ble speed

[chenwenbin]

I want to speed up the ble transfer,  use the ble_app_uart example,  but the speed is too low ,  sniffer show that the notify pack moredata  is true , but  the follow pack is not the notify pack. what is the mean L2CAP Fragment pack , why so many packs  time is same

 

[Karl Ylvisaker]

Hello,

I want to speed up the ble transfer,  use the ble_app_uart example,  but the speed is too low ,

Please have a look at the SoftDevice throughput documentation. If you make sure that your devices are using the same configuration as detailed in the throughput table you should see similar throughput. Especially with regards to connection interval, connection event length and MTU size.

why so many packs  time is same

You should not use the Time column, but instead, go into View and select Delta Time. This is the actual time between packets - and not the COM port time as shown by the Time field. Please do this, so you may accurately see how many packets  are sent each connection event.

what is the mean L2CAP Fragment pack

If a packet is bigger than the MTU size, the Link Layer breaks the packet into multiple fragments which it can send in multiple packets.

sniffer show that the notify pack moredata  is true , but  the follow pack is not the notify pack.

The most common reason for the central not prompting another packet when the peripheral has set moredata is that the connection event length does not allow for another transmission. Please increase your connection event length and see if this lets you send more packets per connection event.

Best regards,
Karl

[chenwenbin]

Is nrf 52810 not support data length extent (DLE)? What is the mean of connection event length

[Karl Ylvisaker]

Yes, the nRF52810 does indeed support Data Length Extension (DLE). DLE allows the devices to negotiate a payload larger than the original 27 byte limit of BLE prior to 4.2. So in essence, DLE lets you use PDU's of up to 251 bytes.

Connection Event Length is how long the devices may communicate each event. Say for example that you are using a connection even length of 1 ms with a connection interval of 7.5 ms. In this case, every 7.5 ms there will be a connection event, in which the devices may communicate for a total of 1 ms each time. You can read more about this here, or visualize the impact of your connection parameters using the Online Power Profiler.

Best regards,
Karl

[chenwenbin]

thanks for reply. the nRF52810 does indeed support Data Length Extension (DLE).? please see the following picture . that says S112 does not support DLE.

[Karl Ylvisaker]

chenwenbin said:

thanks for reply.

No problem at all, I am happy to help!

chenwenbin said:

please see the following picture . that says S112 does not support DLE.

You are correct that the SoftDevice S112 does not support DLE, but the nRF52810 is also compatible with SoftDevice S113, which does support DLE.

Best regards,
Karl

[chenwenbin]

hello ,  I use " app_uart_put" to sent data on nrf52810 , when the baudrate is 250000,  will lost data sometime,why?   for example I sent 100 bytes data , sometime output 99 bytes 

[Karl Ylvisaker]

Hello again,

Could you elaborate further on the issue? Have you verified which side of the link that is loosing the byte, i.e if it is being sent but not received, or not sent at all?

To ensure no dataloss over a high baudrate datalink you could use hardware flow control.

How are you reading out the bytes sent by app_uart_put? Could it be that the missing byte is interpreted as a formatting characters by your serial monitor, and thus are not displayed like the others?

Best regards,
Karl