Which are the *best* NRF24L01+ modules?

[afeno]

@alexsh1

I'm wondering the same as @alexsh1 . How can I get 2.5-2.6V? There is an easy/cheap way to do it?

[AWI]

@afeno The cheap way is a diode in the vcc line. The voltage drop over a normal silicon diode (i.e. 1N4001) is around 0.7V. This has proven to be a working solution.

[parachutesj]

@alexsh1
as it was just a test, I used a table power supply to have the exact voltages.

[afeno]

Hello,
I'm creating a "ping" sketch to measure the % of packet lost using the tmrh20 library. I will post it once it is finished but it is just a modification of the "GettingStarted" sketch.

It is very simple:

• Node 1 send a value to node 2.
• Node 2 receive the message and send it back to node 1.
• Node 1 receive the message.

I'm measuring the number of packets lost and the turnaround time.

But doing some tests, I realised about something very strange that I don't understand...

Based on the sketch described above, both the node 1 and 2 are sending and receiving the same amount of data.
They both use the same commands to send and receive.
I have two hardware sensors/devices (let's call it A and B ) based on arduinos nano.

When I use A as Node 1 it gets 0.2% of packets lost. (B is used as Node 2)
When I use B as Node 1 it gets 15% of packets lost!! (A is used as Node 2)

Remember: Both nodes are sending and receiving the same amount of data.

I understand that the current, radio, noise, etc. might have an impact on the performance and range but why it is working fine on one way? And not in the other way? This is making me crazy. Both sensors are sending and receiving the same data. If one of them is not sending (or receiving) well, the performance still should be the same independent on who is acting as node 1 or 2.

What I am missing?

Thank you!

[NeverDie]

@afeno
Interesting asymmetry.

This sounds basically the same as the sketch I posted earlier. Perhaps post a photo of the two nodes? Maybe something will jump out.

If you really want to solve it, try also
testing the packet loss on the individual links instead of only roundtrip. I suspect it will reveal something.

[afeno]

Sorry for my ignorance... But how can I measure the packets lost on individual links?
Do you mean to check the packets lost in a 1-way trip? Only from node1 to node2?

[cimba007]

Hello,

I thought it might be best to contribute to this thread rather then making a new one. I have some NRF24L01+ for like 2-3 years. Some of them are the normal ones and a few LNA+PA.

The following explanation requires some "advanced" knowledge about the RF24 library and the test-sketch I added. Please forgive me as I was not able to write a more simple sketch and explanation.

From day one I had problems using the modules at 250kbps with autoack. The Reception (RPD) was very poor and I had very high packet loss.

For a few days now I have been tinkering with mysensors and just recently noticed .. wait what???

250kbps + autoack is default.

As mysensors is not ideal for testing modules I used another well known library:

http://tmrh20.github.io/RF24/

To get access to a very important register to debug autoack issues I modified "RF24.h" to get the low level functions public:

**public:**

  /**
   * @name Low-level internal interface.
   *
   *  Protected methods that address the chip directly.  Regular users cannot
   *  ever call these.  They are documented for completeness and for developers who
   *  may want to extend this class.
   */

After that I hooked up an single WS2812B-LED to pin 4 and tinkerd together a little test-sketch:

0_1469476423782_getting_started_250kbps_minimum2.zip

Note: You have to write the values 0 and 1 to EEPROM.Address 0 ONCE. 0 is the static pong back node and 1 is the mobile node with the WS2812B LED. This allows moving freely and check reception in your home.

After writing the values to the eeprom you can comment out the code and don't have to worry when uploading the sketch to the "pongback"-node or the mobile "ping" node.

//EEPROM.write(0,0); // 0 = PongBack

If you don't want to use the WS2812B you have to remove some code but that should not be too hard.

The important parts come now:

settings[autoack] = 0;
settings[retry] = 15;
settings[delay_rf] = 15;

Disabling autoack I could get an improved reading of RDP and very little PacketLoss. I now can cover distanced much larger like through 2-3 walls more then before.

