How to know the central and peripheral are still connected

[Minh]

Hi everybody!!!

I am making a project which use NUS service and I have confuses in connection mode:

• when the central and peripheral do not have data to transfer in connection mode, the system will go to sleep mode or not?.

• If yes, how to check the connection is still on?.

• If no, how can I put the system to sleep mode if there is no data transfer for long time ? And how to wake up without using any interupts(GPIO, UART, I2C.. ) except WDT?

[Torsten Robitzki]

No, in Bluetooth LE, there are still empty PDUs (protocol data units) exchanged, and this is nessary to synchronize the master and slave (central and peropheral). If you do not want this to happen, you have to disconnect the devices.

[Minh]

If devices still exchange empty PDU, does peripheral device go to sleep mode ?

[Susheel Nuguru]

1. The system will still go to sleep mode if you have called sleep funtion in a loop in your main(). The system will however wakeup every connection interval to send empty PDUs to keep the connection alive and then go to sleep again because you are calling sleep function in a loop.

2. Just make sure that you did not get BLE_GAP_EVT_DISCONNECTED event.

[Torsten Robitzki]

If you designed the software, to do so, I would expect the device to do it.

[Konrad Traczyk]

2. Shouldn't checking the m_conn_handle variable be enough? If it is set to 0 - the device is not connected, if anything else - it is connected.