arduino lcd displays garbage in stock

I"m having the same problem. I have a shield with combined RTC and SD card. I"ve wired up the LCD (16 x 2) and it works perfectly when I use the simple sample code for the LCD. I"ve noticed that it also works fine when I integrate the code into my program which utilizes the RTC and SD card IF AND ONLY IF I write to the LCD before initializing the SD or RTC. Actually, I saw the comments about SPI conflicts etc, so I modified the pins for the LCD a few times and found that in the original configuration, I could write to the LCD successfully AFTER the RTC initialization, but not after the SD card. Then, after I switched the pins, and it ONLY works if I write to the LCD at the beginning of the Setup() function before both RTC and SD calls. I thought I understood the potential conflicts so I"ve wired the LCD to pins as follows:

This doesn"t seem to be using any pins that conflict, but maybe I"m missing something? I have an Uno and am also using pins 2-4 for an optical sensor so they are not avail. Thoughts on how to resolve the conflict? Oh, the problem I"m having is that any writes to the LCD are correct ahead of the RTC/SD initializations, but I get gibberish when I write after those calls.

Hi, i have and LCD 16x2 connected to my Leonardo. I works properly with all the examples son the connection is ok. But I add the LCD to another sketch and it"s just showing garbage, and i have no idea why. I just want to show "Writing:" in the first row, and the variable nombrearchivo in the second row. All of this works using serial, so my only problem is the LCD.

That"s a good idea. Unfortunately after look at it though I"m not sure that EM interference would be it. Since these lights are in use keeping my corals alive I do most of my testing at night during at time where the value should read 0. The second sketch I posted was one I used to test the 10v circuit being on full power (255) and the LCD doesn"t seem to care. So it can be at 255 and not have problems, it can be at 0 and not have problems as long as I only use analogWrite(ledPin, 0) and not map. I won"t rule it out thought. The drivers aren"t exactly close to my working area, but I can move them further. Also, the result of what"s on the screen sort of varies. In the sketches I posted I"m actually using two different methods of getting the time and temperature. I have adapted the methods I use in the second sketch to the first sketch. In that case I do just get garbage, but the screen doesn"t just turn off after a few seconds. The first sketch I posted the date I have printing to (0,0) starts to get some numbers added into it, maybe a weird character, but it usually will drop out and the screen go blank after a few seconds. The sketch I"ll post below doesn"t go blank and has blocks going in spaces that I"m not printing to and the spaces I"m printing to has garbage scrolling through.

However, I do want to add that I don"t mind you advertising that product. I actually like that idea very much. I have a flexible keypad thing I just threw in the order with my LCD. I figured I"d get around to messing with it. I do need some kind of input at some point for a few things, like starting a feeding mode that turns off power heads in my tank so the fish can eat and priming for dosing pumps and such. Anyway, it would be nice to have some buttons built into the screen. I"ll definitely bookmark that and I may have recommend it to some people that are following my project locally. Would certainly be easier for setting them up. I also kinda like the idea of the black on green style since I guess you still read the screen with the backlight off. This is a minor thing though. I know a lot of the people I"ve showed my project here to really like the white on blue. Just skimming over the features you list though, and I really do like it. The buzzer would be perfect for alarms I eventually want to set. Yea, you could say I"m very interested now. Thanks for bringing that up.

Just a few lines to share my experience with I2C - 20X4 LCD display. Sometimes it works perfectly sometimes garbage appears all over the display. I checked my code and couldn"t find anything wrong.

I started to think it was an hardware problem. I touched the I2C module and garbage appeared immediatly. I thought it was a bad solder so I heated each I2C pins connected to the LCD display. Problems disappeared for sometime but garbage was back few days later. I decided to order à new I2C board to interface the LCD display which is much less expensive than changing the 20X4 display.

So if you experience occasional display problem, look at you I2C module, touch it, twist it, try to lift it, etc... if garbage appears ... you have a good indication of where your problem could be.

I"m just dipping my toe into the whole Arduino stuff. I"m not a programmer by trade, but have poked around in it here and there. I"m not great, but I comprehend the basics.

I got a kit that included a bunch of widgets, inputs and outputs. I"ve got a 16x2 LCD screen hooked up and working using code I"ve found in a couple of tutorials (forgive me, I don"t even know which one I"m using at this point).

So, I tried the next step, of combining the two. I"ve got the rotary encoder position counter working, and outputting to the LCD screen. When I rotate right, the number goes up, and when I rotate left, the number goes down.

