NRF24l01 Channel switching

Question

I have a NRF24L01 radio module. The description indicates that it can work in the ISM frequency range of 2.400 ... 2.525 GHz. The channel step is 1 MHz, and there are 125 channels in total.

The channel number can be set using radio.setChannel (0x125); The maximum number is supposedly 125. However, I examined the signal spectrum in Sdrsharp using a radio tuner and it turned out that the frequency at the maximum channel is very low.

I started increasing the number and got to 180 radio.setChannel (125); the frequency was 2525 MHz as stated. It turns out that the number of channels of the radio module is not 125, but 180? I determined the 180 number experimentally. The literature says that it has 125 channels 1 MHz wide. The most interesting thing is that the Arduino IDE does not give errors when entering a large number of channels. Tell me how you can speed up the process of switching channels in order to understand how they switch. To manually reflash it for a long time when changing each channel.

#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"

RF24 radio(9, 10); // use 9 и 10 pin arduino uno
byte address[][6] = {"1Node", "2Node", "3Node", "4Node", "5Node", "6Node"}; 
byte counter = 1;

void setup() {
  Serial.begin(9600); 

  radio.begin(); //activate module
  radio.setAutoAck(0); //confirmation mode, 1 on 0 off
  radio.setRetries(0, 15); //(time between attempts to reach out, number of attempts)

  radio.setPayloadSize(32); //packet size, in bytes

  radio.openWritingPipe(address[0]); //we are pipe 0, we open a data channel
  radio.setChannel(125); //select a channel (in which there is no noise!) 0 ... 125

  radio.setPALevel (RF24_PA_MIN); //transmitter power level. To choose RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH, RF24_PA_MAX
  radio.setDataRate (RF24_2MBPS); //exchange rate. To choose RF24_2MBPS, RF24_1MBPS, RF24_250KBPS
  radio.powerUp(); //get started
  radio.stopListening(); //do not listen to radio broadcasts, we are a transmitter
}

void loop(void) {
  while (1)
  {
    radio.write(&counter, 1);
    //Serial.println(counter);
  }
}

Is it possible to toggle the channel number radio.setChannel (0x180) sequentially in a void loop? thanks!

I tried to do this:

void loop (void) {
     for (int n = 0; n <126; n ++)
     {
       radio.setChannel (n); // select a channel (in which there is no noise!) 0 ... 125
       radio.write (& counter, 1);
       delay (1000);
     }
}

However, radio.write (& counter, 1) should work separately from any loops to avoid delays. Otherwise, it doesn't work correctly.

Answer 1

You're getting confused with number bases. A number prefixed with 0x is hexadecimal. That's base 16 - not base 10.

0x125 is actually 293. If you try squeezing 293 into an 8-bit register it will truncate to 37.

Channel 125 is 0x7D in hexadecimal.

I can't recall off hand how big the register is for the channel number, but either 7 or 8 bits would suffice (probably only 7 bits actually used) so the highest channel number you could possibly enter would be 127, which is 0x7F, after which it will start at channel 0 again for 128 or 0x80.