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Multiplexing with the Arduino

Mulitplexing

This is multiplexing

Resources

• http://www.arduino.cc/playground/Learning/4051
• Instructions from Arduino Playground
• Go to 'multiplex' and 'multiplexing' here.
• Image of set up
• The relevant part:
  4051 analog multiplexer/demultiplexer -
  Rapid:
  4051BM 8 CHANNEL MULTIPLEXER SO-16 (TI) part number 83-0289
  4051B ANALOGUE MULTIPLEXER/DEMULT (RC) 83-0384

Code

/*
 * codeexample for useing a 4051 * analog multiplexer / demultiplexer
 * by david c. and tomek n.* for k3 / malms hsgskola
 * modifications by Richard Hoadley
 * rhoadley.net
 *
 */  

int led = 13;    // LED (not necessary)
int r0 = 0;      // value select pin at the 4051 (s0)
int r1 = 0;      // value select pin at the 4051 (s1)
int r2 = 0;      // value select pin at the 4051 (s2)
int row = 0;     // storing the bin code
int count = 0;    // just a count
int  bin [] = {000, 1, 10, 11, 100, 101, 110, 111};// bin = binary value
int val = 0;

void setup(){

  pinMode(2, OUTPUT);    // s0
  pinMode(3, OUTPUT);    // s1
  pinMode(4, OUTPUT);    // s2
  digitalWrite(led, HIGH); 
  Serial.begin(9600);
}

void loop () {

  for (count=0; count<=7; count++) {
    row = bin[count];      
    r0 = row & 0x01;
    r1 = (row>>1) & 0x01;
    r2 = (row>>2) & 0x01;
    digitalWrite(2, r0);
    digitalWrite(3, r1);
    digitalWrite(4, r2);    
    // Serial.println(bin[count]);

    
    if ( bin[count] == 0 )
      {
        // Serial.println("true");
        val = analogRead(0);
        Serial.print("y0: ");
        Serial.println(val);
      };
      
    if ( bin[count] == 11 )
      {
        // Serial.println("true");
        val = analogRead(0);
        Serial.print("y3: ");
        Serial.println(val);
      };
      
    delay (10);
  }  // end of for
  
} // end of loop

To Cover

• Multiplexing and demultiplexing
• Uses
• Other uses (e.g. Teabox, audio interfaces, Madrona Labs, etc.)
• Disadvantages

Ramifications

• Using many more than the normal range of inputs and outputs from the Arduino, but not without some cost to responsiveness under some circumstances.

You might also be interested in:

• Other Arduino Tutorials.

The Projects

The projects and tasks are designed to help you through the various courses and materials that you'll have to deal with, and also to provide an active and practical element to what could otherwise become a rather dry and technical exercise. Tasks are small exercises - you may be asked to complete one or two per week. Projects are larger and carry a higher percentage of the mark. We will undertake two, three, four or more projects and tasks. The final project is usually an individual choice project, and will be worth significantly more than the others in terms of percentages in your portfolio. We will usually try to set aside a time to perform the projects in a public setting.