Sending over 433 VirtialWire Understanding help

Projects General Guidance
17

That works purely by accident. In the receive code, the variable i is never defined to have any particular value, so the compiler must be initializing it to zero.

Also, in the receive code, it is required to reset the maximum allowed receive buffer length, every time through the loop.

    int i;
...
   if(vw_get_message(buf, &buflen)) // Non-blocking
  {
    Trigger = buf[i];

Try these somewhat simplified examples (not tested) and let me know if it works.

TX:

#include <VirtualWire.h>
char msg = 'B';  //no array necessary for a single character

void setup()
{
    // Initialise the IO and ISR
    vw_set_tx_pin(0);
    vw_set_ptt_inverted(true); // Required for DR3100
    vw_setup(2000); // Bits per sec
}

void loop()
{
    vw_send((uint8_t *)msg, 1);
    vw_wait_tx(); // Wait until the whole message is gone
    delay(200);
}

RX:

#include <VirtualWire.h>

int Trigger = 0;           //Variable for the Received Trigger
uint8_t buf;  //one character buffer
uint8_t buflen = 1;  //buffer length

void setup()
{
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);
  // Initialise the IO and ISR
  vw_set_rx_pin(8);
  vw_set_ptt_inverted(true); // Required for DR3100
  vw_setup(2000);           // Bits per sec
  vw_rx_start();             // Start the receiver PLL running
}

void loop()
{
  buflen=1;  //*** it is required to reset max value of buflen, every iteration of loop ***

if(vw_get_message(buf, &buflen)) // Non-blocking
  {
    Trigger = buf;
    Serial.println(Trigger);
  }
    if(Trigger == 66)     //ASCII for B, 066
    {
      digitalWrite(LED_BUILTIN, HIGH);
    }
   else
   {
     digitalWrite(LED_BUILTIN, LOW);
   }
}