Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

Dmitry — Fri, 12 Mar 2021 08:53:48 GMT

app_usbd_cdc_acm_write() doesn't use any internal buffers, it passes your data directly to nrfx_usbd_ep_transfer() - each packet contains a short string instead of 64 bytes. Try to pass exactly 64 bytes in each write.

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

prithvi25 — Thu, 11 Mar 2021 10:10:07 GMT

devzone.nordicsemi.com/.../0407.usbd_5F00_cdc_5F00_acm.zip

I have attached my code. Currently, it only has a USB CDC Serial which gives a 98 KB/s data rate. if that can reach 200 KB/s or more then it also works for me.

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

Dmitry — Thu, 11 Mar 2021 09:09:51 GMT

[quote userid="80695" url="~/f/nordic-q-a/72596/transmitting-data-via-bluetooth-serial-as-well-as-usb-cdc-serial-but-not-getting-high-data-rates-on-u/299162#299162"]After doing this I am getting about 98 KB/s from device to PC.[/quote]

As for me, it's too low... could you show your code? Maybe your terminal program is not optimized for high-speed transfers. It's better to write your own simple reader.

[quote userid="80695" url="~/f/nordic-q-a/72596/transmitting-data-via-bluetooth-serial-as-well-as-usb-cdc-serial-but-not-getting-high-data-rates-on-u/299162#299162"] I want to send data from nrf52480 to Windows Laptop via USB CDC Serial at 200 KB/s and also send the same data via BT.[/quote]

I don't think it's possible. Maximum achievable troughput over BLE is ~1.4Mbps (175 KB/s), with simultaneous high load over USB bus there will be even slower results.

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

prithvi25 — Thu, 11 Mar 2021 07:30:54 GMT

After doing this I am getting about 98 KB/s from device to PC.

NOTE: I want to send data from nrf52480 to Windows Laptop via USB CDC Serial at 200 KB/s and also send the same data via BT.

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

prithvi25 — Wed, 10 Mar 2021 13:59:18 GMT

I got 3.2KB/s on the code developed by me where I transmit data via BT Serial as well as via USB CDD Serial. (SDK 15.3)

I got 85 KB/s using the usb_cdc_acm example from SDK 17.

I used Coolterm to check the data rate

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

prithvi25 — Wed, 10 Mar 2021 13:55:25 GMT

I'll check this and update you soon

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

Sigurd — Wed, 10 Mar 2021 13:53:20 GMT

Hi,

[quote user=""]I am getting data rates up to 3.2KB/s [/quote][quote user=""]I tried the example code usb_cdc_acm and in that, I got about 85 KB/s.[/quote]

What example did you get 3.2 kB/s with?

What SDK version are you using?

What terminal software on the PC side did you use?

RE: Transmitting data via Bluetooth Serial as well as USB CDC Serial but not getting High data rates on U

Dmitry — Wed, 10 Mar 2021 13:43:46 GMT

Hi,

On my Windows 10 system, the raw throughput of CDC ACM (without BLE connection), as long as I remember, shows 425 KB/s from PC to device. Certainly it depends on host, but USB CDC shouldn't be a bottleneck here. Are you using the latest SDK? If you're trying an usb_cdc_acm example, set READ_SIZE to at least 64 bytes and comment out NRF_LOG_INFO lines in RX handler.