Problem with NRF24L01+PA+LNA (Gateway - Sensor Connection)

  • Hello everyone,

    I have just switched from NRF24L01+ to NRF24L01+PA+LNA radio modules and I am currently struggling with establishing a connection between the Gateway and a Sensor.

    Gateway (NRF24L01+PA+LNA):

    0;255;3;0;9;MCO:BGN:INIT GW,CP=RNNGA--,VER=2.1.1
    0;255;3;0;9;TSM:INIT:TSP OK
    0;255;3;0;9;TSM:INIT:GW MODE
    0;255;3;0;9;MCO:REG:NOT NEEDED
    0;255;3;0;9;MCO:BGN:INIT OK,TSP=1
    0;255;3;0;9;Attempting MQTT connection...
    0;255;3;0;9;MQTT connected
    0;255;3;0;9;Sending message on topic: mygateway1-out/0/255/0/0/18

    Sensor Node (NRF24L01+PA+LNA):

    3 TSM:INIT
    4 TSF:WUR:MS=0
    15 TSF:SID:OK,ID=10
    16 TSM:FPAR
    1615 TSF:MSG:SEND,10-10-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    3627 TSM:FPAR
    3630 TSF:MSG:SEND,10-10-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    5640 TSM:FPAR
    5643 TSF:MSG:SEND,10-10-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    7653 TSM:FPAR
    7656 TSF:MSG:SEND,10-10-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    9664 !TSM:FPAR:FAIL
    9665 TSM:FAIL:CNT=1
    9667 TSM:FAIL:PDT
    19670 TSM:FAIL:RE-INIT

    In general: With the NRF24L01+PA+LNA connected to 3V, the serial monitor remains empty from time to time (especially often if the antenna itself is disconnected from the radio module).

    Also, when starting the Arduino IDE with the sensor node connected, I receive the following error message:

    Error while setting serial port parameters: 115,200 N 8 1

    With the NRF24L01 radio module I used before, there is no such problem. The Gateway receives and the sensor sends - as it is supposed to be.

    It's really frustrating, because I wanted to enhance the signal strength and now I am left with no communication at all. 😳

    I have read that the problem might be the 3.3V supply. Does this problem match the schema?

    Thanks in advance.

  • Mod

    @MaKin yes, power problems is the most common cause. How is it powered?

    Also, it sounds to me like the radio has been operating without the antenna connected, is that right? That might have damaged it. The power amplifier results in a lot of power (as expected). Without the antenna connected, the power has nowhere to go except turn back into the radio module. Not good.

  • Thanks for your help, once again.

    I have only connected it to the Nano's 3.3V port yet.
    Unfortunately, I didn't know that disconnecting the antenna might damage the radio. But I did only try it with one of the radios.

    How should I then connect it properly if the 3.3V is insufficient?

    Thanks in advance.

  • Mod

    @MaKin the 3.3V output for an original Arduino Nano is max 50mA (datasheet page number eight). For a clone it could be different (probably lower to cut cost).

    The nrf24 pa+lna consumes 115mA according to

    So powering from the Nano is not going to work. You need a power supply that can deliver at least 115mA.

  • Don't forget that also a good idea is to throw a capacitor on the power for the radio. I have had decent luck not running one on the regular radios , but when you go up to the power amplified radio I feel it is absolutely necessary. A lot of irregularities can be traced to bad and noisy power.

  • Thanks a lot guys. Can you recommend a suitable power supply? And what capacitator should I get?

    And how does the RFM69 compare to the NRF24L01?

  • Mod

  • Mod

    For a general comparison of rfm69 and nrf24 see

    For power comparison, look at their respective datasheets.

  • Mod

    I use the voltage regulator for nrf24 they have on gearbest. I'm quite happy with it also for the PA modules.

  • It's weird, as it seems to work for my Gateway, but as soon as my sensors are connected with the +PA+LNA, they cannot register. 😞

  • Mod

    You are most likely not supplying enough power for the radio module for transmitting. Also if the radio module is not shielded it could cause problems too if TX power is too high

  • @gohan I bought the voltage regulators for nrf24 and provide 5V, but still...

  • Mod

    which one? what capacitor did you use if any?

  • We bought these: NRF24L01+ PCB Adapter

    We do not use any capacitor.

    What irritates me, the gateway works (ethernet gateway) with the +PA+LNA, whereas the sensor nodes do not. We have switched the PCB Adapters and antennas without any change.

  • Mod

    Ok, try adding one cap on the vcc/gnd pins of the radio: try with a 100uF just to play safe and see if it gets any better, then if it works you could work your way down to a smaller value

  • @gohan Thanks, I will try that!

  • I've also had some issues with these nRF24L01+PA+LNA versions, while not having any issues with the regular nRF24L01 modules.
    I found that if I set the transmitter power (MY_RF24_PA_LEVEL) to a lower setting the problem generally reduced or disappeared completely.
    Of course it is not really nice to use a lower power setting on these modules as it was intended to get maximum range, but it does point in two likely causes:

    • As stated by others, it can be due to poor power at the radio and this must be fixed first:
      1. Make sure to use an adequate external power supply (most arduino's are not up to the task of delivering sufficient current for this type of radio).
      2. Use a (low voltage drop out) regulator near the radio, note that the external power supply delivers sufficient voltage for the regulator to operate correctly.
      3. add a decent size (10~100uF) capacitor near or on the radio's power line
    • At least some of the nRF24+PA+LNA appear sensitive for picking up noise (transmitted by its own antenna). To solve this you will need to shield your radio. The easiest way is if your radio and other parts are in a case and the antenna is sticking out to run to the kitchen and grap the aluminium or tin foil and wrap the entire casing (excluding the antenna) in (multiple layers of) aluminium or tin foil.

    If the latter works (which it did for me), you can look into a cleaner solution of shielding the module (maybe a metal casing?).

  • Mod

    That's why I bought shielded modules

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