VirtualWire - Change tx pin?

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi all-
I have tried my best to figure out how to change the transmit pin value (vw_set_tx_pin()). I am using virtualwire 1.5 library. Everything works fine if I keep the tx out at pin 12 (default), but I cannot get any other output to work. As I will be using 12 for another feature, I really would like to move the tx pin.

There obviously is something I am not doing right.

Here is transmit and receive codes, both working (only on pin 12 of transmitter). You can see where I have commented out the offending (and unworking) reassignment).

I'd really like to move it!!!!

Transmitter

#include <VirtualWire.h>

void setup()
{
pinMode(13, OUTPUT);
vw_setup(2000); // Bits per sec
// extern void vw_set_tx_pin(1); // change tx pin? Won't work???
}
void loop()
{
const char *msg = "NNW 22.0 25.8 25.5"; // A simple
vw_send((uint8_t *)msg, strlen(msg));
digitalWrite(13, HIGH); // set the LED on to show transmitting
delay(40); // wait for a second
digitalWrite(13, LOW); // set the LED off
delay(100);
}

Receiver

#include <VirtualWire.h>
void setup()
{
pinMode(13, OUTPUT);
Serial.begin(9600);
Serial.println("setup");
vw_setup(2000); // Bits per sec
vw_rx_start(); // Start the receiver PLL running
}
void loop()
{
uint8_t buf[VW_MAX_MESSAGE_LEN];
uint8_t buflen = VW_MAX_MESSAGE_LEN;
if (vw_get_message(buf, &buflen)) // Non-blocking
{
int i;
// Message with a good checksum received, dump HEX
Serial.print("Got: ");
for (i = 0; i < buflen; i++)
{
Serial.print(buf*, BYTE);*
_ Serial.print("");_

  • }*
    _ Serial.println("");_
  • digitalWrite(13, HIGH); // set the LED on*
  • delay(40); // wait for a second*
  • digitalWrite(13, LOW); // set the LED off*
  • delay(40);*
  • }*
    }
    [/quote]
2

You have change tx pin to pin 1 which connected to FT232, did you use USB that connected to PC? and you code should be like this, without the "extern void"

#include <VirtualWire.h>

void setup()
{
  pinMode(13, OUTPUT);
  vw_setup(2000); // Bits per sec
  vw_set_tx_pin(1); // change tx pin? Won't work???
}
void loop()
{
const char *msg = "NNW 22.0 25.8 25.5";  // A simple 
vw_send((uint8_t *)msg, strlen(msg));
digitalWrite(13, HIGH);   // set the LED on to show transmitting
    delay(40);              // wait for a second
    digitalWrite(13, LOW);    // set the LED off
delay(100);
}
3

Thanks for the reply, but although it does compile, it doesn't work at any other pin. :frowning:

4

Yes, I forgot, you need to switch the order

#include <VirtualWire.h>

void setup()
{
  pinMode(13, OUTPUT);
  vw_set_tx_pin(1); // change tx pin? Won't work???
  vw_setup(2000); // Bits per sec
}
void loop()
{
const char *msg = "NNW 22.0 25.8 25.5";  // A simple
vw_send((uint8_t *)msg, strlen(msg));
digitalWrite(13, HIGH);   // set the LED on to show transmitting
    delay(40);              // wait for a second
    digitalWrite(13, LOW);    // set the LED off
delay(100);
}
5

Thank you Bill! That was the detail! Now, so that I can learn from this, can you tell me why the order caused that to not work?

6

You have to set the pin first then the setup function will set that pin to the correct input or output.

7

Thanks. Lesson learned. Hopefully, as I absorb more and more of the finer detail, I will be able to help someone else in the future. THANK YOU!

8

Lesson learned on setting vw_set_tx_pin (thanks BillHo!):

For those who may be following this, the devil is in the details. It's important to review the library file when you run into issues like this.

The answer I found is within the comments in the VirtualWire.h file, and qouted below:

  • // Initialise the VirtualWire software, to operate at speed bits per second*
    // Call this one in your setup() after any vw_set_* calls