Virtual Wire with simple led on/off

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hello, I am trying to control an arduino using virtual wire and I'm having trouble with my code. My transmitter is connected to the computer and I'm trying to send things like: 'a' or 'b' through the serial. The second arduino should receive these and turn an led on and off. What could be the problem?

Transmitter:

#include <VirtualWire.h>
#undef int
#undef abs
#undef double
#undef float
#undef round

void setup()
{
  Serial.begin(9600);
  Serial.println("Activated");
  vw_set_ptt_inverted(true);
  vw_setup(2000);
  vw_set_tx_pin(13);
}

void loop()
{
  if (Serial.available() > 0)
  {
    char message = Serial.read();
    vw_send((uint8_t *)&message, 1);
    vw_wait_tx();
  }
}

Receiver:

#include <VirtualWire.h>  
#undef int
#undef abs
#undef double
#undef float
#undef round

void setup()
{
  vw_set_ptt_inverted(true);
  vw_setup(2000);
  vw_set_rx_pin(12);
  vw_rx_start();
  pinMode(13, OUTPUT);
}

void loop()
{
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;
  
  if (vw_get_message(buf, &buflen))
  {
    if (buf[buflen] == 'a') {
      digitalWrite(13, HIGH);
    }
    if (buf[buflen] == 'b') {
      digitalWrite(13, LOW);
    }
  }
}
2

On the receiver side, this code is wrong:

   if (buf[buflen] == 'a') {

If buflen equals 1, the value is in buf[0], not buf[1].

3

Ok, I tried:

void loop()
{
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;
  
  if (vw_get_message(buf, &buflen))
  {
    if (buf[0] == 'a') {
      digitalWrite(13, HIGH);
    }
    if (buf[0] == 'b') {
      digitalWrite(13, LOW);
    }
  }
}

It dosen't seem to work.

4

You can also use Serial.begin() and Serial.print() on the receiver, to see whether you are getting any data, and what that data is, if you are getting any.

5

ok, Thanks. I'll try that.

6

Take a look at 4.5 of the manual.
Order is important for some of the calls, you have to move vw_setup.

7

it finally works!

I lowered the rate from 2000 to 1200
so for future reference:

transmitter:

#include <VirtualWire.h>
#undef int
#undef abs
#undef double
#undef float
#undef round

void setup()
{
  Serial.begin(9600);
  Serial.println("Activated");
  vw_set_ptt_inverted(true);
  vw_set_tx_pin(12);
  vw_setup(1200);
}

void loop()
{
  if (Serial.available() > 0)
  {
    char message = Serial.read();
    vw_send((uint8_t *)&message, strlen(&message));
    vw_wait_tx();
  }
}

receiver:

#include <VirtualWire.h>  
#undef int
#undef abs
#undef double
#undef float
#undef round

void setup()
{
  vw_set_ptt_inverted(true);
  vw_set_rx_pin(12);
  vw_setup(1200);
  vw_rx_start();
  pinMode(13, OUTPUT);
}

void loop()
{
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;
  
  if (vw_get_message(buf, &buflen))
  {
    if (buf[0] == 'a') {
      digitalWrite(13, HIGH);
    }
    if (buf[0] == 'b') {
      digitalWrite(13, LOW);
    }
  }
}

thanks all for your help!