Convert ascii to int

Projects Programming
1

Using two Nanos and two RF24L01, I'm sending ultrasonic data from a JSN-SR04T. The Tx serial monitor shows the correct numbers but the Rx shows the asscii value. I have tried several suggestions listed here without success. This is my first attempt to program and surprised I have made it this far. First the Rx then the Tx.

void loop()
{
  
  if (radio.available()) {
 
    char text[32] = "";
    int received;
    
    radio.read(&text, sizeof(text));
      
      lcd.clear();
      lcd.print("Distance= ");     
      //Serial.print(Serial.readString().toInt());
      lcd.print(text);
      Serial.println(text);
      
      delay(500);
}
}



  // Measure distance
  unsigned int distance_cm = sonar.ping_cm();

  // Print distance to Serial Monitor 
  Serial.print("Distance: ");
  
  distance_cm = (distance_cm)*.393701;
  Serial.print(distance_cm);
  Serial.println(" inches");

  // Prepare data to transmit
  int data[sizeof(distance_cm)];
  memcpy(data, &distance_cm, sizeof(distance_cm));

  // Transmit the data
  if (radio.write(data, sizeof(data))) {
    
  }   
 

    delay(500); // Wait for 1/2 second
}
``
void loop() {
  // Measure distance
  unsigned int distance_cm = sonar.ping_cm();

  // Print distance to Serial Monitor 
  Serial.print("Distance: ");
  
  distance_cm = (distance_cm)*.393701;
  Serial.print(distance_cm);
  Serial.println(" inches");

  // Prepare data to transmit
  int data[sizeof(distance_cm)];
  memcpy(data, &distance_cm, sizeof(distance_cm));

  // Transmit the data
  if (radio.write(data, sizeof(data))) {
    
  }   
 

    delay(500); // Wait for 1/2 second
}
2

So what you get with this?

  // Prepare data to transmit
  int data = distance_cm;
  //memcpy(data, &distance_cm, sizeof(distance_cm));

  // Transmit the data
  if (radio.write(data, sizeof(data))) {
3

You need to post the output also in code tags.

4

Check the difference between serial.print and serial.write. You should find: "Serial.print() converts data to a human-readable format (ASCII), while Serial.write() sends raw byte data directly. Using Serial.write() can be faster for transmitting binary data, but the output won't be easily readable in the Serial Monitor."

5

Thank you for your help.
I did try the Serial.write() you suggested but still the same ascii on the receiver end.
Randoman019

6

There are many things wrong with the code you posted.

Better to start with tutorials that have working examples, e.g.

7

The problem is the receiver end.

The data is not being transmitted as text, but your receiver code treats the data as text.

Use the change suggested by @kmin for the transmit code.

Try this for receiver code:

void loop()
{
  
  if (radio.available()) {
 
    //char text[32] = "";
    int received;
    
    radio.read(&received, sizeof(received));
      
    lcd.clear();
    lcd.print("Distance= ");     
    //Serial.print(Serial.readString().toInt());
    lcd.print(received);
    Serial.println(received);
      
    delay(500);
  }
}
1 Like
8

Don't try to read the transmitted value until all the bytes have "crossed the wire"

  int received;
  if (radio.available() >= sizeof(received)) {
    radio.read(&received, sizeof(received));

If you're paranoid, read returns the number of bytes read (past tense) so you can double-check.

9

Hi Paul,
Thank you. Using the (received) was the solution.
Randy

1 Like