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

he LED example demonstrates the use of a read-write characteristic to control a LED through a phone app. The canonical source for this example lives at https://github.com/ARMmbed/mbed-os-example-ble/tree/master/BLE_LED

To help you create your own BLE services, we have created this service template. The LED example demonstrates the use of a read-write characteristic to control a LED through a phone app.

The template covers:

  • Setting up advertising and connection states.
  • Assigning UUIDs to the service and its characteristic.
  • Creating an input characteristic: read-write, boolean. This characteristic offers control of the LED.
  • Constructing a service class and adding it to the BLE stack.

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.

  • NOTE:* If you have more than a single mbed board (e.g. nrf51dk or mkit) you can run the BLE_LED and BLE_LEDBlinker at the same time. For more information please refer to the BLE_LEDBlinker demo.

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-LED/raw-file/c6a8f2b3efb6/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 `LED`.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-LED/raw-file/c6a8f2b3efb6/img/scan_results.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-LED/raw-file/c6a8f2b3efb6/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 *LED service* has the UUID `0xA000` and includes the *LED state characteristic* which has the UUID `0xA001`. Depending on your scanner, non standard 16-bit UUID's can be displayed as 128-bit UUID's. If it is the case the following format will be used: `0000XXXX-0000-1000-8000-00805F9B34FB` where `XXXX` is the hexadecimal representation of the 16-bit UUID value.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-LED/raw-file/c6a8f2b3efb6/img/discovery.png

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

  • Open the write pannel of the *LED state* characteristic.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-LED/raw-file/c6a8f2b3efb6/img/write_characteristic.png

figure 5 How to read and write a characteristic value using Master Control Panel 4.0.5

  • The characteristic accept a 1 byte value:

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-LED/raw-file/c6a8f2b3efb6/img/write_pannel.png

figure 6 Write characteristic pannel using Master Control Panel 4.0.5

`0x00`: LED ON

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-LED/raw-file/c6a8f2b3efb6/img/LED_ON.png

figure 6 Write characteristic pannel to set the LED on using Master Control Panel 4.0.5

`0x01`: LED OFF

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-LED/raw-file/c6a8f2b3efb6/img/LED_OFF.png

figure 6 Write characteristic pannel to set the LED off using Master Control Panel 4.0.5

  • Toggle the LED characteristic value and see the LED turn ON or turn OFF according to the value you set.

If you can see the characteristic, and the LED is turned on/off as you toggle its value, the application is working properly.

source/main.cpp@11:7404978b24e7, 2016-10-24 (annotated)

Committer:
mbed_official
Date:
Mon Oct 24 11:15:38 2016 +0100
Revision:
11:7404978b24e7
Parent:
2:864ddfb70a9c
Child:
27:ff1fb7b5f9ee
Merge pull request #32 from ARMmbed/oob



