Wireless trigger using RF transmitter/receiver

Projects General Guidance
1

I am pretty new to the Arduino platform and am needing some help making a specific function work.

I'm trying to use some of the inexpensive 433mhz transmitter/receiver pars work as a momentary trigger. So far I have at least been able to make the 2 units talk to each other by using the serial input function and the virtualwire library. This is the code that I used for that.

Transmitter

"#include <VirtualWire.h>

void setup()
{
Serial.begin(9600);

vw_setup(2000);
vw_set_tx_pin(7);
pinMode(13, OUTPUT);
}

void loop()
{
if(Serial.available())
{
char c = Serial.read();

if(c == '1')
{
vw_send((uint8_t *)c, 1);
}
else if(c == '0')
{
vw_send((uint8_t *)c, 1);
}
}
}"

Receiver

"#include <VirtualWire.h>

void setup()
{
pinMode(13,OUTPUT);
digitalWrite(13,LOW);

vw_setup(2000);
vw_set_rx_pin(7);
vw_rx_start();
}

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

if(vw_get_message(buf, &buflen))
{
for(int i = 0;i < buflen;i++)
{
if(buf == '1')

  • {*
  • digitalWrite(13,HIGH);*
  • }*
    _ else if(buf == '0')_
    * {*
    * digitalWrite(13,LOW);*
    * }*
    * }*
    * }*
    }"
    Using this code as a base I then tried to add in a normally closed button with the serial input pullup function. This is the code I used for that.
    Transmitter with button:
    "#include <VirtualWire.h>
    void setup()
    {
    * Serial.begin(9600);*

* vw_setup(2000);
vw_set_tx_pin(7);
pinMode (2, INPUT_PULLUP);
_ pinMode (13, OUTPUT);_
_}_
void loop()
_{_
_ int sensorVal = digitalRead(2);_
_ Serial.println(sensorVal);_
_ if(Serial.available())_
_ {_
_ char c = Serial.read();*_

* if(c == '1')*
* {*
vw_send((uint8_t )c, 1);
_ digitalWrite(13,HIGH);_
_ }_
_ else if(c == '0')_
_ {_
vw_send((uint8_t )c, 1);
_ digitalWrite(13,LOW);_
* }*
* }*
}"
I can't seem to get this setup to function at all. Could somebody please let me know if there is something that I am missing or if you have a better idea. Sorry if the terminology used is wrong. Still getting the hang of all this.
Thanks

2 
char c = Serial.read();
      vw_send((uint8_t *)c, 1);

Casting a char (character) as a char * (character pointer) does not make it so. You will be sending some garbage character.

Also your output depends on serial input, not on the state of the switch. Perhaps was you meant was:

void loop() {
    if(digitalRead(2)) {
      vw_send(("1", 1);
      digitalWrite(13,HIGH);
    } else {
      vw_send("0", 1);
      digitalWrite(13,LOW);
    }
}
3

You read the button state into sensorVal, but don't use it anywhere else in your code.

I think that you should update your code to use sensorVal instead of c. Remember that sensorVal is a digital (boolean) value, not a character. See the code posted by johnwasser.