Do different NRF24 modules behave differently?

Hi all,

I have designed a stand alone arduino compatible system based on the ATMEGA32U4 micro which now behaves just like an Arduino micro. The system was tested with a basic nrf24 module like this one and works fine.

However, when the module above was replaced with the amplified version with external antenna (like this), nothing works. Not only comms fail, but the sketch freezes. When the original module is replaced, everything is fine again. I have tried this with two different amplified modules and the result is the same.

Can anybody think of any reason why one module is working and the other is not ?

Thanks

Receiver overload. Set the power level to the minimum and separate the two modules. I have seen overload problems with two of the low power versions. Depending on how you are powering the PA version, you may have voltage sag problems.

Receiver overload. Set the power level to the minimum and separate the two modules. I have seen overload problems with two of the low power versions. Depending on how you are powering the PA version, you may have voltage sag problems.

I ve tried that already!.... the PA level is at LOW... they are about 3m apart... the remote module is a the non-powered version.

There is an on-board dedicated 3.3v regulator for the PA module.

However what really puzzles me is not so much that comms fail but the fact that program freezes as well. (the one with the PA module)

I've had the program lock up when the module could not be read. The only other idea I could offer is to replace the PA module antenna with a dummy load, or high value attenuator 9dB or greater, as there should be enough leakage from the PCB traces to still work. If you use an attenuator and need some signal, put a 1.2" piece of wire into the output side. Also, try another module as you may have a two bad ones, not likely though.

If you do not have a very solid 3.3V supply, the high power module will not work.
The standard modules get along with less peek current.

If you do not have a very solid 3.3V supply, the high power module will not work.
The standard modules get along with less peek current.

Would this also explain the fact that the sketch freezes probably even before it reaches the main loop?

The module is powered by a dedicated AMS1117 3.3 regulator located at about 1cm from the modules pin header.An additional 47uF cap is soldered on the pin header itself. Would you say this constitutes a "solid" power supply?

Thanks for your input...

It depends where the AMS1117 is attached to. Is that supply capable of delivering the needed input?
You could make shure that there is no problem with the supply by using an oscilloscope.

The capacitor should work, but it should go as near to the chip as possible (I attach it to the pins of the modules).

Weak supplies normally allow some reception and fail at most transmissions.

The thing is, the sketch freezes even with no transmission…

Update: Disabled all transmit functions and the sketch no longer freezes.

Apparently everything freezes the first time it tries to transmit something.

I have also connected a scope on the 3.3v supply rail on the modules pin header and the supply remains at 3.286V when it tries to transmit. Hence I guess this is not a power supply issue.

I am running out of ideas here...

IS this a case of faulty modules? Both of them faulty ??

Good chance if you bought them at the same time from the same seller. Their stock may be from the manufacturer’s single lot number. Buy another one from somebody else.

ok… I ve just ordered another pair… will take for ever to arrive :frowning:

There is another thing that I am also considering…

Referring to the picture below the nrf module is located directly above the CPU. Could it be the case that this higher power module interferes with the cpu during transmission and hence causes everything to freeze?

Is this a case of EMC problems?

Yes, that's possible as the antenna is trying to use the traces on the board as a ground plane. Try using an attenuator or dummy load in place of the antenna.

I dont anything like that am afraid...unless you mean just a resistor..

If you use a 47R or 51R resistor, you must keep the leads as short as possible. At that frequency, almost any length of wire becomes part of the antenna.

Check eBay for SMA 9dB attenuators. They make good dummy loads and with a short wire stuck in the far end, you have a slight amount of radiation for short range testing.