Sync with mbed OS 5.2  OOB repo



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

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 2:864ddfb70a9c 1 /* mbed Microcontroller Library
mbed_official 2:864ddfb70a9c 2 * Copyright (c) 2006-2013 ARM Limited
mbed_official 2:864ddfb70a9c 3 *
mbed_official 2:864ddfb70a9c 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 2:864ddfb70a9c 5 * you may not use this file except in compliance with the License.
mbed_official 2:864ddfb70a9c 6 * You may obtain a copy of the License at
mbed_official 2:864ddfb70a9c 7 *
mbed_official 2:864ddfb70a9c 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 2:864ddfb70a9c 9 *
mbed_official 2:864ddfb70a9c 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 2:864ddfb70a9c 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 2:864ddfb70a9c 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 2:864ddfb70a9c 13 * See the License for the specific language governing permissions and
mbed_official 2:864ddfb70a9c 14 * limitations under the License.
mbed_official 2:864ddfb70a9c 15 */
mbed_official 2:864ddfb70a9c 16
mbed_official 11:7404978b24e7 17 #include <events/mbed_events.h>
mbed_official 2:864ddfb70a9c 18 #include <mbed.h>
mbed_official 2:864ddfb70a9c 19 #include "ble/BLE.h"
mbed_official 2:864ddfb70a9c 20 #include "LEDService.h"
mbed_official 2:864ddfb70a9c 21
mbed_official 2:864ddfb70a9c 22 DigitalOut alivenessLED(LED1, 0);
mbed_official 2:864ddfb70a9c 23 DigitalOut actuatedLED(LED2, 0);
mbed_official 2:864ddfb70a9c 24
mbed_official 2:864ddfb70a9c 25 const static char DEVICE_NAME[] = "LED";
mbed_official 2:864ddfb70a9c 26 static const uint16_t uuid16_list[] = {LEDService::LED_SERVICE_UUID};
mbed_official 2:864ddfb70a9c 27
mbed_official 2:864ddfb70a9c 28 static EventQueue eventQueue(
mbed_official 2:864ddfb70a9c 29 /* event count */ 10 * /* event size */ 32
mbed_official 2:864ddfb70a9c 30 );
mbed_official 2:864ddfb70a9c 31
mbed_official 2:864ddfb70a9c 32 LEDService *ledServicePtr;
mbed_official 2:864ddfb70a9c 33
mbed_official 2:864ddfb70a9c 34 void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *params)
mbed_official 2:864ddfb70a9c 35 {
mbed_official 2:864ddfb70a9c 36 (void) params;
mbed_official 2:864ddfb70a9c 37 BLE::Instance().gap().startAdvertising();
mbed_official 2:864ddfb70a9c 38 }
mbed_official 2:864ddfb70a9c 39
mbed_official 2:864ddfb70a9c 40 void blinkCallback(void)
mbed_official 2:864ddfb70a9c 41 {
mbed_official 2:864ddfb70a9c 42 alivenessLED = !alivenessLED; /* Do blinky on LED1 to indicate system aliveness. */
mbed_official 2:864ddfb70a9c 43 }
mbed_official 2:864ddfb70a9c 44
mbed_official 2:864ddfb70a9c 45 /**
mbed_official 2:864ddfb70a9c 46 * This callback allows the LEDService to receive updates to the ledState Characteristic.
mbed_official 2:864ddfb70a9c 47 *
mbed_official 2:864ddfb70a9c 48 * @param[in] params
mbed_official 2:864ddfb70a9c 49 * Information about the characterisitc being updated.
mbed_official 2:864ddfb70a9c 50 */
mbed_official 2:864ddfb70a9c 51 void onDataWrittenCallback(const GattWriteCallbackParams *params) {
mbed_official 2:864ddfb70a9c 52 if ((params->handle == ledServicePtr->getValueHandle()) && (params->len == 1)) {
mbed_official 2:864ddfb70a9c 53 actuatedLED = *(params->data);
mbed_official 2:864ddfb70a9c 54 }
mbed_official 2:864ddfb70a9c 55 }
mbed_official 2:864ddfb70a9c 56
mbed_official 2:864ddfb70a9c 57 /**
mbed_official 2:864ddfb70a9c 58 * This function is called when the ble initialization process has failled