I"ve looked around and have seen some stuff about rotary encoders skipping numbers (which also happens), but I haven"t seen much about it outputting garbage. I should note that the serial monitor also shows garbage data sometimes, but not the same stuff the LCD is showing.

The lcd.clear function is slow and can lead to screen flicker especially if done every time through loop(). Overwrite old data with spaces, reset the cursor position and print the new data and only update the screen when the data changes will help prevent flicker.

We come across Liquid Crystal Display (LCD) displays everywhere around us. Computers, calculators, television sets, mobile phones, digital watches use some kind of display to display the time.

An LCD screen is an electronic display module that uses liquid crystal to produce a visible image. The 16×2 LCD display is a very basic module commonly used in DIYs and circuits. The 16×2 translates o a display 16 characters per line in 2 such lines. In this LCD each character is displayed in a 5×7 pixel matrix.

Contrast adjustment; the best way is to use a variable resistor such as a potentiometer. The output of the potentiometer is connected to this pin. Rotate the potentiometer knob forward and backwards to adjust the LCD contrast.

A 16X2 LCD has two registers, namely, command and data. The register select is used to switch from one register to other. RS=0 for command register, whereas RS=1 for data register.

Command Register: The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task. Examples like:

Data Register: The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. When we send data to LCD it goes to the data register and is processed there. When RS=1, data register is selected.

Generating custom characters on LCD is not very hard. It requires the knowledge about custom generated random access memory (CG-RAM) of LCD and the LCD chip controller. Most LCDs contain Hitachi HD4478 controller.

CG-RAM address starts from 0x40 (Hexadecimal) or 64 in decimal. We can generate custom characters at these addresses. Once we generate our characters at these addresses, we can print them by just sending commands to the LCD. Character addresses and printing commands are below.

LCD modules form a very important in many Arduino based embedded system designs to improve the user interface of the system. Interfacing with Arduino gives the programmer more freedom to customise the code easily. Any cost effective Arduino board, a 16X2 character LCD display, jumper wires and a breadboard are sufficient enough to build the circuit. The interfacing of Arduino to LCD display below.

The combination of an LCD and Arduino yields several projects, the most simple one being LCD to display the LED brightness. All we need for this circuit is an LCD, Arduino, breadboard, a resistor, potentiometer, LED and some jumper cables. The circuit connections are below.

In the previous tutorial, we discussed multiplexingseven-segment displays(SSDs). Continuing with the display devices, in this tutorial, we will cover how to interface character LCD when using Arduino. Character LCDs are the most common display devices used in embedded systems. These low-cost LCDs are widely used in industrial and consumer applications.

For instance,LEDsare used as indicators of mutually exclusive conditions. The SSDs are used to display numeric information. The Liquid Crystal Displays (LCDs), TFTs, and OLED displays are used to present the more complicated information in embedded applications. Often, this complication arises due to the text or graphical nature of the information or the interface.

The character LCDs are used where the information or interface is of a textual nature. The graphical LCDs are used where the information or interface is of a graphical nature. The graphical LCDs that are used to design machine-human interfaces may also have touchscreens.

Character LCDsCharacter LCDs are useful in showing textual information or to provide a text-based, machine-human interface. It’s even possible to display some minimal graphics on these LCDs. These are low-cost LCD displays that fit in a wide range of embedded applications.

Generally, character LCDs do not have touchscreens. And unlike graphical LCDs, these LCDs do not have continuous pixels. Instead, the pixels on character LCDs are arranged as a group of pixels or dot-matrix of pixels of fixed dimensions.

The character LCDs are classified by their size, which is expressed as the number of characters that can be displayed. The number of possible characters that can display at a time on the LCD is indicated as the number of columns of characters and the number of rows of characters.

The common size of character LCDs is 8×1, 8×2, 10×2, 16×1, 16×2, 16×4, 20×2, 20×4, 24×2, 30×2, 32×2, 40×2, etc. For example, a 16×2 character LCD can display 32 characters at a time in 16 columns and 2 rows. Generally, characters are displayed as a matrix of black dots while the backlight of LCD may be a monochromatic color like blue, white, amber, or yellow-green.

The character LCDs may use any one of these types. The TN types are low-cost but have a narrow viewing angle and low contrast. The FSTN offers the best contrast and widest viewing angle, but they are more costly. Even character LCDs that use the FSTN display are still cheaper in comparison to graphical LCDs, TFTs, and OLEDs.

