Hello Dialog team!
We are currently try to get the highest transfer rate with BLE4.2 and BLE5 features.
For this, we use 2 DA14585, one is slave, the other is central.
Once central is connected to the slave, it enables notification on one of the characteristics.
A button press on the slave triggers burst notifications.
To enable BLE4.2 and BLE5 features, we use the following options in code:
- connection interval set to 8 ms
- ce_len_min / ce_len_max set to 0
- MTU at 255 by calling gattc_set_mtu(0, 255); on slave side on connection
- defined AUTO_DATA_LENGTH_NEGOTIATION_UPON_NEW_CONNECTION
- the characteristic to be transmitted is 251 bytes long
With those options, we reach a bandwidth of 260 kbps, which is quite good, but not as much as expected in BLE5.
If we set the connection interval to 100 ms, we can check that 251 values are sent through 1 long packet, every connection interval (see attached picture).
So Data length extension is enabled.
However, we wonder why is this case the DA14585 does not send more than 1 packet by connection interval. Setting ce_len_min / ce_len_max to 0 we thought the central would allow more packets after the first one.
We also try to set ce_len_min / ce_len_max to 100 ms, but same result.
As a second enhancement, we wonder if the PHY LE 2M is this supported by the DA14585 (core v5 §3.2.2) ? How can we enable this?
Thanks for helping.
Hi eolanecaen,
关于PHY LE 2M，没有从585的堆栈中支持该功能。关于DLE的问题以及为什么设备在相同的连接间隔中没有启动新事务，就我可以从电源分析器中告诉外围设备有更多数据来发送。我假设该设备有更多的数据发送，因为我可以看到外围设备的RX打开，以便侦听中心（从未提出过设备以发送其余数据），但我可以“T究竟究竟发生了什么，如果设备确实有更多的数据发送，除非我有嗅探器日志。您能否请尝试将最大值放在CE_LEN_MAX（0xFFFF）中，并检查一下是否可以在一个连接事件中发送更多数据包？此外，如果您有嗅探器捕获，它也会有助于检查这一点，因为我无法从功耗中讲解太多。根据经验，是的，如果设备已经有足够的数据缓冲，它将在一个连接间隔中发送比标准尺寸大的数据包。
Thanks MT_dialog
Hello MT_dialog.
Here attached a sniffer capture of an exchange between our central and slave on DA14585.
在连接交换,数据长度扩展enabled, however our sniffer is not able to understand then, displayed packet length is wrong.
We try to send more 3 notifications in a single connection interval, but only one frame is sent by the slave by connection interval.
Connection interval is 30 ms
CE_min is 30 ms
CE_max is 200 ms.
Any hint appreciated!
Best regards
Hi eolanecaen,
I am not able to tell much from the sniffer log as well, all i can see is that the peripheral never comes up the second time for a transaction while this is not the case that the power consumption from the peripheral indicates, i mean the sniffer log indicates that the peripheral never listens for the second time after sending the packet and the power profiler capture indicates that the central never replies while the peripheral is listening. I suppose that the reason for the faulty sniffer log is because of the fact that it doesn't support DLE. The only way i can replicate the issue with 1 or maximum 2 large packets over a connection interval is by limiting the ce_len_min and ce_len_max under the user_central_conf, if for example i set it to 0 then i can see only 1 packet hardly 2 during the connection interval, so are you certain that you are setting this during the connection is established ? You will be able to check that by using the ble_minevttime_get() function.
Thanks MT_dialog