Francisco Pinho

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9 years, 1 month ago.

BLEnano uart data logging

Hello mbed guys,

I am starting to work with BLEnano, and I need some questions asked due to some difficulties that I have already felt.

1º- The application that I am trying to build is around biosignals, and I need to send 24 bytes at every 4ms, is that possible with BLEnano (Bluetooth 4.0)? If so, The uart service is the best one for the job?

2º- Is there any way to establish some connection with BLEnano and a pc with a Bluetooth 4.0 dongle, and see the comunication data in a terminal (just like it could be done with 2.1 bluetooth modules), or see the BLEnano at all?

3º- Is there any way to transmit data from BLEnano (slave) and no need for any kind of answer from the server?

Thanks in advance for the answers.

Question relating to:

Bluetooth Low Energy (a.k.a Bluetooth LE, BTLE, Bluetooth Smart)

1 Answer

Rohit Grover
9 years, 1 month ago.

Please refer to http://ble-intros.readthedocs.org/en/latest/InDepth/ConnectionParameters/

4ms is too short a period to be sending something out from a BLE peripheral. The shortest possible advertising interval is 20ms (if you were to use advertisements). The shortest possible connection interval is 7.5ms; that's if you're connected and sending back updates using notifications. Anything else would take more latency. Even if you were to relax the 4ms period to something more reaonsable, UARTService isn't the best vehicle, but could be used; I'd use notifications instead.

if you're on Linux, there are commands such as gatttool to probe communication and get data in a terminal.

"Is there any way to transmit data from BLEnano (slave) and no need for any kind of answer from the server?" The slave (or GAP peripheral) and the server (GATT server) are typically the same device. If you mean to ask whether there is a method of communication between the GAP peripheral (server) and the GAP central (client) which doesn't require the central to respond, then you should look at Notifications and Indications. For the other way around, it is possible to enable WRITE_WITHOUT_RESPONSE.