Frequency hopping experiments on the NRF24

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Tobe
Posts: 665
Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Frequency hopping experiments on the NRF24

Post by Tobe »

Have to second Phil as I never had any issues of that character however all my board have the additional capacitors on the power input to the nRF, 100uF Tant and a 100nF on top of the regular decoupling on the 3.3V voltage regulator.
Cheers,

Tobe
John Ryan
Posts: 36
Joined: 31 Mar 2021, 03:56
Location: Rotorua New Zealand

Re: Frequency hopping experiments on the NRF24

Post by John Ryan »

Problems now all sorted. Managed to have a look at the supply rails on a friends scope. With all servos going we found the voltage was dropping up to 1.5v so we tried a 6v battery and every thing ground to a halt. We then hooked up an adjustable power supply and put a volt meter on the 5v output pin and it tracked the input voltage right up to 8v. The regulator is fried. Just bread boarded up another rx with a new nano RF and it works like a charm. Even works without any caps over the input. Magic stuff!
John Ryan
Posts: 36
Joined: 31 Mar 2021, 03:56
Location: Rotorua New Zealand

Re: Frequency hopping experiments on the NRF24

Post by John Ryan »

Phil_G wrote: 17 Aug 2022, 00:25 You've not been running the servos via the Nano's 5v regulator have you John?
All my rxs use a single lipo cell into the 5v input and to servo positives,
ie the 5v regulator has nothing to do, it has no input from vraw :D
Cheers
Phil
Hi Phil
Have been running the servos direct from the battery. Also been back on the scope and discovered the park HPX mini servos in the model really pull the voltage down. We then tried another model with 4 x Futaba 3003 servos and found hardly a ripple on the scope when stiring the sticks. The controls in the HXP model are quite free so they are not overloaded. Not all servos are created equal!
John
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Phil_G
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Re: Frequency hopping experiments on the NRF24

Post by Phil_G »

Sounds like the servos were the culprits John but doesnt explain a blown regulator - maybe just an ELF.
I would be very doubtful of that particular battery. Even your greedy servos shouldnt pull a 4-cell pack down to that extent.
Its all down to equiv series resistance, that pack sounds like it has a high esr. My gliders (Shauns too) are all on a single lipo cell, very low esr
and no discernable drop whatsoever when waggling servos Image
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Mike_K
Posts: 669
Joined: 16 Feb 2018, 06:35
Location: Hertfordshire

Re: Frequency hopping experiments on the NRF24

Post by Mike_K »

I'm late to the nRF24 radio gear party, everybody else is flying with it, I had a dabble when Phil first posted his radio, but I'm only now starting to get to grips with it.

The first thing I decided to do was re-check which of the RF-Nano I had were nRF24L01+ versions and not the older non-plus ones, using Phil's sketch (he describes it as a script).

viewtopic.php?p=8882#p8882

Everything reported a “plus” version, but I realise there's a minor flaw in the sketch as it reported that a standard Nano with no nRF24 was a plus as well…

The problem is that the “plus” version is reported by default, so if the SPI pins are incorrectly configured, there is a faulty nRF24 or if there is no nRF24 at all, it reports a “plus” version. It only reports a “non-plus” if the SPI is configured correctly and it finds a non-plus chip.

After reading through the nRF24 library documentation I found there's a function that checks if the nRF24 is connected (and the SPI is working correctly). Therefore I decided to modify Phil's sketch so that it first checks that the nRF24 is connected properly and only then it checks for the plus/non-plus version. The sketch now correctly reports that the SPI is not working correctly for a standard Nano and a faulty Tstar Techrf-Nano and a “non-plus” for one of the Keywish RF-Nano.

So it’s now a useful check that the nRF24L01+ SPI pins are correctly configured as well as reporting plus/non-plus.
Attachments
nRF24L01_Test.ino
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