Gazell - transmit 10 bytes in under 2ms

[ImQ009]

Is this even possible? I have a BLE connection with an interval of 7.5 ms. I've set up a radio notification with a distance of 2680us in order to be able to transmit 4 BLE packets. When the notification happens I request a timeslot with the length of 2200us. Now, is it possible to receive 10 bytes with Gazell in such a short time? I wasn't really able to go lower than 3.6ms with the following settings:

Payload size: 10 bytes

Channels: 23, 55, 78

Timeslot period: 600us

Timeslots per channel (in sync): 2

Timeslots per channel (out of sync): default

Sync lifetime: 10

Retransmission attempts: default

Data rate: 2Mbit

Thank you in advance

[Hung Bui]

@lmQ009: In out-of-sync mode, the host remain in one channel for at least 2 timeslot before it's switch to the next one.

This explain why it worked for you when you have 3.6ms = 600us x 2 x 3.

Even with 2 channels you would have trouble with 2.2ms (2.4ms needed). I would suggest you to change the timeslot to 550us and use 2 channels.

[ImQ009]

But can I actually do that? The documentation states that in communication between nRF51 chips using Gazell the minimum supported timeslot is 600us

[Hung Bui]

I know, this is not what we have tested. But I assume with small (10-byte) payload you should be able to get away with 550us timeslot.

Another option is to use just one channel. But then you will have to deal with the interference issue. You can manually do channel hopping then.

Is there any particular reason you need to use Gazell but not using the Radio directly instead ?

[ImQ009]

Yes, after thinking about it I'll propably just use a single channel and implement a different kind of hopping myself. Also, it appears a timeslot of 510us also works well, which is great. And no, there's no reason for me to stick with Gazell. In fact I might use the radio directly.

Thank you for your assistance, it was very helpful