Mass storage with nRF51?

[Sensors]

I have a project that requires a bluetooth central to be used to gather data from a HRM service, which shouldn't be too much of an issue. However, it also has to store this, and other local sensor data to some sort of storage device (perhaps microSD or Flash memory).

I want to be able to access this data from a PC or other device, but I'm not sure if the nRF51 or nRF52 has the ability to support a file system and act as a USB mass storage device. Would I need to use an additional part to make this possible? If so, what options do I have?

Thanks

[RK]

You take the micro SD card out and plug it into a USB adaptor and put it in the computer you want to download the data onto. That's how you access it over USB.

I believe FreeRTOS also has a free FAT filesystem which you can use without the actual RTOS, so you just need to write the SPI driver for the MicroSD card which is tedious but not very hard.

Alternatively since you have bluetooth how about just retransmitting the data over bluetooth to the host computer.

[Sensors]

It's not a viable option to take the SD card out, it must be a self-contained unit. It's awkward, but necessary in this case.

Re-transmitting the data via BLE is potentially an option, but 1GB of data would take over two hours at BLE's 1Mbps.

[RK]

In that case you don't need an SD card and all the expense of the holder if you're not going to take it out again. Just use some cheap SPI addressed soldered in flash memory, cheaper, easier.

If you must have USB then buy a USB capable interface chip, I'm sure FTDI does them, Atmel does them, there's bound to be lots of others, probably come ready-configured to look like serial ports or MSDs and you just need to feed them, probably via SPI again.

[Wojtek]

Do you have power source there? Maybe you could use some module like ex. new raspberry pi, or intel edison, and their in-built BLE? you could access the data by WiFi or something. But it would be much more expensive in mass production.

[Sensors]

RK, will that not interfere or clash with the SPI coming from the nRF51? I've not had to do anything like this before, so I'm not sure about the best way to go about it. I'm also not sure what to search for in terms of part description/name?

Wojtek, unfortunately it has to be a cost effective, scalable design so unfortunately cramming and Edison or rPi in a box won't work :(