Zigbee TXPOWER change issue.

[embedded_noob]

Hi,

I am trying to change the tx power of Zigbee using the following APIs : 

1) zb_set_tx_power(0x32);
2) nrf_radio_txpower_set(NRF_RADIO_TXPOWER_NEG12DBM);
3) nrf_802154_tx_power_set(NRF_RADIO_TXPOWER_NEG12DBM);

None of this API makes a significant change in the TXPOWER CPU register and similarly I cannot see any change in the Wireshark RSS. Can you suggest a proper API to see the changes in TXPOWER.

Thanks

[embedded_noob]

Hi,

I saw your post we have the same sniffer. I am trying to use -12, -20 and 0 dBm.

In the menu of Wireshark just on the side of nrf sniffer 802.15.4 you will find a setting icon clicking on it will let you select the IEEE TAP please look at the image after adding this you can see the RSS in your Wireshark.

[Edvin]

Thanks for the guide. I usually use the dongle, so if I have already set the channel, this window doesn't pop up again. Tried to sniff with a DK, and the window popped up.

So what I see when I switch between +8 and -40 on the light bulb is that the RSS on the sniffer changes. But there are two ACKs from the lightbulb. One will use the RSSI that I set, while the other one is quite steady around -35 on the sniffer (so I guess it is 0 when transmitted). 

You never mentioned what you saw on your sniffer? From your sniffer trace (with_power_change). What device is it that changes the TX power, and between what packets do you do it?

[Edvin]

Upon further inspection of the log, I see that the second message, which had RSS= -35 is coming from the coordinator, which I didn't change the TX power on. So the TX power is successfully changed.

Please see the following screenshot:

I am sorry, but my wireshark keeps crashing when I try to save a capture, so I can't save the sniffer trace.

Did you try to set it to -40? And when you claim it doesn't change, can you check the extended source, and verify that it is indeed from the device of which you changed the output power?

BR,

Edvin

[embedded_noob]

Yeah it try to set -40 but by default in the WIreshark it was showing the value around -35 dBm so we cannot figure it out it changed or not. As you mentioned that the by default the code starts at 8 dBm I never saw RSS in positive. I used ZC power default and ZED power was changed by adding a CLI command. 

[Edvin]

The RSS should start at the effect that you set, but naturally, the signal strength will drop when the packet is received, because of noise and effect loss both at the transmitting antenna, receiving antenna, and the distance between the devices. However, if you set the output power to -40, you should never see the RSS of -35, because it is not possible that the signal strength has increased over the air. Again, can you double check that the extended device address is actually the device that you changed the TX power on, and that it is not another node routing the message to the receiver? The extended network address is part of the packet. If you still claim that it is not changing, do you have a project where it doesn't work, and I can replicate it? Because I tried it in the light bulb example, and it worked there.

Best regards,

Edvin