Zigbee TXPOWER change issue.

RE: Zigbee TXPOWER change issue.

LangSQ — Fri, 22 Jan 2021 07:19:54 GMT

Hi,

I got a same question about TX power increasing to +8dBm for nRF52840 in zigbee mode.

1、Before reseting power value,call this function `nrf_802154_tx_power_get()`,results is 0 and `my_tx_power_register` is 0x00000000.

2、Reseting power value 8 by calling this function `nrf_802154_tx_power_set(8)`,and call `nrf_802154_tx_power_get()`,the result is 8,but the `my_tx_power_register` still is 0x00000000

It can be seen from this,if call `nrf_802154_tx_power_set()` can get changed TX power value by call `nrf_802154_tx_power_get()`,but the `my_tx_power_register` is same,why?

This is part of power reset vaule code:

NRF_LOG_INFO("Get TX Power Before Reseting:  %d", nrf_802154_tx_power_get());
NRF_LOG_INFO("Register Valuse Before Reseting: 0x%08x", NRF_RADIO->TXPOWER);  // The actual value from the register
nrf_802154_tx_power_set(TX_POWER_LEVEL);
NRF_LOG_INFO("Get TX Power After Reseting:  %d", nrf_802154_tx_power_get());
NRF_LOG_INFO("Register Valuse After Reseting: 0x%08x", NRF_RADIO->TXPOWER);

Thanks

RE: Zigbee TXPOWER change issue.

embedded_noob — Tue, 11 Aug 2020 13:11:27 GMT

Ok got it. I will try it again and make sure everything works.

Thanks for your help.

RE: Zigbee TXPOWER change issue.

Edvin — Tue, 11 Aug 2020 09:04:40 GMT

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

RE: Zigbee TXPOWER change issue.

embedded_noob — Mon, 10 Aug 2020 13:30:30 GMT

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.

RE: Zigbee TXPOWER change issue.

Edvin — Mon, 10 Aug 2020 12:41:06 GMT

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

RE: Zigbee TXPOWER change issue.

Edvin — Mon, 10 Aug 2020 08:30:53 GMT

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?

RE: Zigbee TXPOWER change issue.

embedded_noob — Fri, 07 Aug 2020 14:54:09 GMT

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.

RE: Zigbee TXPOWER change issue.

Edvin — Fri, 07 Aug 2020 14:07:40 GMT

I suspect we are not using the same sniffer:

So what are the TX powers you are trying to use? Did you try +8 and -40 dBm?

RE: Zigbee TXPOWER change issue.

embedded_noob — Wed, 05 Aug 2020 14:14:35 GMT

When you configure the nRF Sniffer in the setting right besides it you can change the channel and there is one more drop down for IEEE 802.15.4 TAP please select that it will show the RSS information. I have attached the wireshark caputre files before and after changing the power. Please have look.devzone.nordicsemi.com/.../Capture_5F00_With_5F00_Power_5F00_Change.pcapng devzone.nordicsemi.com/.../Capture_5F00_WO_5F00_Power_5F00_Change.pcapng

In the Image file you can see that I am setting the power and checking it with the same command the code is just besides the terminal window. But still I cannot see change in power.

The using a custom get data cmd I am sending 10 bytes of packet 2 times and sending at interval of 5 seconds.

get data [payload_size] [#to send] [Timer Interval] [True].

You can see the commands being Transmitted in the wireshark with and without power change.

RE: Zigbee TXPOWER change issue.

Edvin — Wed, 05 Aug 2020 12:05:56 GMT

Do you see the RSSI of packets in wireshark (because I can't see it when I use the sniffer).

I use a couple of methods to check the TX power. I use nrf_802154_tx_power_get() to read the TX power from the radio driver, and then I read the TX power register using:

uint32_t my_tx_power_register = NRF_RADIO->TX_POWER;
NRF_LOG_INFO("my_tx_power_register: 0x%08x", my_tx_power_register);

To print the actual value from the register.

Then I use the button handler (with some unused buttons) to trigger nrf_802154_tx_power_set() and print the values from the register. I see that sometimes it may take some time before the register updates, but I am fairly sure that this is only because the changes doesn't take effect before the radio is actually going to transmit something.

So can you describe to me how you change, and what you see in wireshark? You may not see the difference between 0 and -12, but perhaps you can try some more extreme values and see if you see any change in the RSSI. E.g. +8dBm vs -40dBm. Can you show a screenshot of what the RSSI looks like on wireshark?

Best regards,

Edvin

RE: Zigbee TXPOWER change issue.

embedded_noob — Tue, 04 Aug 2020 13:45:30 GMT

Thanks for the reply.

I tried changing the TX power of the ZC so It was network creator. So basically does the nrf_802154_tx_power_set() should be used before the stack is initialized?. Additionally I can see the value getting set to value I set using the above API but cannot see the change in the Wireshark.

Thanks

RE: Zigbee TXPOWER change issue.

Edvin — Tue, 04 Aug 2020 10:33:46 GMT

Hello,

I see that the zigbee stack will change the TX power back to 8dBm as long as the device is not part of a network. If you join a network, I could use the functions nrf_802154_tx_power_set() and nrf_802154_tx_power_get() to change the TX power (and confirm it). Was the node part of a network when you tried to use nrf_802154_tx_power_set()?

BR,

Edvin