[NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

DINH LAM — Fri, 15 Jun 2018 08:40:44 GMT

Hi Einar Thorsrud,

I see, it's clear description enough now.

Thanks for your kind help.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

DINH LAM — Fri, 15 Jun 2018 08:09:40 GMT

Hi Nguyen Hoan Hoang,

Firstly I want to try with Nordic apps as an initial step. I will take time to follow your suggested URL.

Thanks for your kind response.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

Einar Thorsrud — Fri, 15 Jun 2018 07:47:45 GMT

The SDK has a SD card example which demonstrates how to read and write data to an SD car with FatFs. The flash data storage module on the other hand is only intended for using internal flash. (You should not put much emphasis on it being experimental though, as it is used extensively by other modules, such as the peer manager).

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

Nguyen Hoan Hoang — Thu, 14 Jun 2018 20:49:16 GMT

On the phone end, is it your own App that gets the data ? You can use a custom service to send your data. See this blog post about transfer data from UART to BLE the easy way.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

DINH LAM — Thu, 14 Jun 2018 20:14:34 GMT

I appreciate your kind comments.

In case of I have to use SD card, I can only see some simple examples but without pin connection or how to set up the ports:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v14.0.0%2Findex.html

Also the flash data storage implementation is experimental without pin connection/HW configuration description.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

Einar Thorsrud — Thu, 14 Jun 2018 14:42:26 GMT

I see. I do not have any more specific suggestions about UART duplexing, but I think both alternatives should be fairly simple to implement on both sides. You probably want to avoid the logger module in the SDK though, and handle the UART communication yourself, using only the UART driver.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

DINH LAM — Thu, 14 Jun 2018 08:13:19 GMT

The input requirement for my phone's apps is ADPCM format. Yes you are right, I will make the compress on the PC could do it faster and easier than the nRF.

Now I need some information about duplexing both UART applications as your suggestion. In worst case I would think about putting the file into SD card and read from there.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

Einar Thorsrud — Thu, 14 Jun 2018 08:06:52 GMT

Hi,

You may of course be able to compress it, but that depend on your project. As you have a PC in one end then I assume it is easier to compress on that side, and do the decompression on the phone? You can compress audio on the nRF as well, but it may not be as efficient due to the relatively slow CPU (at least if you want to compress the audio real time). If you want to do audio compression on the nRF side, then you could for example consider the Opus codec.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

DINH LAM — Thu, 14 Jun 2018 07:51:40 GMT

Thanks Einar Thorsrud for commenting.

I want to transfer the audio file at one time, as I think it's not big. May be I will split it up by chunks as you said if there is no way to compress it smaller.

From the SDK 14.1 I can't search out some examples to proceed with tranferring a very small file to test it.

RE: [NRF5][adafruit-nrf52-pro-feather] Transfer audio files from PC to Adafruit board, then sending via BLE

Einar Thorsrud — Thu, 14 Jun 2018 07:45:56 GMT

Hi James,

I do not have any experience with the Adafruit Feather nRF52 Pro, but it seems like it has some form of USB<->UART bridge. The nRF52 only have a single UART peripheral, so if you want to both use logging and transfer audio over UART simultaneously, then you need some application specific "protocol" on top of the UART to separate the two data streams. Perhaps a simple TLV format (with only two types: log or audio). Alternatively, you could simply separate on direction, so that that all data to the nRF52 is audio data and all data from the nRF52 is log.
It is difficult to say how much RAM you need for your application without knowing more about it, but the nRF52832 on the Adafruit Feather nRF52 Pro has a total of 64 kB RAM, so it is clearly not possible to fit a 100k B audio file. Do you need to transfer the file in one go, or can you split it up in chunks?
I guess this is application specific. Please note that audio over BLE is not yet standardized, so you will typically need a custom app on the phone side.