NRF52840 Peripheral NUS with BIS receiver

[nmiric]

Hi Nordic Team,

I am working on implementing synchronized sensor sampling on multiple Bluetooth devices that are externally triggered. To achieve this, I have combined the Peripheral NUS example with the ISO Time Sync example.

Currently, the data throughput with only the NUS enabled is around 900 kbps. However, once I add the ISO Sync (BIS) receiver, the throughput drops to 250 kbps. I’ve noticed that enabling the ISO Sync Receiver in the NUS Peripheral example, with just the configurations CONFIG_BT_OBSERVER=y and CONFIG_BT_ISO_SYNC_RECEIVER=y (without any additional code), also results in a throughput drop to 250 kbps.

Is this expected behaviour? If not, could you please provide guidance on how to proceed?

My primary objective is to asynchronously trigger multiple sensors to sample data simultaneously, as high precision is essential. Furthermore, each sensor should be capable of transmitting data at a rate of 600 kbps.
I have created a BIS transmitter with an SDU interval of 1 second, and I expected not to experience a significant drop in throughput. However, it seems I must be doing something wrong.

My setup consists of two NRF52840DK boards, and I am using NCS 3.0.0.

Thank you for your assistance!

BR,

Nash

[Maria Gilje]

Hello,

The expert who could assist you with this thread isn't available today (long weekend for many in Norway) and is most likely back on Monday.

Currently, the data throughput with only the NUS enabled is around 900 kbps. However, once I add the ISO Sync (BIS) receiver, the throughput drops to 250 kbps. I’ve noticed that enabling the ISO Sync Receiver in the NUS Peripheral example, with just the configurations CONFIG_BT_OBSERVER=y and CONFIG_BT_ISO_SYNC_RECEIVER=y (without any additional code), also results in a throughput drop to 250 kbps.

I took a quick look at this, and my initial hypothesis is that this is related to radio time. The ISO sync BIS receiver needs to scan for the ISO packets, which reduces the time the device can tranceive data with the connected device. I'll ask for a second optinion and test this early next week.

Best regards,

Maria