Arduino uno receiving message and calculating distance

[mzhgna]

I am planning to let an ATTiny85 to:

1. Send a message to an Arduino Uno by 315MHz module and VirtualWire
2. Send a pulse to SR04
3. If receive a pulse, then send a message to the Arduino Uno.

Code for ATTiny85:

#include <VirtualWire.h>

#define TRIG 2
#define MSG  4
#define ECHO A3

void setup() {
  // put your setup code here, to run once:
  vw_setup(1000);
  pinMode(ECHO,INPUT);
  pinMode(MSG,OUTPUT);
  pinMode(TRIG,OUTPUT);
  vw_set_tx_pin(MSG);
}

void loop() {
  // put your main code here, to run repeatedly:
  send("T1");
  digitalWrite(TRIG,LOW);
  delay(1000);
  digitalWrite(TRIG,HIGH);
  delay(200);
  digitalWrite(TRIG,LOW);
  if (digitalRead(ECHO) == HIGH)
  {
    send("0");
  }
  delay(10000);
}

void send (char *message)
{
vw_send((uint8_t *)message, strlen(message));
vw_wait_tx(); // Wait until the whole message is gone
}

But the Attiny isn't sending 0, just "T1". Where could be the problem?

[jremington]

@mzhgna

  if (digitalRead(ECHO) == HIGH)
  {
    send("0");
  }

This all happens long before the ECHO pin goes high, then the processor does nothing for 10 seconds.

[qubits-us]

Delays are way too long and you should be using pulseIn..
Check this..
ultrasonic sensor demo..

good luck.. ~q