Frequency Hopping with NRF24l01+

Since I couldn’t find any frequency hopping example online, I tried one on my own and it works.

For those who don’t know what is Frequency Hopping see this Frequency Hopping  .It is a nice feature for secure communication.FHSS is unhackable (though it also depends on how randomly you change the frequencies )

I have tried Frequency (Channel) Hopping with the Auto Acknowledgement feature of nrf24l01 so that I can change the frequencies on both Tx and Rx devices in synchronism. Sometimes there is a loss of synchronism (possible “different” latencies of the mcus [atmega328p] ).In that case, I manually set them using Serial of Arduino IDE.

In the given example I am sending a 32-byte array of data and hopping linearly between  channels 90 and 125 (back and forth with an increment of 2 ) each new array of data is Transmitted on a different channel (frequency).

Transmitter Code

void loop() /****** LOOP: RUNS CONSTANTLY ******/
{

if ( myRadio1.write( &tx, sizeof(tx) )) {

if (myRadio1.isAckPayloadAvailable())
{
myRadio1.read(&ack, sizeof(ack));
Serial.print(" Transmitted & Ack Recevied for data: ");
for (int j = 0; j < 32; j++) {
Serial.print(ack[j]);
Serial.print(" ");
}
}
for (int j = 0; j < 32; j++)  tx[j]++;  if (flag == 0) {  i += 2;  }  else {  i -= 2;  }  if ((i > 124) && (flag == 0)) {
flag = 1;
}
else if ((i < 90) && (flag == 1)) {
flag = 0;
}

myRadio1.setChannel(i);
Serial.print(" New Channel "); Serial.println(i);

}

if (Serial.available()) {
i = Serial.parseInt();
myRadio1.setChannel(i);
}
}

Receiver Code

void loop()
{
if (myRadio2.available())
{
myRadio2.read( &rx, sizeof(rx));

myRadio2.writeAckPayload(1, &rx, sizeof(rx));

Serial.print(" Data received & Ack sent for data = ");
for (int j = 0; j < 32; j++) {  Serial.print(rx[j]);  Serial.print(" ");  }  if (flag == 0) {  i += 2;  }  else {  i -= 2;  }  if ((i > 124) && (flag == 0)) {
flag = 1;
}
else if ((i < 90) && (flag == 1)) {
flag = 0;
}
myRadio2.setChannel(i);
Serial.print(" New Channel "); Serial.println(i);

}

if (Serial.available()) {
i = Serial.parseInt();
myRadio2.setChannel(i);
}

}

The codes are still not very good. Just an example of FH with Nrf24l01+. Find the full code  (not refined ..still works ) here .Github Here is the demo video :  Youtube