Checking for carrier with nRF24L01+

[psdeering]

Hi all,

Is it possible to check whether there is an active carrier with the nRF24L01+? I've got the TX and RX chips configured via SPI correctly (I think), yet I can't send / receive between the two. So I'm not sure whether the TX is actually transmitting anything across the air. At $20k, a spectrum analyser is out of the question, so it would be extremely handy if the RX could query whether there is an active carrier.

There seems to be a RPD register (Receive Power Detector), with a CD bit. Is it legitimate to start a continuous carrier on the TX, and then poll the CD bit on the RX? This would be extremely handy if this is a legitimate way of checking for an active carrier.

Or are there some hidden debug registers on the nRF that can be used to query this information?

Regards, Paul

[Kenneth]

Hi Paul,

In general you might get some help on how to setup the nRF24L01+ in different operational modes by looking at this application note: Software examples using ShockBurst modes in nRF24L01 and nRF24LU1

To answer your question, you can measure that you have a transmission by measure on the VDD_PA pin, the VDD_PA pin will go high (~1.8V) on every transmission, each transmission will last a few hundred us depending on datarate and packet size.

To find if the chip is in receive mode the easiest is really to measure the current consumption, it should be >10mA in receive mode.

If nothing else works, make sure to read out all registers and compare them. Toggle CE high in transmit mode should start a transmission, unless the MAX_RT bit is set (that needs to be cleared). On the receiver the CE can be held high continously once configured to RX mode.

Best regards, Kenneth