Bluetooth Low Energy / Mbed 2 deprecated BLE_GAP_Example

This example program shows how to set up a GAP advertising packet to broadcast data from the device out to anyone who may be listening.

Dependencies:   BLE_API mbed nRF51822

Fork of BLE_EvothingsExample_GAP by Austin Blackstone

Intro

This code is meant to demonstrate how to use the GAP advertising layer to transmit data. Keep in mind you only have 26B of data in the Manufacturer data field to use.

Video of use

Details

Fill in the data you want to transmit by changing the following line, try using the string representation by changing hte "CHangeThisData" field or send hex data by altering the hex data field. 

// You have up to 26 bytes of advertising data to use.
const static uint8_t AdvData[] = {"ChangeThisData"};             // example of character data
//const static uint8_t AdvData[] = {0x01,0x02,0x03,0x04,0x05};   // example of hex data

Name Device

Optionally you can give your device a name by uncommenting the following two lines

//const static char     DEVICE_NAME[]        = "ChangeMe!!"; // change this
...
//ble.accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME));

Add Disconnection Callback

This code is bare bones and as such does not restart advertising when disconnected from a device. To add this functionality into your code please add the following callback

// Restart advertising when phone app disconnects
void disconnectionCallback(Gap::Handle_t handle, Gap::DisconnectionReason_t reason)
{
    ble.startAdvertising(); 
}

and the following initialization to your main function

int 
main(void)
{
...
ble.onDisconnection(disconnectionCallback);
...

Viewing Data

You can use either the LightBlue app on iOS or the nRF Master Control Panel application on Android to view the advertising data. Alternatively you can use a custom Evothings App to view the data.

Evothings?

Evothings is a rapid prototyping environment that uses cordova to enable you to rapidly develop smartphone applications in Javascript. Please download the Evothings workbench to your computer and the Evothings client to your smartphone. In the Evothings Workbench you will find an example program called "mbed Evothings GAP", this Evothings Smartphone App is meant to be used with the above embedded mbed code. For instructions on how to use Evothings please see the reference section below.

Reference

main.cpp

Committer:
andresag
Date:
2016-01-12
Revision:
14:1c15d473b42f
Parent:
13:827dd2b32bb8
Child:
15:7e06fce6e4f8

File content as of revision 14:1c15d473b42f:

#include "mbed.h"
#include "ble/BLE.h"

/* Optional: Device Name, add for human read-ability */
const static char     DEVICE_NAME[] = "ChangeMe!!";

/* You have up to 26 bytes of advertising data to use. */
const static uint8_t AdvData[] = {0x01,0x02,0x03,0x04,0x05};   /* Example of hex data */
//const static uint8_t AdvData[] = {"ChangeThisData"};         /* Example of character data */

/* Optional: Restart advertising when peer disconnects */
void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *params)
{
    BLE::Instance().gap().startAdvertising();
}
/**
 * This function is called when the ble initialization process has failed
 */
void onBleInitError(BLE &ble, ble_error_t error)
{
    /* Avoid compiler warnings */
    (void) ble;
    (void) error;
    
    /* Initialization error handling should go here */
}    

/**
 * Callback triggered when the ble initialization process has finished
 */
void bleInitComplete(BLE::InitializationCompleteCallbackContext *params)
{
    BLE&        ble   = params->ble;
    ble_error_t error = params->error;

    if (error != BLE_ERROR_NONE) {
        /* In case of error, forward the error handling to onBleInitError */
        onBleInitError(ble, error);
        return;
    }

    /* Ensure that it is the default instance of BLE */
    if(ble.getInstanceID() != BLE::DEFAULT_INSTANCE) {
        return;
    }
    
    /* Set device name characteristic data */
    ble.gap().setDeviceName((const uint8_t *) DEVICE_NAME);

    /* Optional: add callback for disconnection */
    ble.gap().onDisconnection(disconnectionCallback);

    /* Sacrifice 3B of 31B to Advertising Flags */
    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED | GapAdvertisingData::LE_GENERAL_DISCOVERABLE );
    ble.gap().setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);

    /* Sacrifice 2B of 31B to AdvType overhead, rest goes to AdvData array you define */
    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::MANUFACTURER_SPECIFIC_DATA, AdvData, sizeof(AdvData));

    /* Optional: Add name to device */
    //ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME));

    /* Set advertising interval. Longer interval == longer battery life */
    ble.gap().setAdvertisingInterval(100); /* 100ms */

    /* Start advertising */
    ble.gap().startAdvertising();
}

int main(void)
{
    BLE& ble = BLE::Instance(BLE::DEFAULT_INSTANCE);
 
    /* Initialize BLE baselayer, always do this first! */
    ble.init(bleInitComplete);

    /* Infinite loop waiting for BLE events */
    while (true) {
        /* Save power while waiting for callback events */
        ble.waitForEvent();
    }
}