Led- 2 pin -brightness of an LED- help

Other Hardware LEDs and Multiplexing
1

hello, I have no pwm pin, use it all.

I can also connect using two digital pins to control the brightness of an LED?

for a 5mm LED, one I put a 10k resitencia,
for another pin, falling to half brightness I put a 20K resistor,
this is good, as this resistance calculation?

int ledA = 7;
int ledB = 4;

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(ledA, OUTPUT); 
  pinMode(ledB, OUTPUT);

  digitalWrite(ledA, LOW);    // turn the LED off by making the voltage LOW
  digitalWrite(ledB, LOW);    // turn the LED off by making the voltage LOW

  
  
}

// the loop routine runs over and over again forever:
void loop() {
  
  for(int i=0;i<2;i++){
  
    if(i==0){
        digitalWrite(ledB, LOW);    // turn the LED off by making the voltage LOW
        digitalWrite(ledA, HIGH);   // turn the LED on (HIGH is the voltage level)
  
    }else{
    
      digitalWrite(ledA, LOW);    // turn the LED off by making the voltage LOW
      digitalWrite(ledB, HIGH);   // turn the LED on (HIGH is the voltage level)

    }
    delay(1000);               // wait for a second

  }
  
}

2

What you have done is make a very simple 2 bit digital to analog convertor. It should work, but instead of using digitalWrite (?, LOW); try pinMode(?, INPUT); and put pinmode(?, OUTPUT); before digitalWrite(?, HIGH);.

If you set one pin HIGH and the other LOW, some current will flow from one pin to the other instead of through the LED.

Paul

3

PaulRB:
What you have done is make a very simple 2 bit digital to analog convertor. It should work, but instead of using digitalWrite (?, LOW); try pinMode(?, INPUT); and put pinmode(?, OUTPUT); before digitalWrite(?, HIGH);.

If you set one pin HIGH and the other LOW, some current will flow from one pin to the other instead of through the LED.

Paul

I do not understand how to do what you mention

4

and using diodes?

5

Yes, those diodes should work.

However, you can do it without diodes like this:

int ledA = 7;
int ledB = 4;

// the setup routine runs once when you press reset:
void setup() {                  
}

// the loop routine runs over and over again forever:
void loop() {
  
  for(int i=0;i<4;i++){
  
    if(bitRead(i, 0) == 1){
        pinMode(ledB, OUTPUT); 
        digitalWrite(ledB, HIGH); 
    }else{
        pinMode(ledB, INPUT); 
    }

    if(bitRead(i, 1) == 1){
        pinMode(ledA, OUTPUT); 
        digitalWrite(ledA, HIGH); 
    }else{
        pinMode(ledA, INPUT); 
    }

    delay(1000);               // wait for a second

  }
  
}

This should give you three levels of brightness (plus off).

However, with 10K and 20K they will be very dim. Try 100R and 220R.