NRF24L01+ does not transmit.

[Sergy]

Hi, Im using a module NRF24L01 + LNA bought off ebay, connected it to msp430 via SPI interface. All spi communications are going solid, I manage to completely configure module. Then I try to send some data over the air:

• fill in tx queue
• Write 1 to TX_DS and MAX_RT to clear the flags. (check STATUS gives 0x0E)
• pulse CE for 10uSec

Then Im expecting to get TX_DS set again, however if I check STATUS register i get 0x0E.

So effectively it means nothing is sent out? (I also dont receive anything on the receiver) Any ideas what could go wrong here?

Thanks, Sergey

[Ole Morten]

First a comment that is unrelated to your actual problem: Adding an LNA in front of the nRF24L01+ most often will not give you much range improvement, since the LNA will amplify both the signal and noise, most often giving worse SNR. In addition, blocking characteristics will also be much worse using a LNA because out of band noise can saturate the receiver. If you need better range, adding a PA on the transmitting end is therefore a much better solution.

However, your transmitting sequence seems good. Just to be sure, do you have an nRF24L01+ or nRF24L01? These are two different devices with slightly different feature sets.

If you connect an oscilloscope to VDD_PA, do you see any transitions? This pin should go high each time a packet is sent.

[Sergy]

Hi Ole,

Thanks for the reply. Its an integrated PA+LNA thats installed on that board.

I figured out what the problem was - CE line was not functioning correctly and thats why the 10us pulse didnt work so thats why it didnt update registers.

Now transmit part works, at least according to the registers. But I have also receiving device with pretty much the same initialization code. The only difference is that CONFIG register is set to PRX: 0x0F.

I put device into receiving mode and then in a while loop I check FIFO_STATUS register for RX_EMPTY. And it stays always empty. Any idea what could go wrong there? Did check CE line - its high constantly.

PS I have nRF24L01+

[Ole Morten]

Feel free to post the fact that the CE line wasn't connected as a separate answer, and then accept it as the correct one.

As for your RX problem, have you checked whether the IRQ pin is asserted? I'd normally recommend using the nRF24L01+ in an interrupt driven way instead of polling registers. As you can see in note c to the register map table, the recommended way of handling received data is to "1) read payload through SPI, 2) clear RX_DR IRQ, 3) read FIFO_STATUS to check if there are more payloads available in RX FIFO, 4) if there are more data in RX FIFO, repeat from step 1)."

If you still can't find out anything, posting this as a separate question might make more sense, to separate unrelated things.

[Sergy]

The problem was that CE line wasn't connected correctly - on the MCU it was marked as INPUT, instead of OUTPUT.

[NRF+]

Hi i’m working with NRF24l01+ by avr. but my library don’t work correctly and reset micro suddenly… i cant test my NRF to send and receive my data… plz help me…