Testing Logic Gates using Arduino

Question

hello guys is there someone who can help me with my first project. its basically about logic circuits.

by using tact switch and pull-up resistor to set the values to logical 1 or 0. the output can be verified by using a LED as an indicator. so the code goes like this:

//AND GATE 
int pin2=1; //set pin2=1
int pin3=1; //set pin3=1
void setup()
{
pinMode(2,INPUT);
pinMode(3,INPUT);
pinMode(4,OUTPUT);
pinMode(11,OUTPUT); 
pinMode(12,OUTPUT);
}
void loop()
{
 pin2=digitalRead(2);
 pin3=digitalRead(3);
 if(pin2==1) //turn led on pin11 when pin2 =1
 {
 digitalWrite(11,HIGH);
 }
 else
 {
 digitalWrite(11,LOW);
 }
 if(pin3==1) ////turn led on pin12 when pin3 =1
 {
 digitalWrite(12,HIGH);
 }
 else
 {
 digitalWrite(12,LOW);
 }
//TRUTH TABLE OF AND 
 if(pin2 && pin3) 
 {
 digitalWrite(4,HIGH);
 }
 else
 {
 digitalWrite(4,LOW);
 }
}
//OR GATE 
int pin2=1;
int pin3=1;
void setup()
{
pinMode(2,INPUT);
pinMode(3,INPUT);
pinMode(4,OUTPUT);
pinMode(11,OUTPUT);
pinMode(12,OUTPUT);
}
void loop()
{
 pin2=digitalRead(2);
 pin3=digitalRead(3);
 if(pin2==1) 
 {
 digitalWrite(11,HIGH);
 }
 else
 {
 digitalWrite(11,LOW);
 }
 if(pin3==1) 
 {
 digitalWrite(12,HIGH);
 }
 else
 {
 digitalWrite(12,LOW);
 }
//TRUTH TABLE OF OR 
 if(pin2 || pin3) 
 {
 digitalWrite(4,HIGH);
 }
 else
 {
 digitalWrite(4,LOW);
 }
}
//NAND GATE 
int pin2=1;
int pin3=1;
void setup()
{
pinMode(2,INPUT);
pinMode(3,INPUT);
pinMode(4,OUTPUT);
pinMode(11,OUTPUT);
pinMode(12,OUTPUT);
}
void loop()
{
 pin2=digitalRead(2);
 pin3=digitalRead(3);
 if(pin2==1) 
 {
 digitalWrite(11,HIGH);
 }
 else
 {
 digitalWrite(11,LOW);
 }
 if(pin3==1) 
 {
 digitalWrite(12,HIGH);
 }
 else
 {
 digitalWrite(12,LOW);
 }
//TRUTH TABLE OF NAND 
 if(!(pin2 && pin3)) 
 {
 digitalWrite(4,HIGH);
 }
 else
 {
 digitalWrite(4,LOW);
 }
}

can you guys help me to run this in one sketch by using tact switch to select the logic gate to be tested or run? thank you in advance

• Edgar Bonet: This cannot work: pin2, pin3, setup() and loop() are all defined three times. You cannot paste three programs one after the other and expect the whole to be a valid program. Just run one program at a time. If you have no push button, use a wire that you manually connect and disconnect to/from GND (if using a pullup resistor) or 5V (if using a pulldown).
• jfpoilpret: @EdgarBonet actually combining both programs in one seems to be the actual question here :-)

Answer 1

What about something like this:

const uint8_t inA = 2;
const uint8_t inB = 3;
const uint8_t outA = 4;
const uint8_t outB = 11;
const uint8_t outY = 12;
const uint8_t button = 5;
void setup() {
 pinMode(inA, INPUT_PULLUP);
 pinMode(inB, INPUT_PULLUP);
 pinMode(outA, OUTPUT);
 pinMode(outB, OUTPUT);
 pinMode(outY, OUTPUT);
 pinMode(button, INPUT_PULLUP);
}
uint32_t check_time = 0;
uint8_t counter = 0;
uint8_t funct = 0b0110; // start with XOR 
void loop() {
 // active low: (for usage with buttons connected to ground with internal pullup)
 // uint8_t state = (digitalRead(inA)==LOW) | (digitalRead(inB)==LOW)<<1;
 // active high:
 uint8_t state = (digitalRead(inA)==HIGH) | (digitalRead(inB)==HIGH)<<1;
 digitalWrite(outA, (state & 1) > 0);
 digitalWrite(outB, (state & 2) > 0);
 digitalWrite(outY, ((funct >> state) & 1) > 0);
 // button handling
 uint32_t actual = millis();
 if (actual > check_time) {
 check_time = actual + 4; // check every 4ms
 if (digitalRead(button) == LOW) { // expects pull-up and active low
 if (++counter == 4) { // debounce - confirmed after 16ms (4*4) and every 256*4 ms again
 funct = (funct + 1) & 0xF;
 }
 } else {
 counter = 0; // reset counter
 }
 }
}

It uses push button to cycle through all 16 possible functions of two inputs. Default is XOR. Assumption is Active HIGH inputs (you can use INPUT instead of INPUT_PULLUP).

Answer 2

For simulating different gates with the same program, an option is to use the serial port to tell it what gate you want it to simulate. Here I am also using a function pointer (called gate) to represent the selected gate:

/* Wiring. */
const int inputA = 2;
const int inputB = 3;
const int outputA = 11;
const int outputB = 12;
const int outputRes = 4;
void setup()
{
 pinMode(inputA, INPUT_PULLUP);
 pinMode(inputB, INPUT_PULLUP);
 pinMode(outputA, OUTPUT);
 pinMode(outputB, OUTPUT); 
 pinMode(outputRes, OUTPUT);
 Serial.begin(9600);
 Serial.println(F("Type 'a'(for AND), 'o' (OR) or 'n' (NAND)."));
}
/* Available gates. */
bool AND(bool a, bool b) { return a && b; }
bool OR(bool a, bool b) { return a || b; }
bool NAND(bool a, bool b) { return !(a && b); }
/* The gate we want to test. */
bool (*gate)(bool a, bool b) = AND;
void loop()
{
 // Select the gate through the serial port.
 switch (Serial.read()) {
 case 'a': gate = AND; Serial.println("AND"); break;
 case 'o': gate = OR; Serial.println("OR"); break;
 case 'n': gate = NAND; Serial.println("NAND"); break;
 }
 // Simulate the gate.
 bool a = !digitalRead(inputA); // input is in negative logic
 bool b = !digitalRead(inputB);
 digitalWrite(outputA, a);
 digitalWrite(outputB, b);
 digitalWrite(outputRes, gate(a, b));
}

Here is another version, that uses an enum instead of a function pointer to identify the gate. The constants and the setup() are the same as before, then:

void loop()
{
 // The gate we want to test.
 static enum { AND, OR, NAND } gate;
 // Select the gate through the serial port.
 switch (Serial.read()) {
 case 'a': gate = AND; Serial.println("AND"); break;
 case 'o': gate = OR; Serial.println("OR"); break;
 case 'n': gate = NAND; Serial.println("NAND"); break;
 }
 // Simulate the gate.
 bool a = !digitalRead(inputA); // input is in negative logic
 bool b = !digitalRead(inputB);
 digitalWrite(outputA, a);
 digitalWrite(outputB, b);
 bool res = false;
 switch (gate) {
 case AND: res = a && b; break;
 case OR: res = a || b; break;
 case NAND: res = !(a && b); break;
 }
 digitalWrite(outputRes, res);
}