My modules are all powered from 3,3V dedicated LDO or 3V (2x AA) Battery and run @ 8MHz

Long story short:

If you have reception problems even after checking your Supply and even after trying the "ugly fix" and still got nowhere .. i suggest your try disabling auto ack. Although this it not intiutive on mysensors and would leave you vulnerable to packetloss I suggest you to test it out with this library (http://tmrh20.github.io/RF24/) and my example sketch.

Sorry for not presenting a whole solution but I thought it might be worth to point people having reception problems into one possible "direction".

PS: Autoack works fine on my modules if I switch to 1MBPS so this might be viable too.

[gohan]

At current date, is there anybody that can suggest a place to buy good NRF24 modules? I live in Italy so probably US shops would be a little expensive on shipping cost.

[parachutesj]

@gohan
I would not like to make a suggestion and rather reply my opinion on it:
The worst experience I made was with the probably original ones (greenish on reference design). Not that the reception was bad but 4-5 already broke during testing and had to be exchanged.
Therefore I buy the cheapest ones from GC supermarket or other big ALI-shops.
However if you want a amplified version, I would spent the extra dollar and get a premium one. I posted it here somewhere and really made good experiences with it.

[gohan]

@parachutesj

I read your earlier post but after 7 months I was trying to get an update, you know things can change quickly :)

[cimba007]

Just to add my 2cent .. I mainly use the LNA+PA ones (cheap from ebay) and complained some time for their "bad" performance.

Just recently I noticed they are quite nice but .. RF24_PA_MIN is your friend! I got nearly zero packet-loss ~20m (one wall between) with RF24_PA_MIN. This might just be a subjective opinion but as they only cost 2-3$ a piece they are a good option (at least for me).

Getting "genuin" chips for a reasonable price is very difficulty in germany.

[NeverDie]

@cimba007
I think I read somewhere in a different thread on this forum that the PA+LNA ones work better if powered from a lower voltage.

[karlheinz2000]

I ordered modules from ITEAD. They seem to have real nordic chips populated. Each module comes in paper box and ESD bag. The modules look like the cheap ebay stuff, but with 0402 components.
With these modules I got rid of my issue with repeated messages.
(https://forum.mysensors.org/topic/5588/multiple-messages-with-same-content-received)

[gohan]

@karlheinz2000

did you check the chip print if it is genuine or fake? There are some guides if you search. Those modules are quite cheap and that makes me wonder.

[karlheinz2000]

I checked the print and it is different to the cheap ones. But, I got genuine NRF24 chips (just the ICs) from mouser and this print is similar to the cheap ones!!??

Edit:
The print quality of cheap modules is not as good as genuine one and more space between dot and first line.
Genuine parts differ in little dot or square.

ITEAD

IC from Mouser

Cheap Ali/ebay

[gohan]

@karlheinz2000
The first 2 definitely look similar, but the top left logo doesn't look genuine to me. But actually I don't care much about being genuine or not, the import thing is how they perform in terms of reliability and range

[cimba007]

@NeverDie: In addition to using RF24_PA_MIN I power most of my nodes from 2x AA Alkaline Batteries .. so they have 2.2V - 3,0V VCC. This might contribute to my pretty good reception.

Earlier nodes used 3,3V LDO in connection with lithium-ion batteries. So I can't say what really improved my reception the most ... lowering the voltage or putting the RF24_PA_MIN.

[parachutesj]

@gohan @karlheinz2000

just for comparison, my "geniune" has also the same logo and the cheap one looks much "better" but one can see the bad production quality
top one is GC supermarket, bottom genuine

[NeverDie]

@cimba007 said:

@NeverDie: In addition to using RF24_PA_MIN I power most of my nodes from 2x AA Alkaline Batteries .. so they have 2.2V - 3,0V VCC. This might contribute to my pretty good reception.

Earlier nodes used 3,3V LDO in connection with lithium-ion batteries. So I can't say what really improved my reception the most ... lowering the voltage or putting the RF24_PA_MIN.

Anyone know what the optimal voltage range is for running the PA_LNA versions? It would be good to know for future reference.

[NeverDie]

@gohan said:

@karlheinz2000
But actually I don't care much about being genuine or not, the import thing is how they perform in terms of reliability and range

Agreed. And it's not just the chip that will determine that, but rather the entire ball of wax.