advertising parameters and payload */
mbed_official 78:3f848aa75a8a 92
mbed_official 78:3f848aa75a8a 93 ble::AdvertisingParameters adv_parameters(
mbed_official 78:3f848aa75a8a 94 ble::advertising_type_t::CONNECTABLE_UNDIRECTED,
mbed_official 78:3f848aa75a8a 95 ble::adv_interval_t(ble::millisecond_t(1000))
mbed_official 78:3f848aa75a8a 96 );
mbed_official 78:3f848aa75a8a 97
mbed_official 78:3f848aa75a8a 98 _adv_data_builder.setFlags();
mbed_official 78:3f848aa75a8a 99 _adv_data_builder.setLocalServiceList(mbed::make_Span(&_button_uuid, 1));
mbed_official 78:3f848aa75a8a 100 _adv_data_builder.setName(DEVICE_NAME);
mbed_official 78:3f848aa75a8a 101
mbed_official 78:3f848aa75a8a 102 update_button_payload();
mbed_official 78:3f848aa75a8a 103
mbed_official 78:3f848aa75a8a 104 /* Setup advertising */
mbed_official 78:3f848aa75a8a 105
mbed_official 78:3f848aa75a8a 106 ble_error_t error = _ble.gap().setAdvertisingParameters(
mbed_official 78:3f848aa75a8a 107 ble::LEGACY_ADVERTISING_HANDLE,
mbed_official 78:3f848aa75a8a 108 adv_parameters
mbed_official 78:3f848aa75a8a 109 );
mbed_official 3:f0ed4199b362 110
mbed_official 78:3f848aa75a8a 111 if (error) {
mbed_official 78:3f848aa75a8a 112 print_error(error, "_ble.gap().setAdvertisingParameters() failed");
mbed_official 78:3f848aa75a8a 113 return;
mbed_official 78:3f848aa75a8a 114 }
mbed_official 78:3f848aa75a8a 115
mbed_official 78:3f848aa75a8a 116 error = _ble.gap().setAdvertisingPayload(
mbed_official 78:3f848aa75a8a 117 ble::LEGACY_ADVERTISING_HANDLE,
mbed_official 78:3f848aa75a8a 118 _adv_data_builder.getAdvertisingData()
mbed_official 78:3f848aa75a8a 119 );
mbed_official 3:f0ed4199b362 120
mbed_official 78:3f848aa75a8a 121 if (error) {
mbed_official 78:3f848aa75a8a 122 print_error(error, "_ble.gap().setAdvertisingPayload() failed");
mbed_official 78:3f848aa75a8a 123 return;
mbed_official 78:3f848aa75a8a 124 }
mbed_official 78:3f848aa75a8a 125
mbed_official 78:3f848aa75a8a 126 /* Start advertising */
mbed_official 78:3f848aa75a8a 127
mbed_official 78:3f848aa75a8a 128 error = _ble.gap().startAdvertising(ble::LEGACY_ADVERTISING_HANDLE);
mbed_official 78:3f848aa75a8a 129
mbed_official 78:3f848aa75a8a 130 if (error) {
mbed_official 78:3f848aa75a8a 131 print_error(error, "_ble.gap().startAdvertising() failed");
mbed_official 78:3f848aa75a8a 132 return;
mbed_official 78:3f848aa75a8a 133 }
mbed_official 3:f0ed4199b362 134 }
mbed_official 3:f0ed4199b362 135
mbed_official 78:3f848aa75a8a 136 void update_button_payload()
mbed_official 78:3f848aa75a8a 137 {
mbed_official 78:3f848aa75a8a 138 /* The Service Data data type consists of a service UUID with the data associated with that service. */
mbed_official 78:3f848aa75a8a 139 ble_error_t error = _adv_data_builder.setServiceData(
mbed_official 78:3f848aa75a8a 140 _button_uuid,
mbed_official 78:3f848aa75a8a 141 mbed::make_Span(&_button_count, 1)
mbed_official 78:3f848aa75a8a 142 );
mbed_official 78:3f848aa75a8a 143
mbed_official 78:3f848aa75a8a 144 if (error != BLE_ERROR_NONE) {
mbed_official 78:3f848aa75a8a 145 print_error(error, "Updating payload failed");
mbed_official 78:3f848aa75a8a 146 }
