Do you have a requirement from the transfer speed from the phone to the device?
BLE is not really designed for file transfer. The speed is a bit limited, and varies greatly from phone to phone.
The best phones can give you up to ~1.2Mbps, while other phones might only give you 300kbps or less, so this is something you have to take into account.
Also if you want to decode MP3 on the fly, this is not something that we have any examples for. Nor do we have any dedicated hardware in our devices for handling MP3 decompression, so I am not sure how efficiently this can be handled.
I would expect the Nordic device best suited for this is the nRF5340, which has a dual core architecture that provides more than three times the CPU performance of the nRF52 series devices, but this use case is not a common one for Nordic devices.
You might want to consider using a WiFi solution instead, for faster transfer rate, and an MCU that is designed to handle MP3 decoding.
I am looking at once in a month data copy and about 10 songs each of 1min, I understand that the bit rate would define the size of the file,but BLE I believe will give me a power advantage. I will look into nRF5340 as you suggested.
I am looking at once in a month data copy and about 10 songs each of 1min, I understand that the bit rate would define the size of the file,but BLE I believe will give me a power advantage. I will look into nRF5340 as you suggested.
If you only need to transfer that rarely I agree that BLE should be a good option.
I did some googling to try to find some MP3 decoding libraries for embedded systems, and found some Adafruit libraries that are designed to run on ARM Cortex-M4 controllers (like the one in the nRF52 or nRF53 series).
This library is designed to run on the Teensy 3.5 board, which includes a 120MHz Cortex-M4 processor.
The nRF5340 contains both a 128MHz Cortex-M33 and a 64MHz Cortex-M33 core for handling the radio, so it should be more than powerful enough to handle a library similar to the one from Adafruit.
By the way please do not take this as an endorsement of the Adafruit library, there might be better libraries out there. Just an indication that the nRF53 (and maybe even the nRF52) should be powerful enough to handle MP3 decoding.
