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

[Sensors]

The service would be the standard HRM service. All the central would have to do is receive that data and pass it on.

Potentially I could get the data by other means, but it needs to be relatively user friendly without being too compliated :/

I'll have a look at the other standalone BLE chips vs the nRF52. BOM cost is obviously a significant factor so I need to weight that up against assembly/programming complexity.

No way in hell am I gonna be bit-banging USB though!