Week 15

Networking and communications
(May 11)

Assignment:

design and build a wired &/or wireless network connecting at least two processors

1. RF

I want to use these cheap RF transmitter and receiver to communicate between two circuit boards. pin

I use the board for Input Device as a transmitter board. I have already added the RF connection part. For receiver, I use a board I made for Output device The plan is to make transmitter board send the capacitive value to turn on the LED on the receiver board.

2. Programming

First I tried programming without using a library following this tutorial but without success. Then I tried to use Virtual Wire Library following this tutorial and it works well.

Connection of the boards, in the left image is transmitter.

Then I added the capacitive part to turn on the LED on the receiver board.

Here is code for Transmitter :

#include <VirtualWire.h>
#include <CapacitiveSensor.h>
CapacitiveSensor capSensor = CapacitiveSensor (4, 2);
int threshold = 1000;

char *controller;
void setup() {
  pinMode(13, OUTPUT);
  vw_set_ptt_inverted(true); 
  vw_set_tx_pin(12);
  vw_setup(4000);// speed of data transfer Kbps
  Serial.begin(9600); // debug only
}

void loop() {
  
  long capValue = capSensor.capacitiveSensor(30); // capacitive sensor
  Serial.println(capValue);

  if (capValue > threshold || capValue < 0) {
    controller = "1" ;
    vw_send((uint8_t *)controller, strlen(controller));
    vw_wait_tx(); // Wait until the whole message is gone
    digitalWrite(13, 1);

  } else {
    controller = "0"  ;
    vw_send((uint8_t *)controller, strlen(controller));
    vw_wait_tx(); // Wait until the whole message is gone
    digitalWrite(13, 0);
  }
}

Here is code for Receiver :

#include <VirtualWire.h>
void setup()
{
    vw_set_ptt_inverted(true); // Required for DR3100
    vw_set_rx_pin(12);
    vw_setup(4000);  // Bits per sec
    pinMode(13, OUTPUT);

    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
    {
      if(buf[0]=='1'){
   digitalWrite(13,1);
      }  
   if(buf[0]=='0'){
  digitalWrite(13,0);
    }
}
}

Download files :
transmitter (ino)
receiver (ino)

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