USB Communications Device Class (CDC) to improve memory transfer made with BLE

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

Håkon Alseth — Thu, 22 Jun 2023 10:12:19 GMT

Yes, close to those numbers. I would strongly recommend that you test this yourself, to see if it is good enough.

Kind regards,

Håkon

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

LoicOlivier — Wed, 21 Jun 2023 13:16:13 GMT

Allright, that is better than nothing!

So I can expect close to 2 Mbit/s with CDC and closer to 3 Mbit/s with MSC.

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

Håkon Alseth — Wed, 21 Jun 2023 07:08:27 GMT

Unfortunately, it will not significantly increase the speed, but it will be increased.

USB will get you upwards of 3 to 3.5 MBit/s (~400 kB/s), but if you are seeing around 0.7 MBit/s now, it will still be an improvement. Note that Windows USB performance will be a bit lower.

Kind regards,

Håkon

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

LoicOlivier — Tue, 20 Jun 2023 17:03:25 GMT

So this means I won't have better speed using USB compared to what I already have with bluetooth ?

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

Håkon Alseth — Tue, 20 Jun 2023 15:36:09 GMT

The USBD is a full speed device, meaning that the PHY is running on 12 Mbit, but the overall throughput will be lower as packets needs to be ACKed on the bus.

You can expect up to 400 kbyte/s with Linux, while we see lower on Windows.

Kind regards,

Håkon

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

LoicOlivier — Tue, 20 Jun 2023 15:21:43 GMT

Not sure to understand, sorry.

How fast can I transfer the data from the nRF to a host (PC), and what should I use (eg. MSC, CDC, ...).

I won't be sending any data from the PC to the nRF, I juste want to get the data from the flash memory on the nRF device and send it as quick as possible to a PC via USB!

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

Håkon Alseth — Tue, 20 Jun 2023 14:55:38 GMT

Hi,

[quote user="LoicOlivier"]I guess MSC is my best option in order to maximise the USB module 12 Mbit/s maximum speed.[/quote]

Sorry, I should have clarified what I meant. By this, I mean storing the data to a medium and reading that directly using a PC or similar.

If you run MSC through the nRF, you will get similar speeds as with CDC.

Kind regards,

Håkon

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

LoicOlivier — Tue, 20 Jun 2023 14:22:31 GMT

Bluetooth is 2 Mbit/s 'on air' which is approx 0.7 Mbit/s effective. It is to close to the CDC 2 Mbit/s achievable speed which you are describing.

I guess MSC is my best option in order to maximise the USB module 12 Mbit/s maximum speed.

RE: USB Communications Device Class (CDC) to improve memory transfer made with BLE

Håkon Alseth — Tue, 20 Jun 2023 11:53:39 GMT

Hi,

CDC will give you just shy of 2MBit/s:

USB CDC ACM max transfer speed

[quote user=""]via BLE which takes a good amount of time (2-3h hrs).[/quote]

What is the transfer rate that you're seeing right now?

[quote user=""]Is it possible to go much faster this way or I have to use something else like a MSC (massive storage class).[/quote]

This is a solid approach if you're storing large amounts of data.

Kind regards,

Håkon