ESP8266 un useable pins

Projects General Guidance
21

okay thats okay for this project. you had me scared. thanks for the information tho. i had made a program to check the pins on my board. this is what i came up with. i even tested pulling them low and high and rebooting to see what would happen,

void setup() {
  pinMode(35,OUTPUT); //// NOT USEABLE AS OUTPUT //float sensor 2
pinMode(34,OUTPUT); // NOT USEABLE AS OUTPUT //float sensor 1
pinMode(33,OUTPUT); //relay1
pinMode(32,OUTPUT); //relay2
pinMode(27,OUTPUT);//adc2
pinMode(26,OUTPUT);//adc2
pinMode(25,OUTPUT);//adc2
pinMode(23,OUTPUT); //relay3
pinMode(22,OUTPUT);//rtc
pinMode(21,OUTPUT);//rtc
pinMode(19,OUTPUT); //relay4
pinMode(18,OUTPUT); //flow sensor
pinMode(15,OUTPUT);//adc2
pinMode(14,OUTPUT);//adc2
pinMode(13,OUTPUT);//adc2
pinMode(12,OUTPUT); //CANNOT BE PULLED HIGH AT STARTUP //adc2
pinMode(5,OUTPUT);
pinMode(4,OUTPUT); //adc2
pinMode(2,OUTPUT); //BUILT IN LED //adc2
}

void loop() {
  digitalWrite(35,LOW);
digitalWrite(34,LOW);
digitalWrite(33,LOW);
digitalWrite(32,LOW);
digitalWrite(27,LOW);
digitalWrite(26,LOW);
digitalWrite(25,LOW);
digitalWrite(23,LOW);
digitalWrite(22,LOW);
digitalWrite(21,LOW);
digitalWrite(19,LOW);
digitalWrite(18,LOW);
digitalWrite(15,LOW);
digitalWrite(14,LOW);
digitalWrite(13,LOW);
digitalWrite(12,LOW); 
digitalWrite(5,LOW);
digitalWrite(4,LOW);
digitalWrite(2,LOW);
delay(200);
digitalWrite(35,HIGH);
digitalWrite(34,HIGH);
digitalWrite(33,HIGH);
digitalWrite(32,HIGH);
digitalWrite(27,HIGH);
digitalWrite(26,HIGH);
digitalWrite(25,HIGH);
digitalWrite(23,HIGH);
digitalWrite(22,HIGH);
digitalWrite(21,HIGH);
digitalWrite(19,HIGH);
digitalWrite(18,HIGH);
digitalWrite(15,HIGH);
digitalWrite(14,HIGH);
digitalWrite(13,HIGH);
digitalWrite(12,HIGH);
digitalWrite(5,HIGH);
digitalWrite(4,HIGH);
digitalWrite(2,HIGH);
delay(200);
}
22

I had myself scared as well. Thank you for your help to correct it :smiley:

Please don't set 34 and 35 as digital output. On some boards they are not even available.

Sometimes D2 is for the led and sometimes D5 is the led. You probably can use LED_BUILTIN which should be the right pin number when the right board is selected.

23

Not really.

Not for outputs, unless you only ever want to activate one at a time.

Useful for inputs, though you need three control pins and an input pin to control a 74HC4051 (four and an input pin for a 74HC4067) so unless you are going to use a multiplexer for more than four inputs, it is a waste of time.

More to the point would be an I2C port expander.

24

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