mbed_official 2:864ddfb70a9c 59 */
mbed_official 2:864ddfb70a9c 60 void onBleInitError(BLE &ble, ble_error_t error)
mbed_official 2:864ddfb70a9c 61 {
mbed_official 2:864ddfb70a9c 62 /* Initialization error handling should go here */
mbed_official 2:864ddfb70a9c 63 }
mbed_official 2:864ddfb70a9c 64
mbed_official 2:864ddfb70a9c 65 /**
mbed_official 2:864ddfb70a9c 66 * Callback triggered when the ble initialization process has finished
mbed_official 2:864ddfb70a9c 67 */
mbed_official 2:864ddfb70a9c 68 void bleInitComplete(BLE::InitializationCompleteCallbackContext *params)
mbed_official 2:864ddfb70a9c 69 {
mbed_official 2:864ddfb70a9c 70 BLE& ble = params->ble;
mbed_official 2:864ddfb70a9c 71 ble_error_t error = params->error;
mbed_official 2:864ddfb70a9c 72
mbed_official 2:864ddfb70a9c 73 if (error != BLE_ERROR_NONE) {
mbed_official 2:864ddfb70a9c 74 /* In case of error, forward the error handling to onBleInitError */
mbed_official 2:864ddfb70a9c 75 onBleInitError(ble, error);
mbed_official 2:864ddfb70a9c 76 return;
mbed_official 2:864ddfb70a9c 77 }
mbed_official 2:864ddfb70a9c 78
mbed_official 2:864ddfb70a9c 79 /* Ensure that it is the default instance of BLE */
mbed_official 2:864ddfb70a9c 80 if(ble.getInstanceID() != BLE::DEFAULT_INSTANCE) {
mbed_official 2:864ddfb70a9c 81 return;
mbed_official 2:864ddfb70a9c 82 }
mbed_official 2:864ddfb70a9c 83
mbed_official 2:864ddfb70a9c 84 ble.gap().onDisconnection(disconnectionCallback);
mbed_official 2:864ddfb70a9c 85 ble.gattServer().onDataWritten(onDataWrittenCallback);
mbed_official 2:864ddfb70a9c 86
mbed_official 2:864ddfb70a9c 87 bool initialValueForLEDCharacteristic = false;
mbed_official 2:864ddfb70a9c 88 ledServicePtr = new LEDService(ble, initialValueForLEDCharacteristic);
mbed_official 2:864ddfb70a9c 89
mbed_official 2:864ddfb70a9c 90 /* setup advertising */
mbed_official 2:864ddfb70a9c 91 ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED | GapAdvertisingData::LE_GENERAL_DISCOVERABLE);
mbed_official 2:864ddfb70a9c 92 ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LIST_16BIT_SERVICE_IDS, (uint8_t *)uuid16_list, sizeof(uuid16_list));
mbed_official 2:864ddfb70a9c 93 ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME));
mbed_official 2:864ddfb70a9c 94 ble.gap().setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);
mbed_official 2:864ddfb70a9c 95 ble.gap().setAdvertisingInterval(1000); /* 1000ms. */
mbed_official 2:864ddfb70a9c 96 ble.gap().startAdvertising();
mbed_official 2:864ddfb70a9c 97 }
mbed_official 2:864ddfb70a9c 98
mbed_official 2:864ddfb70a9c 99 void scheduleBleEventsProcessing(BLE::OnEventsToProcessCallbackContext* context) {
mbed_official 2:864ddfb70a9c 100 BLE &ble = BLE::Instance();
mbed_official 11:7404978b24e7 101 eventQueue.call(Callback<void()>(&ble, &BLE::processEvents));
mbed_official 2:864ddfb70a9c 102 }
mbed_official 2:864ddfb70a9c 103
mbed_official 2:864ddfb70a9c 104 int main()
mbed_official 2:864ddfb70a9c 105 {
mbed_official 11:7404978b24e7 106 eventQueue.call_every(500, blinkCallback);
mbed_official 2:864ddfb70a9c 107
mbed_official 2:864ddfb70a9c 108 BLE &ble = BLE::Instance();
mbed_official 2:864ddfb70a9c 109 ble.onEventsToProcess(scheduleBleEventsProcessing);
mbed_official 2:864ddfb70a9c 110 ble.init(bleInitComplete);
mbed_official 2:864ddfb70a9c 111
mbed_official 11:7404978b24e7 112 eventQueue.dispatch_forever();
mbed_official 2:864ddfb70a9c 113
mbed_official 2:864ddfb70a9c 114 return 0;
mbed_official 2:864ddfb70a9c 115 }