BLE UART (NUS), altering MTU and faster interval

[TF mulder]

Hi,

On the nRF5340-DK, i'm succesfuly using the example code:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/bluetooth/peripheral_uart/README.html

I would like to speed up the transfer rate of the TX-characteristic.  (im at the moment not using the uart, im just sending with  bt_nus_send() )

I would like to alter the MTU-size (seems to be set to 65 now), i would like to have this set to maximal  247 (i believe.)

And via nRFconnect-app i see:  the Peripheral Prefered Connection Parameter: connection interval 30 .. 50msec,  this i would like to set faster  e.g. 5 or 10msec

Do i need to put some-things in Kconfig ? or in prj.conf  (i tried  CONFIG_BT_L2CAP_TX_MTU=247    in prj,conf).

But my central on PC-Windows (im using bleak for now)  reveals a MTU = 65.

And in the peripheral  main.c i did  set inside      static void connected(struct bt_conn *conn, uint8_t err)    the code    

LOG_INF("MTU= %d", bt_nus_get_mtu( conn ) )    ;      This prints a MTU = 20.

1) What should i do to set MTU = 247 ?

2) What should i do to get a  faster Interval time ?

Kind Regards,

Theo     

[Simon]

This ticket may help: https://devzone.nordicsemi.com/f/nordic-q-a/83562/file-transfer-large-data-transfer-example-nrf-connect-sdk, where I show how to increase the MTU for the peripheral_uart sample

Also, take a look at the Bluetooth Throughput example: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.8.0/nrf/samples/bluetooth/throughput/README.html 

Best regards,

Simon

[TF mulder]

extention to the message below :-)    oeff  there was an extra X   in CONFIG_BT_CTLR_DATXA_LENGTH_MAX

i now used    CONFIG_BT_CTLR_DATA_LENGTH_MAX      now it gives a remark:  this could not be set: missing dependencies ...

[Simon]

Try this sample with NCS v1.8.0:

peripheral_uart_high_mtu.zip

It is the peripheral_uart sample with higher MTU support as described in https://devzone.nordicsemi.com/f/nordic-q-a/83562/file-transfer-large-data-transfer-example-nrf-connect-sdk

[TF mulder]

Ok Simon, thanks, that worked i have an MTU=247 now.

Now the  second question of my post :

2) What should i do to get a  faster Interval time ?

==> so how can i  (request)/change the interval time ??

--------

by the way.., im using an nRF5340 on the peripheral.  Now i would like to use a Dongle on the PC-side, what device can you recommend?    

nRF52840 Dongle ?   Or is there an other dongle that matches with the nRF5340-peripheral ?

And is there a dongle with a housing?

Thanks, 

Best Regards,

Theo

[Simon]

TF mulder said:

==> so how can i  (request)/change the interval time ??

Check out the Bluetooth throughput sample:

https://github.com/nrfconnect/sdk-nrf/tree/v1.9.0-rc1/samples/bluetooth/throughput 

Follow the instructions Throughput-->Building and running (you need two boards) to run the samples and then study the code, then you will understand how to set the connection interval.

Be aware that a faster connection interval doesn't necessarily mean a higher throughput, see https://devzone.nordicsemi.com/f/nordic-q-a/69999/what-is-the-relation-between-connection-interval-and-the-throughput

TF mulder said:

by the way.., im using an nRF5340 on the peripheral.  Now i would like to use a Dongle on the PC-side, what device can you recommend?    

nRF52840 Dongle ?   Or is there an other dongle that matches with the nRF5340-peripheral ?

We don't have any nRF5340 Dongle, so I think the nRF52840 Dongle is the way to go.

If you have more questions regarding the dongle, could you open a new case, since it is not related to the initial questions (MTU and conn. interval)

Best regards,

Simon

[TF mulder]

Ok thanks Simon