Most of the character LCDs use LED backlight and the backlight color can be white, blue, amber, or yellow-green. The other types of a backlight in character LCDs include EL, CCFL, internal power, external power, and 3.3 and 5V backlights. EL and LED backlights are the most common. The LCD may have a reflective, trans-reflective, or transmissive rear polarizer.

The quality of display depends on the LCD type, the backlight, and the nature of a rear polarizer used in the LCD panel. When selecting an LCD panel for an embedded application, it’s important to decide on the quality of the LCD display, according to the requirements. This includes per the application, class of the device, nature of use (such as indoor or outdoor), target users of the device, intended user-experience, operating conditions (such as temperature and operating voltage), and cost limitations.

For example, a character LCD that has to be used for the machine-human interface must have better contrast, a wide viewing angle, and a good backlight.

Even on a character LCD, a large number of pixels have to be controlled to display the text. A 16×2 character LCD in which each character is 5×8 pixels means that a total of 1280 pixels (16×2 characters x 5×8 Pixels) have to be controlled. This requires interfacing the pixels across 16 rows (2 rows of characters x 8 rows in each character) and 80 columns (16 columns of characters x 5 columns in each character) of connections.

This is when pixels are black dots and merely require switching either ON or OFF by the controller to display text characters. On a typical microcontroller, there are not these many I/O pins that can be dedicated to controlling the pixels of an LCD panel. That is why LCD modules have integrated controllers that control the pixels of the LCD. The integrated controller can interface with a microcontroller or a processor via an 8-bit/4-bit parallel port or a serial interface (like I2C). The integrated controller receives data and commands from the microcontroller/processor to display text on the LCD panel via a 4-bit/8-bit parallel or serial interface.

In fact, the LCD module is a complete embedded system comprising of an LCD panel, LCD driver, LCD controller, LED Backlight, internal flags, Address Counter, Display Data RAM (DDRAM), Character Generator ROM (CGROM), Character Generator RAM (CGRAM), Data Register (DR), Instruction Register (IR), and Cursor Control Circuit.

1. LCD Panel. The character LCDs have the dot-matrix LCD panel. The text characters are displayed on the panel according to the commands and data received by the integrated controller.

2. System Interface. This module has a 4-bit and an 8-bit interface to connect with microcontrollers/processors. Some LCD modules also have a built-in serial interface (I2C) for communication with a controller. The selection of interface (4-bit or 8-bit) is determined by the DL bit of the Instruction Register (IR).

5. Character Generator ROM (CGROM). It’s an internal Read-Only Memory (ROM) on the LCD module where the patterns for the standard characters are stored. For example, a 16×2 LCD module, CGROM has 5×8 dots, 204 character patterns, and 5×10 dots of 32 characters pattern that are stored. So, the patterns for the 204 characters are permanently stored in the CGROM.

6. Character Generator RAM (CGRAM). The user-defined characters can also be displayed on a character LCD. The patterns for custom characters are stored in CGRAM. On the 16×2 LCD, 5 characters of the 5×8 pixels can be defined by a user program. The user needs to write the font data (which is the character pattern defining what pixels/dots must ON and which must OFF to properly display the character) to generate these characters.

7. Display Data RAM (DDRAM). The data sent to the LCD module by the microcontroller remains stored in DDRAM. In 16×2 character LCD, DDRAM can store a maximum of 80 8-bit characters where the maximum of 40 characters for each row can be stored.

9. Busy Flag (BF). The bit DB7 of the instruction register is a busy flag of the LCD module. When the LCD is performing some internal operations, this flag is set (HIGH). During this time, the instruction register does not accept any new instruction via the system interface from the microcontroller. New instructions can be written to the IR but only when the busy flag is clear (LOW).

11. LCD Driver. It controls the LCD panel and the display. In the 16×2 character LCD, the LCD driver circuit consists of 16 common signal drivers and 40 segment signal drivers.

12. Timing Generation Circuit. It generates the timing signals for the operation of internal circuits, such as the DDRAM, CGRAM, and CGROM. The timing signals for reading RAM (DDRAM/CGRAM) module are generated separately to display characters and timing signals for the internal operations of the integrated controller/processor of LCD. This is so that the display does not interfere with the internal operations of the integrated controller of the LCD module.

Interfacing character LCDsMost of the character LCDs have a 14-pin or 16-pin system interface for communication with a microcontroller/processor. The 16-pin system interface is the most common.

