Ultrasonic sensor with 433 mHz radio module problem

Projects General Guidance
1

Hello guys, I am currently making a system which displays the distance of a ultrasonic sensor (HC SR 04 )via a 433 mHz radio module.
When I upload both of my codes, the serial monitor prints numbers like
"E35363132382". It would be awesome if someone can help me out.
Thx in advance.

Transmitter code

#include <VirtualWire.h> //Load the library
#include <SPI.h>
#include <Wire.h>

#define trigPin 10  
#define echoPin 9

float duration, distance;     
char msg[4];


void setup()
{
    vw_set_tx_pin(12);          // Sets pin D12 as the TX pin
    vw_setup(2000);          // Bits per sec
    pinMode(trigPin, OUTPUT); 
    pinMode(echoPin, INPUT); 
    Serial.begin(9600); 
   
}

void loop()
{
     digitalWrite(trigPin, LOW); 
     delay(10); 
    digitalWrite(trigPin, HIGH); 
     delay(10); 
    digitalWrite(trigPin, LOW); 
    
    duration = pulseIn(echoPin, HIGH);
    distance = duration/2/29.1; 
    Serial.print("Distance: "); 
    Serial.println(distance);     
    dtostrf(distance, 6,2,msg);           //converts the float into a char 
    vw_send((uint8_t *)msg, strlen(msg)); //transmits the data
    vw_wait_tx(); // Wait until the whole message is gone
    digitalWrite (12,0);
    delay(200);
 }

RECEIVER CODE

#include <VirtualWire.h>
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>


int i;

void setup()
{
  
  Serial.begin (9600);
  vw_set_rx_pin(12);
  vw_setup(2000);
  vw_rx_start();
}

void loop()
{
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;

  if ( vw_get_message(buf, &buflen) )
  {
   
    for (i = 0; i < buflen; i++)
    {
      Serial.print(buf[i]);         // this is the part where I think it went wrong, the //receiever does receiver data but I think it isnt in the correct type. I am supposed //to get the distance in centimeters, so about couple digits like 123,45 
      

    }

 
  }

}
2

I solved the problem, it is by adding float distance = atoi(strtok((char*)buf, ",")); after the for function in receiver loop.

3

This is another and more serious problem. msg[] can hold only 3 characters, so you are writing to memory that you don't own. Make it larger.

4

would char msg [6] or 7 better ? is that what you mean?

also, thanks

5

You must allocate at least as much space as you ever expect to use. If you don't, your program will crash unpredictably.

6

thank you for your advice

7

Sorry to intertupt, but do u have time to look at another iusse of mine?