ESP8266 connecting keypad and lcd display

Question

I have ESP8266 type - enter image description here

I have added a keypad enter image description here

With a standard lcd display.

I have connected the keypad from d0 to d7, however after watching some tutorials i have to connect the lcd display(SDA,SCL) to D0 and D1, where i should connect the display to when they are taken by the keypad?

Answer 1

You can read the keypad using a single analog input (A0 in ESP8266) using this circuit:

keypad resistor array

When you press a key, some resistors are connected between Vcc and Ground. For each key, the total resistence is different, and the voltage at the input pin is different.

To read the keypad, you read the voltage at the input pin A0. You also have a table that associate the readings with keys. You search in the table for the nearest entry to the value you get. That's your key.

Wire the circuit and make a little sketch to read the values for each key you press. That's how you construct your table.

The value at A0 will be a little different each time you read the pin. That's is normal. Don't expect a exact macht.

• IMAN4K: This won't work! the ADC of ESP is in range 0.0-1.0v!