To interface the LCD module with a microcontroller or Arduino, the digital I/O pins of the microcontroller must be connected with the RS, RW, EN, and data pins DB0 to DB7.

In 4-bit mode, two pulses are required at the EN pin to write data/instruction to the LCD. At first, the higher nibble of data or the instruction is latched. Then, in the second pulse lower nibble of the data/instruction is transferred.

In an 8-bit mode, the entire 8-bit data/instruction is written to the LCD in a single pulse at the EN pin. So, the 4-bit mode saves the microcontroller pins but has a slight latency in comparison to the 8-bit mode of operation. The 8-bit mode suffers less from latency but engages 4 extra pins from the microcontroller.

It’s also possible to interface the LCD module with Arduino using a serial-to-parallel converter. Then, only two pins of Arduino are required to interface with the LCD module.

The ground pin of the LCD module (pin 1) must be connected to the ground while the VCC pin (pin 2) must be connected to the supply voltage. The 3.3 or 5V pin of Arduino can be used to supply voltage to the LCD module. The VEE pin must be connected to the variable terminal of a variable resistor, and the fixed terminals of the variable resistor must be connected to the VCC and ground.

How character LCD worksIt is possible to read/write data with the LCD module. To write data/instructions to the LCD module, the RW pin must be clear. Then, if the RS is set, an 8-bit data sent by the microcontroller stores in the data register (DR) of the LCD module. This 8-bit data sent by the microcontroller will store in the instruction register (IR) of the LCD module.

When data is sent to the LCD module (RW=0, RS=1, EN=1->0), it is written in the DDRAM and the Address Counter of the LCD is increased by one. The LCD controller compares the 8-bit data with the CGROM addresses and displays the appropriate character on the LCD at the associated DDRAM address. This serves as the instruction to show that the display has been received.

When the instruction is sent to the LCD module (RW=0, RS=0, EN=1->0), it is stored in the instruction register and according to the pre-defined instruction set of the LCD controller, the appropriate operation is executed on the display (to set display ON, set display OFF, set cursor ON, set cursor OFF, clear DDRAM, etc.).

Sometimes, the microcontroller may need to read data from the LCD. A microcontroller can read content from the instruction register, DDRAM, and CGRAM of the LCD. To read data from the LCD, the RW pin must be set. When the RW is set and the RS is clear, the microcontroller reads the content of Instruction Register (IR) — including the busy flag (DB7 of IR) and address counter (DB6 to DB0 of IR) — when applying a HIGH to LOW pulse at EN pin.

If the LCD module is interfaced to typical microcontrollers (8051, PIC, AVR, etc.), the RS, RW, EN, and the data bits need to be set individually to perform the read/write operations.

Arduino has a Liquid Crystal library (LiquidCrystal.h) available that makes programming LCD with Arduino extremely easy. This library can be imported by the following statement:

LiquidCrystal() methodThis method is used to create a Liquid Crystal object. The object must be created according to the circuit connections of the LCD module when using Arduino.

The object takes the pin numbers of the Arduino as arguments. The pin numbers where the RS, RW, EN, and the data pins (DB7-DB0 for 8-bit mode and DB7-DB4 for 4-bit mode) of the LCD are connected, has to be passed as arguments in the object definition.

This method is used to initialize the LCD module. The function takes the size of the LCD (expressed by number of columns and rows in the LCD) as the arguments.

This method positions the cursor at the given location on the LCD panel. It takes the column and row as the argument where the cursor has to be placed and a subsequent character has to be displayed.

This method is used to print text to the LCD. It takes a string argument, which has to be displayed at the current cursor position on the LCD. It can take base of the value passed as an optional argument — if only printing numbers.

How to check the LCDA common concern when interfacing the LCD module is to identify whether or not the LCD module is, indeed, working. When connecting the LCD with Arduino (or any other MCU), if only the lower line of the LCD brightens, then the LCD module is working.

Sometimes when you try to print on the LCD, nothing occurs, except the lower line of the LCD illuminating. In this case, the possible reasons can be one of the following:

2. The LCD module might have been interfaced in the reverse pin order (i.e. instead of pins 1 to 16, circuit connections might have been made from pins 16 to 1 of the LCD module).

4. The contrast of the LCD at the VEE pin might not have been adjusted properly. If the adjustment of contrast does not work, try connecting the VEE pin directly to the ground, so that the LCD module is adjusted to maximum contrast.

5. If after checking all the circuit connections, LCD panel still does not display text, check if the code uploaded to Arduino is correct or not. For example, it is possible that if the LCD display is not cleared after initialization, garbage values may display on the LCD instead of the intended text.

