i searched a lot for making a DIY LCD Keypad shield and i found none so i made one and want to share with u guys.

Step 1: Parts Required

a Arduino Uno
16x2 char disply
male and female Header pins
Zero pcb
couple of resistors
a 10k pot (get one solder friendly )
5 push buttons
some small pieces of wires

TOOLS REQUIRED
a cutter (for cutting zero pcb )
a soldering iron
some wire
a wire clipper
thats alll

Step 2: The Theory Part (imp)

The LCD keypad shield use a very clever and neat Technique that is reading buttons from Analog read pin A0

that's a cool thing.

but HOW?

The secret is VOLTAGE DIVIDERS

so what is a voltage divider.

A voltage divider is a simple circuit which turns a large voltage into a smaller one. Using just two series resistors and an input voltage, we can create an output voltage that is a fraction of the input.

yeah i copy pasted it from google ;-)

so now we need to make a voltage divider between 5v and A0 of arduino

and there will be 4 different voltage dividers and each will come to life as we press the button

and that's how we get different inputs at a single pin.

Step 3: THE LIBRARY and RESISTOR CALCULATION

Now we know that how to take inputs

but what value of resistors for voltage dividers we need

our base voltage is 5v.

according to LCD Keypad library written by dzindra on GitHub

the link is:-

https://github.com/dzindra/LCDKeypad

in LCD Keypad.h

// you can change thresholds for detecting key presses

#define KEYPAD_TRESHOLD_NONE 1000

#define KEYPAD_TRESHOLD_RIGHT 50

#define KEYPAD_TRESHOLD_DOWN 380

#define KEYPAD_TRESHOLD_UP 195

#define KEYPAD_TRESHOLD_LEFT 555

#define KEYPAD_TRESHOLD_SELECT 790

so the thresholds hold is analog read of pin A0

accrding to my readings

we need

150k as base resistor (all other are based on it )

250k - select

82k - down

150k- left

15k - up

2 ohm -right

# if you dont have any values u can go slightly up or down because we need to just be in that threshold.

Step 4: Start Making LCD (CONNECTION)

Now grab the parts and resistors you calculated and start making

STEP 1.

cut the zero pcb to the size of Arduino uno

now

STEP 2.

add male headers to board

* the pins connected to lcd are

#define KEYPAD_LCD_PINS 8, 9, 4, 5, 6, 7

mount male headers

Analog pins are good with zero pcb wholes

BUT u need to slightly bend digital pins (to Adjust it)

LCD RS pin to digital pin 08

LCD Enable pin to digital pin 09

LCD D4 pin to digital pin 4

LCD D5 pin to digital pin 5

LCD D6 pin to digital pin 6

LCD D7 pin to digital pin 7

Additionally, wire a 10k pot to +5V and GND, with it's wiper (output) to LCD screens VO pin (pin3). A 220 ohm resistor is used to power back-light and its controlled by pin 10