Bidirectional Gazell/ESB communication when sometimes only one of the two units is sending packets

RE: Bidirectional Gazell/ESB communication when sometimes only one of the two units is sending packets

Håkon Alseth — Thu, 12 Dec 2024 11:39:19 GMT

Hi,

Thank you for elaborating on your use-case.

If you plan to send a payload every 1 ms, why not use ACK payload for bidirectional communication?

Especially if you have strict timing requirements in under 1 ms, switching the devices manually (ie. not using auto-ACKing) to TX->RX (and vice-versa) for communication will highly likely exceed your timing requirements.

Is there anything I am misunderstanding related to your scenario?

Kind regards,

Håkon

RE: Bidirectional Gazell/ESB communication when sometimes only one of the two units is sending packets

Vince C — Wed, 11 Dec 2024 18:45:24 GMT

I'm expecting the units to be in PRX and PTX state for about an equal amount of time, so 50% of the time in PTX and 50% in PRX.

The units will send packets of about 20 bytes of data. I'm still trying to see what is possible, but hopefully I can get the units to send a packet about every 1ms, and faster if possible.

RE: Bidirectional Gazell/ESB communication when sometimes only one of the two units is sending packets

Håkon Alseth — Mon, 09 Dec 2024 11:57:54 GMT

Hi,

[quote user="Vince C"]I found another discussion online suggesting to put both units in PRX and to switch a unit to PTX only when it needs to transmit something, and then switch it back to PRX.
Do you think that this is a solution that could work?[/quote]

Yes, this is one solution, by manually switching modes.

Keeping the device(s) in the default PRX state is not low power. If your battery powered device switches to "PRX" for a longer period, it will cause quite a high overall current consumption.

How often do you normally send, and how much data do you need to transfer in this "reverted" scenario?

Kind regards,

Håkon

RE: Bidirectional Gazell/ESB communication when sometimes only one of the two units is sending packets

Vince C — Fri, 06 Dec 2024 18:22:03 GMT

Hi Håkon, thanks for your answer.

I would prefer not to send periodic "polling payloads" as this is a battery operated device so I would like to minimize unnecessary communication.

I will try the solution of manually switching between PRX and PTX.

I found another discussion online suggesting to put both units in PRX and to switch a unit to PTX only when it needs to transmit something, and then switch it back to PRX.
Do you think that this is a solution that could work?

RE: Bidirectional Gazell/ESB communication when sometimes only one of the two units is sending packets

Håkon Alseth — Thu, 05 Dec 2024 14:45:01 GMT

Hi,

ESB can send bi-directional packets with the help of ACK payloads, as you mention.

[quote user=""]Is there a way to have both units be able to send packets whenever they need to, no matter if the other unit is sending packets?[/quote]

This will require application specific ESB protocol changes, to manually switch from PRX -> PTX and vice-versa.

One common way of implementing bi-directional communication is to send periodic "polling payloads", but this heavily depends on what your timing requirements and throughput requirements are.

Kind regards,

Håkon