Components required1. Arduino UNO x12. 16×2 character LCD x13. 10K Pot x14. 330 Ohms Resistor or any low-value resistor x15. Breadboard x16. Male-to-Male Jumper Wires or Connecting Wires

Circuit connectionsThe LCD module used in this project is JHD162A. This is a 16×2 LCD module with 5×8 character dots. The LCD module has a 16-pin interface. The LCD is interfaced with Arduino in 4-bit mode.

Pin 1 (GND) and 16 (LED) of the LCD module are connected to ground while pin 2 (VCC) is connected to the VCC. The pin 15 (LED+) from the LCD module is, once again, connected to the VCC via a small-value resistor. The pin 3 (VEE) is connected to the variable terminal of a pot while the fixed terminals of the pot are connected to the ground and VCC.

The R/W pin is connected to the ground as Arduino will only write data to the LCD module. The RS, EN, DB4, DB5, DB6, and DB7 pins of the LCD are connected to pins 13, 11, 7, 6, 5, and 4 of Arduino UNO, respectively. The breadboard supplies the common ground. The 5V supplies the rail from one of the ground pins and 5V pin of the Arduino UNO, respectively.

The LCD module is connected with Arduino in a 4-bit mode. First, the LCD is initialized and the display is cleared to get rid of any garbage values in the DDRAM. The cursor is set to column 1 of the line 0, and the text, “EEWORLDONLINE” is printed on LCD.

Next, the cursor is moved to column 0 of line 1 and text, “EngineersGarage” is printed on the LCD. A delay of 750 milliseconds is given and the LCD is cleared again.

The cursor is moved to column 0 of the line 0 and the text, “EngineersGarage” is printed on the LCD. The cursor is then moved to column 1 of line 1 and text, “EEWORLDONLINE” is printed on the LCD.

Programming guideThe LiquidCrystal.h library is imported in the code. Then, an object defined by the variable “lcd” is defined for the LiquidCrystal class.

In the loop() function, the LCD display is cleared using the clear() method and he cursor is set at column 1 of line 0 by using the setCursor() method. The text “EEWORLDONLINE” is printed using the print() method on the “lcd” object. Similarly, the text “EngineersGarage” is printed at column 0 of line 1. A delay of 750 milliseconds is given by using the delay() function.

The body of the loop() function will keep repeating itself until Arduino is shutdown. Therefore, both texts keep displaying on the LCD module, alternating their position between line 0 and 1 of the panel.

We recently replaced our family of CFAO12864D3 graphic LCD displays with a new family of 128×64 low power backlit LCDs, but we have some of the Blue D3 displays left in stock. They’re great displays with bright backlights and we have an Arduino-shield style breakout board for them, so they’re great for hobby builders! A … Read more Arduino Shield LCD Giveaway!

This guide will walk through how to get started with one of our small full color OLED displays. Then, we’ll talk about a super quick and easy project to do with this display – a photo slideshow! The display we’ll be using is a 0.96″ full color OLED. We have two versions of this display, … Read more Tiny OLED Full Color Slideshow

Relevant Displays and Kits Do you need help getting started with your graphic LCD and CFA10110 adapter board? This getting started guide helps bring up any of the following displays or kits: Low Power Transflective Graphic LCD Module (CFAG12864T3-NFH-E1-1) Low Power Transflective LCD Dev Kit (CFAG12864T3-NFH-E1-2) 128×64 Backlit Transflective LCD with Breakout Board (CFAG12864T3-TFH-E1-1) Small … Read more Graphic LCD Adapter Board: CFA10110 Getting Started

DIY Transparent Display The transparent display we offer for sale (CFAL12856A0-0151) is an OLED (Organic Light Emitting Diode) display. OLED displays produce images by emitting light in the corresponding color. To produce black in a normal OLED, the pixels are simply turned off. With the transparent display, if the pixels are turned off, the display … Read more Transparent Display: How to Hack Together Your Own Transparent Display

This guide is for bringing up a compatible OLED display on a CFA10105 breakout board. Compatible OLEDs include: the transparent and these white and yellow displays.

Have you ever tried to bring up a display only to have it show you something like this? What are some common problems with LCDs showing garbage? If it is a new design or a prototype using a common HD44780 style LCD, then it is almost certainly wiring or code. Troubleshooting Wiring Problems: Ask someone … Read more Help! I have garbage showing on my 16×2 LCD