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

Diff: main.cpp

Revision:
8:5442739198ec
Parent:
7:f9a2fa5b1d43
Child:
11:c9c0c4586c5f
--- a/main.cpp	Tue Mar 10 22:42:14 2015 +0000
+++ b/main.cpp	Tue Mar 17 19:45:19 2015 +0000
@@ -6,21 +6,28 @@
 // BLE object
 BLEDevice ble;
 
-//const static char     DEVICE_NAME[]        = "ChangeMe!!"; // change this
+// Optional name, add for human read-ability
+//const static char     DEVICE_NAME[]        = "ChangeMe!!"; // Optional: device name
 
 /**
-  You have up to 26 bytes of advertising data to use.
-  Make up your own encoding for these 26bytes, send it across
-  and decode it using the evothings app.
+  * You have up to 26 bytes of advertising data to use.
+  * Make up your own encoding for these 26bytes, send it across
+  * and decode it using the evothings app.
  */
-//const static uint8_t AdvData[] = {"ChangeThisData"};             // example of character data
+//const static uint8_t AdvData[] = {"ChangeThisData"};         // example of character data
 const static uint8_t AdvData[] = {0x01,0x02,0x03,0x04,0x05};   // example of hex data
 
+// Restart advertising when phone app disconnects 
+void disconnectionCallback(Gap::Handle_t handle, Gap::DisconnectionReason_t reason){
+    ble.startAdvertising(); 
+}
+
 // main program
 int main(void)
 {
     // Initialize BLE baselayer, always do this first!
     ble.init();
+    // ble.onDisconnection(disconnectionCallback); // Optional: add callback for disconnection
 
     // Sacrifice 3B of 31B to Advertising Flags
     ble.accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED | GapAdvertisingData::LE_GENERAL_DISCOVERABLE );
@@ -29,7 +36,7 @@
     // Sacrifice 2B of 31B to AdvType overhead, rest goes to AdvData array you define
     ble.accumulateAdvertisingPayload(GapAdvertisingData::MANUFACTURER_SPECIFIC_DATA, AdvData, sizeof(AdvData));
     
-    // Add name to device 
+    // Optional: Add name to device 
     //ble.accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME));
 
     // Set advertising interval. Longer interval = longer battery life
@@ -38,6 +45,6 @@
 
     // Infinite loop waiting for BLE events
     for (;;) {
-        ble.waitForEvent(); // this saves battery
+        ble.waitForEvent(); // this saves battery while waiting for callback events
     }
 }