Streaming data over BLE without any ACK

RE: Streaming data over BLE without any ACK

Simonr — Wed, 08 Jan 2020 08:23:23 GMT

Yes, apparently there is some two-way communication between the two devices, can you provide a sniffer trace of the connection so we might see what exactly is happening between the two devices.

Best regards,

Simon

RE: Streaming data over BLE without any ACK

Rytis — Tue, 07 Jan 2020 07:58:58 GMT

Hello,

Thank you for your answer.

I have one more question: So if my nRF52840 development board send data using notifications to mobile phone there is no guarantee that smartphone received every packet?

I've done some test based on UART example and noticed that in longer range between devices transfer speed decreases but zero packets are lost, i used notifications. So in my theory smartphone as data receiver send some ACK in lower BLE layer to my development board which is peripheral.

Best regards,

Rytis

RE: Streaming data over BLE without any ACK

Simonr — Tue, 07 Jan 2020 07:24:19 GMT

Hi Rytis

I think you've misunderstood here. Notifications do not need acknowledgments for each packet sent. A notification allows you to queue a certain number of packets before sending, and once the buffer is full, you get a NO_TX_BUFFERS error back from sd_ble_gatts_hvx(). When a packet has been sent you'll get a BLE_EVT_TX_COMPLETE event and should be able to queue further packets.

Indications, however, must do an application layer ACK when sending data, making it slower than notifications.

You can check out this great guide to see how to maximize throughput in your application.

Best regards,

Simon

RE: Streaming data over BLE without any ACK

Rytis — Mon, 06 Jan 2020 11:08:31 GMT

At ~140m. I'm more interesed about the whole idea to have data stream without any ACK. Maybe this is corner case and not many people use sending data without ACK.

So is there any easy or not necessarily easy way to do that?

Thank you

RE: Streaming data over BLE without any ACK

Simonr — Mon, 06 Jan 2020 10:28:40 GMT

At what range is your connection starting to break up? I suggest you take a look at our BLE throughput demo, which shows how to maximize your throughput based on your range and necessary bit rate.

Best regards,

Simon