nRF24L01 Module will only work when connected to computer via USB

@zander Yes, I believe it's just the transmitter. When I use the computer USB connected to the transmitter everything works great. But with my luck I'm guessing when I try it again the receiver won't work this time, but we will have to see. 

I think I am going to try my luck with power banks using AA or 9V. I'm not sure if the 18650's are in my budget especially with the charger. I'm already a little bit over the set budget for this project. I only need the batteries to last maybe 15 minutes as I can swap them out for new ones after each round of our competition.

I appreciate your help, electronics and circuits are by far my least knowledgeable topic and I am definitely going to be working on this over the summer and in my future courses. 

@zander This makes sense, I have also seen a ton of people agreeing with you about the number of knockoffs there are out there.

@jettedlikeshek Ok, sounds like you have the situation under control. The car/receiver is good, the transmitter needs it's own 5VDC power not connected to the NANO, and the NANO can probably work just fine with a single 9V battery on VIN.

NOTE: You could also try first connecting the adapter 5VDC to the NANO +5VDC (pin 27 is output as well) and then use either 2 9V batteries or some other battery arrangement with more life in it.

@jettedlikeshek YEP, learned the hard way and recently scrapped a bunch of fakes. I found a reliable source now but shipping is looooong, like in June.

@zander Yes this sounds like a plan. Thank you again for your help!

Hi @jettedlikeshek,

RE: I am confused as to why this wouldn't be sufficient for the nRf24L01 adapter module. If the LDO regulator takes the 9V down to 5V and provides a steady 5V continuously, why wouldn't it provide a constant 5V to the adapter module as well?

With electricity, you need to consider both voltage (measured in volts) and current (measured in Amps).

For a simple analogy, consider a water flow through pipes and nozzles. The voltage is similar to the pressure of the water, the current is similar to amount of water flowing.

And to complete this picture, electrical power, which is measured in Watts, is product of the voltage and the current for direct current. (Alternating current power is a bit more tricky to calculate, although the principle is the same.)

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From your comment "Based on the Arduino nano datasheet...", I assume you have a 5V Nano.

This effectively has two voltage regulators, but the amount of current that they can supply is limited. The first one, regulates a voltage fed to the Vin pin, in the range 7V-12V down to 5V, and the second is built into FT232RL chip, regulates 5V down to 3.3V.

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In a previous comment, you said that the NRF24L01 worked when power was supplied by USB, but not when power was supplied from the 9V battery. If this is still the case, then I suggest this is because the 7V-12V to 5V regulator cannot supply enough current for both the Nano processor and the NRF24L01 at the same time, and it is protecting itself, by limiting the current flow. This behaviour is mentioned by Bill in his blog. 

I suspect the 9V battery can manage, but its lifetime may be rather short. Check its voltage with a meter. A new alkaline battery will be around 9.5V with no load. If it is below 9V, then it may already be getting exhausted.

5 x AA alkaline cells in series, producing 7.5-8V will last a lot longer than the tiny 9V alkaline batteries, and maybe easier than rechargeables, etc, if you just need to demonstrate a system working for a short time.

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So you need a separate regulator for the NRFL01. (Use Nano 5V for the joysticks). This could be a linear regulator, of which many are available as 3-pin devices, albeit read the data sheet to find out what capacitors are advised. Alternately, you could try of the small buck regulators that are cheaply available on small PCBs, such as the one based on LM2596, as Ron suggested, or you may find a smaller board based on a different chip. Ensure it can provide at least 1A at 5V, and also add a capacitor of about 100 microFarad to the output.

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Best wishes and good luck, Dave

I have an  nRF24L01 that includes a nano on the board along with an ATMEGA328PMU. How can I power this board without the usb cable from the comuter? I have to fit the transmitter in a small space and cannot dedicate a computer to powering it up.  THANKS.

@davida Show pictures of board, link to product. You may have purchased wrong product.

Hi @davida,

  Your board description is somewhat vague, but a quick Google suggests it might be similar to one of the two boards offered at : https://www.aliexpress.com/item/1005007465021204.html

If that is the case then, looking at this advert I can see:

which includes the pins Power Input and GND at the bottom left of the board.

I can also see the text mentions:

 and a photo shows

 Please understand that I do not have any such board to verify the following, but I would expect, you to be able to power the board with a DC voltage in the range 7V-12V applied between the pin Power Input (Positive 7V) and  GND (0V).

The last photo snip shows a chip labelled 1117, which appears to be (or a clone of) the AM1117, which is a voltage regulator capable of withstanding an input of up to 20V, with a recommended maximum of about 12V, which matches the text in the advert.

Please note that depending on the current demand of the rest of the board, this regulator may get too hot if the input voltage is too high. For that reason, it is best to keep in input voltage as close to 7V as possible.

The above method to powering the board is probably the 'safest' approach, but as an experimental alternative, if you have a 5V supply, you might consider connecting it to a matching USB plug, or even wiring to the pins of the USB socket. I am not recommending this method, as it could involve some tricky soldering, and maybe some debugging.

Note, (with any projects like this one), you should always avoid powering the board by the computer and an external supply at the same time. In many circumstances, you will 'get away with it', but if things go wrong, it may damage the board, and a few people have managed to destroy their PC!

Good luck and I hope this helps, Dave

@zander

   Here is the pic.  Thanks

@davee   Thanks for your commets, I believe the center one of your pictures is the one I have.  Now that I look at it with a magnifying glass, I see the Vin which I was missing previously.  Many thanks for your help.    Dave

@davida VIN can be seen for right. If you do not want to use USB then VIN is the only power input pin.

@zander Not sure what you r saying here.  If I program this board with usb (of course) and then power it using Vin and Gnd, will the board operate according to the program?

Thanks, Dave

@davee I just thought of another question. Would the board work if powered by usb from an ac source, like a phone charger, for example?

Dave

@davida Yes and as to your other question, it doesn't matter where the power comes from as long as it is converted to the required 5VDC and can supply up to 5A depending on board being powered. Most of the time a wall wart (phone charger) is used to power via USB.