Testing 433MHz Transmitter Folks,
There is a document named &quot;Complete Guide for RF 433MHz Transmitter.pdf&quot; available in the GitHub.
There is a a connection diagram showing the Data pin of the Transmitter connected to the pin 12 of the Arduino Uno.
The Transmitter sketch given in it is as follows:
#include &lt;RH_ASK.h&gt;
#include &lt;SPI.h&gt; // Not actually used but needed to compile

RH_ASK driver;

void setup()
{
 Serial.begin(9600); // Debugging only
 if (!driver.init())
 Serial.println(&quot;init failed&quot;);
}

void loop()
{
 const char *msg = &quot;Hello World!&quot;;
 driver.send((uint8_t *)msg, strlen(msg));
 driver.waitPacketSent();
 delay(1000);
}

There is no mention of Pin 12 as part of the sketch. I am not sure how the Arduino knows the Transmitter Data input is connected to the Pin 12? Can someone please help?
Ranjith
In RH_ASK.h is:
RH_ASK(uint16_t speed = 2000, uint8_t rxPin = 11, uint8_t txPin = 12, uint8_t pttPin = 10, bool pttInverted = false);

So the argument has a default value specified here.  If you don't specify it, it assumes that default.