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.

Committer:
mbed_official
Date:
Thu Aug 15 17:01:56 2019 +0100
Revision:
79:4c62b7c6081a
Parent:
74:51fde11a771f
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 74:51fde11a771f 1 /* mbed Microcontroller Library
mbed_official 74:51fde11a771f 2 * Copyright (c) 2018 ARM Limited
mbed_official 74:51fde11a771f 3 *
mbed_official 74:51fde11a771f 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 74:51fde11a771f 5 * you may not use this file except in compliance with the License.
mbed_official 74:51fde11a771f 6 * You may obtain a copy of the License at
mbed_official 74:51fde11a771f 7 *
mbed_official 74:51fde11a771f 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 74:51fde11a771f 9 *
mbed_official 74:51fde11a771f 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 74:51fde11a771f 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 74:51fde11a771f 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 74:51fde11a771f 13 * See the License for the specific language governing permissions and
mbed_official 74:51fde11a771f 14 * limitations under the License.
mbed_official 74:51fde11a771f 15 */
mbed_official 74:51fde11a771f 16
mbed_official 74:51fde11a771f 17 #include <mbed.h>
mbed_official 74:51fde11a771f 18 #include "ble/BLE.h"
mbed_official 74:51fde11a771f 19
mbed_official 74:51fde11a771f 20 inline void print_error(ble_error_t error, const char* msg)
mbed_official 74:51fde11a771f 21 {
mbed_official 74:51fde11a771f 22 printf("%s: ", msg);
mbed_official 74:51fde11a771f 23 switch(error) {
mbed_official 74:51fde11a771f 24 case BLE_ERROR_NONE:
mbed_official 74:51fde11a771f 25 printf("BLE_ERROR_NONE: No error");
mbed_official 74:51fde11a771f 26 break;
mbed_official 74:51fde11a771f 27 case BLE_ERROR_BUFFER_OVERFLOW:
mbed_official 74:51fde11a771f 28 printf("BLE_ERROR_BUFFER_OVERFLOW: The requested action would cause a buffer overflow and has been aborted");
mbed_official 74:51fde11a771f 29 break;
mbed_official 74:51fde11a771f 30 case BLE_ERROR_NOT_IMPLEMENTED:
mbed_official 74:51fde11a771f 31 printf("BLE_ERROR_NOT_IMPLEMENTED: Requested a feature that isn't yet implement or isn't supported by the target HW");
mbed_official 74:51fde11a771f 32 break;
mbed_official 74:51fde11a771f 33 case BLE_ERROR_PARAM_OUT_OF_RANGE:
mbed_official 74:51fde11a771f 34 printf("BLE_ERROR_PARAM_OUT_OF_RANGE: One of the supplied parameters is outside the valid range");
mbed_official 74:51fde11a771f 35 break;
mbed_official 74:51fde11a771f 36 case BLE_ERROR_INVALID_PARAM:
mbed_official 74:51fde11a771f 37 printf("BLE_ERROR_INVALID_PARAM: One of the supplied parameters is invalid");
mbed_official 74:51fde11a771f 38 break;
mbed_official 74:51fde11a771f 39 case BLE_STACK_BUSY:
mbed_official 74:51fde11a771f 40 printf("BLE_STACK_BUSY: The stack is busy");
mbed_official 74:51fde11a771f 41 break;
mbed_official 74:51fde11a771f 42 case BLE_ERROR_INVALID_STATE:
mbed_official 74:51fde11a771f 43 printf("BLE_ERROR_INVALID_STATE: Invalid state");
mbed_official 74:51fde11a771f 44 break;
mbed_official 74:51fde11a771f 45 case BLE_ERROR_NO_MEM:
mbed_official 74:51fde11a771f 46 printf("BLE_ERROR_NO_MEM: Out of Memory");
mbed_official 74:51fde11a771f 47 break;
mbed_official 74:51fde11a771f 48 case BLE_ERROR_OPERATION_NOT_PERMITTED:
mbed_official 74:51fde11a771f 49 printf("BLE_ERROR_OPERATION_NOT_PERMITTED");
mbed_official 74:51fde11a771f 50 break;
mbed_official 74:51fde11a771f 51 case BLE_ERROR_INITIALIZATION_INCOMPLETE:
mbed_official 74:51fde11a771f 52 printf("BLE_ERROR_INITIALIZATION_INCOMPLETE");
mbed_official 74:51fde11a771f 53 break;
mbed_official 74:51fde11a771f 54 case BLE_ERROR_ALREADY_INITIALIZED:
mbed_official 74:51fde11a771f 55 printf("BLE_ERROR_ALREADY_INITIALIZED");
mbed_official 74:51fde11a771f 56 break;
mbed_official 74:51fde11a771f 57 case BLE_ERROR_UNSPECIFIED:
mbed_official 74:51fde11a771f 58 printf("BLE_ERROR_UNSPECIFIED: Unknown error");
mbed_official 74:51fde11a771f 59 break;
mbed_official 74:51fde11a771f 60 case BLE_ERROR_INTERNAL_STACK_FAILURE:
mbed_official 74:51fde11a771f 61 printf("BLE_ERROR_INTERNAL_STACK_FAILURE: internal stack faillure");
mbed_official 74:51fde11a771f 62 break;
mbed_official 74:51fde11a771f 63 }
mbed_official 74:51fde11a771f 64 printf("\r\n");
mbed_official 74:51fde11a771f 65 }
mbed_official 74:51fde11a771f 66
mbed_official 74:51fde11a771f 67 /** print device address to the terminal */
mbed_official 74:51fde11a771f 68 inline void print_address(const Gap::Address_t &addr)
mbed_official 74:51fde11a771f 69 {
mbed_official 74:51fde11a771f 70 printf("%02x:%02x:%02x:%02x:%02x:%02x\r\n",
mbed_official 74:51fde11a771f 71 addr[5], addr[4], addr[3], addr[2], addr[1], addr[0]);
mbed_official 74:51fde11a771f 72 }
mbed_official 74:51fde11a771f 73
mbed_official 74:51fde11a771f 74 inline void print_mac_address()
mbed_official 74:51fde11a771f 75 {
mbed_official 74:51fde11a771f 76 /* Print out device MAC address to the console*/
mbed_official 74:51fde11a771f 77 Gap::AddressType_t addr_type;
mbed_official 74:51fde11a771f 78 Gap::Address_t address;
mbed_official 74:51fde11a771f 79 BLE::Instance().gap().getAddress(&addr_type, address);
mbed_official 74:51fde11a771f 80 printf("DEVICE MAC ADDRESS: ");
mbed_official 74:51fde11a771f 81 print_address(address);
mbed_official 74:51fde11a771f 82 }
mbed_official 74:51fde11a771f 83
mbed_official 74:51fde11a771f 84 inline const char* phy_to_string(Gap::Phy_t phy) {
mbed_official 74:51fde11a771f 85 switch(phy.value()) {
mbed_official 74:51fde11a771f 86 case Gap::Phy_t::LE_1M:
mbed_official 74:51fde11a771f 87 return "LE 1M";
mbed_official 74:51fde11a771f 88 case Gap::Phy_t::LE_2M:
mbed_official 74:51fde11a771f 89 return "LE 2M";
mbed_official 74:51fde11a771f 90 case Gap::Phy_t::LE_CODED:
mbed_official 74:51fde11a771f 91 return "LE coded";
mbed_official 74:51fde11a771f 92 default:
mbed_official 74:51fde11a771f 93 return "invalid PHY";
mbed_official 74:51fde11a771f 94 }
mbed_official 74:51fde11a771f 95 }