Further to my previous question here
Can anyone help me understand how the callback function gets revoked itself? The connect function, disconnect function.
BLE custom UUID code source here
Another example is BLEUART which have callback functions:
/*********************************************************************
This is an example for our nRF52 based Bluefruit LE modules
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Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
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MIT license, check LICENSE for more information
All text above, and the splash screen below must be included in
any redistribution
*********************************************************************/
/*
- This sketch demonstrate the central API(). A additional bluefruit
- that has bleuart as peripheral is required for the demo.
*/
#include <bluefruit.h>
BLEClientBas clientBas; // battery client
BLEClientDis clientDis; // device information client
BLEClientUart clientUart; // bleuart client
void setup()
{
Serial.begin(115200);
// while ( !Serial ) delay(10); // for nrf52840 with native usb
Serial.println("Bluefruit52 Central BLEUART Example");
Serial.println("-----------------------------------\n");
// Initialize Bluefruit with maximum connections as Peripheral = 0, Central = 1
// SRAM usage required by SoftDevice will increase dramatically with number of connections
Bluefruit.begin(0, 1);
Bluefruit.setName("Bluefruit52 Central");
// Configure Battery client
clientBas.begin();
// Configure DIS client
clientDis.begin();
// Init BLE Central Uart Serivce
clientUart.begin();
clientUart.setRxCallback(bleuart_rx_callback);
// Increase Blink rate to different from PrPh advertising mode
Bluefruit.setConnLedInterval(250);
// Callbacks for Central
Bluefruit.Central.setConnectCallback(connect_callback);
Bluefruit.Central.setDisconnectCallback(disconnect_callback);
/* Start Central Scanning
- Enable auto scan if disconnected
- Interval = 100 ms, window = 80 ms
- Don't use active scan
- Start(timeout) with timeout = 0 will scan forever (until connected)
*/
Bluefruit.Scanner.setRxCallback(scan_callback);
Bluefruit.Scanner.restartOnDisconnect(true);
Bluefruit.Scanner.setInterval(160, 80); // in unit of 0.625 ms
Bluefruit.Scanner.useActiveScan(false);
Bluefruit.Scanner.start(0); // // 0 = Don't stop scanning after n seconds
}
/**
- Callback invoked when scanner pick up an advertising data
- @param report Structural advertising data
/
void scan_callback(ble_gap_evt_adv_report_t report)
{
// Check if advertising contain BleUart service
if ( Bluefruit.Scanner.checkReportForService(report, clientUart) )
{
Serial.print("BLE UART service detected. Connecting ... ");
// Connect to device with bleuart service in advertising
Bluefruit.Central.connect(report);
}else
{
// For Softdevice v6: after received a report, scanner will be paused
// We need to call Scanner resume() to continue scanning
Bluefruit.Scanner.resume();
}
}
/**
- Callback invoked when an connection is established
- @param conn_handle
*/
void connect_callback(uint16_t conn_handle)
{
Serial.println("Connected");
Serial.print("Dicovering Device Information ... ");
if ( clientDis.discover(conn_handle) )
{
Serial.println("Found it");
char buffer[32+1];
// read and print out Manufacturer
memset(buffer, 0, sizeof(buffer));
if ( clientDis.getManufacturer(buffer, sizeof(buffer)) )
{
Serial.print("Manufacturer: ");
Serial.println(buffer);
}
// read and print out Model Number
memset(buffer, 0, sizeof(buffer));
if ( clientDis.getModel(buffer, sizeof(buffer)) )
{
Serial.print("Model: ");
Serial.println(buffer);
}
Serial.println();
}else
{
Serial.println("Found NONE");
}
Serial.print("Dicovering Battery ... ");
if ( clientBas.discover(conn_handle) )
{
Serial.println("Found it");
Serial.print("Battery level: ");
Serial.print(clientBas.read());
Serial.println("%");
}else
{
Serial.println("Found NONE");
}
Serial.print("Discovering BLE Uart Service ... ");
if ( clientUart.discover(conn_handle) )
{
Serial.println("Found it");
Serial.println("Enable TXD's notify");
clientUart.enableTXD();
Serial.println("Ready to receive from peripheral");
}else
{
Serial.println("Found NONE");
// disconnect since we couldn't find bleuart service
Bluefruit.disconnect(conn_handle);
}
}
/**
- Callback invoked when a connection is dropped
- @param conn_handle
- @param reason is a BLE_HCI_STATUS_CODE which can be found in ble_hci.h
*/
void disconnect_callback(uint16_t conn_handle, uint8_t reason)
{
(void) conn_handle;
(void) reason;
Serial.print("Disconnected, reason = 0x"); Serial.println(reason, HEX);
}
/**
- Callback invoked when uart received data
- @param uart_svc Reference object to the service where the data
- arrived. In this example it is clientUart
*/
void bleuart_rx_callback(BLEClientUart& uart_svc)
{
Serial.print("[RX]: ");
while ( uart_svc.available() )
{
Serial.print( (char) uart_svc.read() );
}
Serial.println();
}
void loop()
{
if ( Bluefruit.Central.connected() )
{
// Not discovered yet
if ( clientUart.discovered() )
{
// Discovered means in working state
// Get Serial input and send to Peripheral
if ( Serial.available() )
{
delay(2); // delay a bit for all characters to arrive
char str[20+1] = { 0 };
Serial.readBytes(str, 20);
clientUart.print( str );
}
}
}
}
The following helps set the callback functions:
clientUart.setRxCallback(bleuart_rx_callback);
...
Bluefruit.Central.setConnectCallback(connect_callback);
...
Bluefruit.Central.setDisconnectCallback(disconnect_callback);
Tracing back the libraries I found :
void BLEPeriph::setConnectCallback( ble_connect_callback_t fp )
{
_connect_cb = fp;
}
void BLEPeriph::setDisconnectCallback( ble_disconnect_callback_t fp )
{
_disconnect_cb = fp;
}
But I can't understand how this initializes the calling of the connect or disconnect function while getting a new connection or break in connection respectively.