mbed_official 78:3f848aa75a8a 147 }
mbed_official 78:3f848aa75a8a 148
mbed_official 78:3f848aa75a8a 149 void button_pressed_callback()
mbed_official 78:3f848aa75a8a 150 {
mbed_official 78:3f848aa75a8a 151 ++_button_count;
mbed_official 78:3f848aa75a8a 152
mbed_official 78:3f848aa75a8a 153 /* Calling BLE api in interrupt context may cause race conditions
mbed_official 78:3f848aa75a8a 154 Using mbed-events to schedule calls to BLE api for safety */
mbed_official 78:3f848aa75a8a 155 _event_queue.call(Callback<void()>(this, &GapButtonDemo::update_button_payload));
mbed_official 3:f0ed4199b362 156 }
mbed_official 3:f0ed4199b362 157
mbed_official 78:3f848aa75a8a 158 /** Blink LED to show we're running */
mbed_official 78:3f848aa75a8a 159 void blink(void)
mbed_official 78:3f848aa75a8a 160 {
mbed_official 78:3f848aa75a8a 161 _led1 = !_led1;
mbed_official 78:3f848aa75a8a 162 }
mbed_official 3:f0ed4199b362 163
mbed_official 78:3f848aa75a8a 164 private:
mbed_official 78:3f848aa75a8a 165 /* Event handler */
mbed_official 3:f0ed4199b362 166
mbed_official 78:3f848aa75a8a 167 void onDisconnectionComplete(const ble::DisconnectionCompleteEvent&) {
mbed_official 78:3f848aa75a8a 168 _ble.gap().startAdvertising(ble::LEGACY_ADVERTISING_HANDLE);
mbed_official 3:f0ed4199b362 169 }
mbed_official 47:70f571463f31 170
mbed_official 78:3f848aa75a8a 171 private:
mbed_official 78:3f848aa75a8a 172 BLE &_ble;
mbed_official 78:3f848aa75a8a 173 events::EventQueue &_event_queue;
mbed_official 78:3f848aa75a8a 174
mbed_official 78:3f848aa75a8a 175 DigitalOut _led1;
mbed_official 78:3f848aa75a8a 176 const UUID _button_uuid;
mbed_official 3:f0ed4199b362 177
mbed_official 78:3f848aa75a8a 178 InterruptIn _button;
mbed_official 78:3f848aa75a8a 179 uint8_t _button_count;
mbed_official 78:3f848aa75a8a 180
mbed_official 78:3f848aa75a8a 181 uint8_t _adv_buffer[ble::LEGACY_ADVERTISING_MAX_SIZE];
mbed_official 78:3f848aa75a8a 182 ble::AdvertisingDataBuilder _adv_data_builder;
mbed_official 78:3f848aa75a8a 183 };
mbed_official 78:3f848aa75a8a 184
mbed_official 78:3f848aa75a8a 185 /** Schedule processing of events from the BLE middleware in the event queue. */
mbed_official 78:3f848aa75a8a 186 void schedule_ble_events(BLE::OnEventsToProcessCallbackContext *context) {
mbed_official 78:3f848aa75a8a 187 event_queue.call(Callback<void()>(&context->ble, &BLE::processEvents));
mbed_official 3:f0ed4199b362 188 }
mbed_official 3:f0ed4199b362 189
mbed_official 3:f0ed4199b362 190 int main()
mbed_official 3:f0ed4199b362 191 {
mbed_official 78:3f848aa75a8a 192 BLE &ble = BLE::Instance();
mbed_official 3:f0ed4199b362 193
mbed_official 78:3f848aa75a8a 194 /* this will inform us of all events so we can schedule their handling
mbed_official 78:3f848aa75a8a 195 * using our event queue */
mbed_official 78:3f848aa75a8a 196 ble.onEventsToProcess(schedule_ble_events);
mbed_official 3:f0ed4199b362 197
mbed_official 78:3f848aa75a8a 198 GapButtonDemo demo(ble, event_queue);
mbed_official 3:f0ed4199b362 199
mbed_official 78:3f848aa75a8a 200 demo.run();
mbed_official 3:f0ed4199b362 201
mbed_official 3:f0ed4199b362 202 return 0;
mbed_official 3:f0ed4199b362 203 }