Audio transmission from microphone to smartdevice using nRF52840

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Wed, 19 Aug 2020 08:57:02 GMT

Don't think the example supports any other board than the dev kits. But you need to get some dev kits anyways if you intend to develop and actual product.

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Wed, 19 Aug 2020 08:42:58 GMT

I will give that a try, unfortunately i am prototyping on the Arduino Nano BLE 33 Sense at the moment, not sure if i can test the throughput on this board? I assume its running mbed under the hood?

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Wed, 19 Aug 2020 08:41:44 GMT

No, not really. The main variable is your local RF environment, and that is difficult to estimate.

You really need to investigate yourself. The throughput example in the SDK is set up so that you can measure the throughput between two DKs.

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Tue, 18 Aug 2020 13:12:35 GMT

Makes sense, are there any theoretical values for the range vs. thoughput?

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Tue, 18 Aug 2020 12:34:18 GMT

Not possible at 256kbps.

You will need a PA/LNA and the throughput will most likely be a fair bit lower.

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Mon, 17 Aug 2020 14:45:05 GMT

How about the extended range (1400m) at 1mbps PHY?

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Mon, 17 Aug 2020 14:24:07 GMT

That's certainly possible with any smartphone that has support for extended MTU, Data Length Extension, and 2mbps PHY. I think most smartphones can handle that throughput.

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Mon, 17 Aug 2020 08:52:07 GMT

Honestly, i haven't calculated the throughput needed to stream the audio from the microphone. But if we assume 8kHz (this is application specific) samplerate with 16bit resolution on 1-channel, i would say that 256Kbps should be plenty.

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Mon, 17 Aug 2020 08:41:29 GMT

Alright, I don't know that much about smartphone app development so I can't help much there, but both Android and iOS should have comprehensive guides on how to develop BLE apps.

I suggest you use a custom service, but the Nordic UART Service can get you up and running the fastest. There are probably several open-source projects that have built smartphone apps based on the NUS.

See the /examples/ble_peripheral/ble_app_uart.

What kind of throughput do you need?

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Mon, 17 Aug 2020 08:32:31 GMT

Makes good sense. Well, "somewhat real-time", a bit of delay is acceptable (1-3s), but otherwise we are trying to transmit it somewhat fast. The best reference is a a walkie-talkie application, not a music player.

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Mon, 17 Aug 2020 08:29:58 GMT

Aah.

Well, there's no defined protocol or GATT service for LE audio yet. I suggest you create a Service and Characteristic that can send data at high throughput, and on the smartphone an app that can receive the data stream through the custom Service/Characteristics. Do you intend to stream it in real-time or are you gonna just write to a file?

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Mon, 17 Aug 2020 08:25:10 GMT

So a good portion of patience is needed. Is it realistic to expect anything to be ready by Q1 2021?

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Mon, 17 Aug 2020 08:24:05 GMT

Hi haakansh. Thanks for the reply. I already use the SoC with a microphone. That is not really the challenge. What i am seeking is information about transmitting audio signal from the microphone through BLE.

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Mon, 17 Aug 2020 08:23:57 GMT

The finalization of LE Audio specification is scheduled for Q4 2020 I think, we'll have a demo ready.

RE: Audio transmission from microphone to smartdevice using nRF52840

haakonsh — Mon, 17 Aug 2020 08:22:45 GMT

The nRF52840 has both I2S — Inter-IC sound interface and PDM — Pulse density modulation interface peripherals.

RE: Audio transmission from microphone to smartdevice using nRF52840

Bluetoothy — Mon, 17 Aug 2020 08:14:48 GMT

Which also brings the next question up, is Bluetooth LE Audio around the corner?