rc car / plane control with nRF24L01+

Hello,

Some time ago I made a simple RC transmitter ( uno + nrf24l01+ 2 analog joystics) to control a RC car ( pro micro + l293d + nrf24l01 ).

It was working well, but now I am building rc plane. On transmitter side to increase transmitting distance I've changed nrf24l01 into same chip but with power amplifer + 9db antenna.

On receiver side I'm also using arduino pro micro + nrf24l01+pa, where D3 pin goes to ESC (throttle), D5 and D6 pins are connected to RC plane ailerons.

At a moment this project has some major problems, so there are my questions:

  • is there any need to use nRFl01 + power amplifer in receiver side? (I've set AUTO ACK to 0). transceiver chip without antena will be smaller and lighter
  • Is there a need of additional 5v>3.3 converter on transmitter side? I'm using 3.3v arduino pin, and measured current, RF module consumes not more than ~11 mA

Thank you for advices,

there's how the plane looks like: youtube link

First of all, did you had any distance problems with your first poject?

There is no use in using an power amplifier on the receiver.

What you might need is more power for you transmitting, since the 2.4GHz dipol antennae need a lot of power for solid distance transmitting. Make sure to place your antannae right on plane and transmitter. I place mine horizontal due to the cone of silence. But right away: to achieve a distance more then 250m you might be limited with the transmitting power (germany 25mW). What you could do is using a patch antennae which you have to adjust all the time (I'm making a project for a selfadjusting antennae for my FPV aswell).

Best regards MajorProb

Hi there,

I did test my rc car only indoors, and it worked well. So at a moment I didn't any real distance test yet. On transmitter side i'm using 9dbi ~40 cm omni antenna. Here we do have 100mw limit for a 2.4GHz range, but I measured consumption of my rf module and on peak it eats ~34mw (256 kbps, max amplyfying, 11mA at 3.3v).

Thanks

If you can push it to the 100mW to improve the range. As well as the directing of the RF would help. Or you try a patch antanna with 14 dB. I want to get one myself haven't tried them out yet... Dipol antannae are easy to use and equip but due to the "donut" expansion of the RF it wastes a lot of power.

Best regards MajorProb

Another aspect: If you do this project just for doing it because it's fun, you found a fun thing to do. But if you want a good working system, 2.4GHz transceivers bacame very cheap. I can recommend "Graupner". I use the mz-18 myself and the functions are beyond what you need.

If it is a just for fun project, it is nice for practice :)

Best regards MajorProbs

Hi,

Is there a need of additional 5v>3.3 converter on transmitter side? I'm using 3.3v arduino pin,

If you are using the power amp version in the TX, use a separate 3.3V for the TX, the arduino 3.3V will probably not be able to supply the peak current needed.

Tom... :)

MajorProb:
Another aspect:
If you do this project just for doing it because it’s fun, you found a fun thing to do.

Yes, my rc car project was only for fun, right after it started to work correctly I left it as is and started to work with plane.

I used nrf24l01+ because of cheap price. If there will be not enough of range maybe later i will switch to xbees, hc12 or Lora modules (but they are much more expensive).

I don't have expierience with those modules but sometimes price stands for quality...

Keep me updated on how it goes. :)

Best regards MajorProb

Juokelis: At a moment this project has some major problems, so there are my questions:

  • is there any need to use nRFl01 + power amplifer in receiver side? (I've set AUTO ACK to 0). transceiver chip without antena will be smaller and lighter
  • Is there a need of additional 5v>3.3 converter on transmitter side? I'm using 3.3v arduino pin, and measured current, RF module consumes not more than ~11 mA

I think you need to experiment to find the limits of the range for a Tx with the external antenna and the receiver with the PCB antenna. I had a pair of PCB antennas working outdoors at 110m and they probably would have had a greater range but I was too far away see if the motor they were controlling was rotating. Therefore I guess that the high power Tx would greatly increase the range.

I would certainly use a separate 3.3v supply for the Tx. The last thing you want is a doubt about its reliability. It's not as if the 3.3v regulator is expensive or bulky. Actually I think I would also use a 3.3v regulator on the plane for the receiver.

...R

MajorProb: Keep me updated on how it goes. :)

Today I did test in open field. Unfortunetally here we do not have hills or long open areas, so I find a motorway nearby. I was hearing 17Hz signal for 1500 meters, but was unable to test longer distance. Already at same time I tested my 600mw 5.8 GHz analog fpv transmitter, but was losing a signal very often.

So there is my configuration:

Receiver: 11v 2200 mah battery ESC with 5v 2A regulator arduino pro mini 3.3v regulator based on 1117 chip nRF24l01+pa+lna+sma antenna (I guess antenna is 2 dBi) +10uF capacitor

Transmitter: 7.4v li-po battery arduino uno nRF24l01+pa+lna+sma + 220uF capacitor on 3.3v and gnd 9dBi wireless Omni antenna Edimax

unfortunetally for transmitter side I was unable to use other 3.3v regulator so used arduino 3.3v output. I already ordered few 3.3v regulators but it will take some to get them.

Thanks. That is useful information.

...R