Reading the buttons and features of LCD Keypad Shield

The sainsmart LCD Keypad Shield has a handy 16-character by 2-line display, 5 buttons and a controllable backlight, plug it straight in on top of your Arduino controller boards. The display is set behind the shield for a low profile fitment and nice look and we've included panel mounting screw holes in the corners.

The buttons provide "left", "right", "up", "down", and "select" while using just one analog input. That leaves the other analog inputs free for you to use in your projects.
A0, using a chain of resistors that causes a different reference voltage to be applied to A0 depending on which button is pressed.If no button is being pressed,the voltage on A0 will be pulled all the way up to 5V by the 2K resistor called R6. In that situation none of the other resistors have any effect at all, and the analog reading on A0 will be hard on the upper limit of 1023. Therefore if you perform an analogRead() call on A0 and it returns 1023 (or any value above about 1000) you know that no buttons are being pressed.
The same principle is also applies for the other buttons.
Features:
16x2 LCD using HD44780-compatible display module
5 buttons on one analog input
LCD backlight with current limiting, brightness and on/off controllable by D3, can be moved to a number of other pins for easy project pin compatibility
Recessed LCD, panel mount screwholes and button layout suitable for panel or cabinet mounting if desired.
Reset button
Power supply smoothing capacitor
Gold-plated PCB for maximum durability
Overlay printed on both top and bottom
Pins used by shield clearly marked, LiquidCrystal library setup reference is on the bottom of the pcb for convenience.
Overlay printed on both top and bottom
Pins used by shield clearly marked, LiquidCrystal library setup reference is on the bottom of the pcb for convenience.

High or low, it's up to you

By using the sainsmart LCD Keypad Shield,we can control the intensity of the backlight with the Arduino digital pin D3.That is to say,the backlight will become on and off if you set the pin D3 high or low.It's up to you.
First of all,we can Vary Backlight Intensity:

Generally speaking,We choose pin which is capable of "PWM",to control the backlight. such as Arduino pin D3. Using PWM you can vary the intensity of the backlight by setting pin D3 to different levels between 0% and 100% using the analogWrite() function.
If you want to combine the sainsmart LCD Keypad Shield with another shield which also uses Arduino pin D3, you may want to change the backlight control over to another Arduino pin. Fortunately,the shield is designed to make this easy to do.
The pair of pads labelled "D3" is connected on the PCB by a tiny track which you can easily see, so the first step is to use a sharp knife to cut the track between the two pads.
Now that you've disconnected Arduino pin D3 from the backlight control, you can either leave the backlight control disconnected entirely (in which case it will be permanently on) or connect it to a different pin using one of the other pairs of jumpers.
Pick the pin you want to use to control the backlight, please remember that not all pins can do PWM,so you may only be able to turn the backlight on or off rather than vary its brightness, and connect those pads by using a drop of solder.

You deserve a perfect LCD Contrast

This is a guide to adjusting LCD Contrast for your sainsmart LCD Keypad Shield. It also can be used to other type LCDs in Arduino projects.

The sainsmart LCD Keypad Shield uses a standard alphanumeric type LCD which has a contrast pin can be adjusted by the area designed into the top right corner of the board.
The LCD contrast can be made higher by setting the contrast pin to a lower voltage.
If your board has R1 on it (a 10K pullup), simply remove R1 with a soldering iron to do this. This is especially useful in colder temperatures or with lower voltage levels into the 5V pin of the board.

Fine adjustment:

Very fine adjustment isn't usually needed because our LCDs are a wide temperature range type, if you really want to fine adjust your LCD contrast voltage there are two solutions:
The one is to change the R1 and R10 resistor values to set your desired LCD contrast voltage. R1 and R10 form a common resistor divider to set the LCD contrast voltage into the display.
The other way is toplace a 10K trimpot onto the VR1 footprint, removing R1 and R10, then adjust the VR1 trimpot to any desired contrast setting. You have an optional footprint to accept most common surface mount 10K trimpots like the Bourns 3314J type.
If your LCD contrast is still weak and R1 is already removed, check the voltage at the 5V pin into the LCD Keypad Shield. Sometimes the 5V rail can be low from a weak USB port or cable source (less than around 4.6V) and the LCD pixels look weak when driven with a too-low 5V rail voltage.

Basic knowledge of LCD keypad shield

The LCD keypad shield can connect directly to the Arduino Diecimila Duemilanove, UNO, MEGA1280,and MEGA2560 board. The LCD panel displays characters in white with a blue backlit and can display up to two lines of 16 characters.


The features of sainsmart LCD keypad shield:

This is a 16x2 LCD Keypad shield which can fit for Arduino Diecimila Duemilanove, UNO, MEGA1280,and MEGA2560 board.

Blue Backlight with white words, adjustable backlighting.

5V operating voltage

5 button keypad – up, down, left, right, and select which leaves the other analog inputs free for you to use in your projects.The buttons are arranged in a handy pattern and referred to as UP, DOWN, LEFT, RIGHT, and SELECT, but of course it's totally up to your sketch to decide what to do when any particular button is pressed.

It can work perfectly in 4-bit mode with the "LiquidCrystal" library included with the Arduino IDE, which allows you to control the LCD with a total of just 6 digital I/O lines. We've deliberately picked D4-D9 so that it doesn't interfere with pins required by other popular products such as the Ethernet Shield and EtherTen, so you can stack this on top of other shields to give you a local display.

An introduction of LCD Keypad Shield

The 16x2 sainsmart LCD Keypad Shield is easily to use generally because it is really entirely compatible using the Arduino "LiquidCrystal" library. You could potentially initialise the Liquid crystal display and exhibit messages on it with just a couple lines of code.However, it will add you the difficulty to do the projects.For example, displaying menu items and picking them to use the buttons.

What the power environment does the LCD Keypad Shield require?
The Lcd & Keypad Shield needs a good 5V electric power supply to ensure the backlight totally illuminates and the display contrast is high,if you power your Arduino from USB together with the Liquid crystal display Protect attached you may experience a voltage drop over the USB cable.

If you have trouble with dispiay contrast or backlight brightness, try attaching a power supply of around 7 to 9Vdc to the 2.1mm DC jack on the Arduino. A typical symptom in an undervoltage situation is that one line of the LCD will present pale rectangles in place of the characters, and the other line will clearly show nothing at all. The Arduino may even continue running normally since it is very happy at just 4V or so, but the LCD Keypad Shield won't function.
What the Library does the LCD Keypad Shield need?
All the hard work of interfacing with all the Liquid crystal display Shield is handled by the LiquidCrystal library, which is included as part of the official Arduino distribution. You can check whether you have it installed by starting up the IDE and looking under Files -> Examples -> LiquidCrystal. If it exists, you can do.