lcd displays random characters in stock

When I start my code, it displays as expected the initial screen on the LCD (as defined in setup() function) and then the temperature. But suddenly the LCD displays random characters, see attached, and somehow never stop displaying random characters until i restart the board.

So I am ultimately trying to build a fun security system using a 4x4 number pad, arduino, and a solenoid. While trying to get the number pad and LCD to work together, I keep running into issues for reasons unknown to me. The code below is what I have so far:

My LCD is showing random characters, see the picture below (the last character blinks, some characters change and over time there are slowly more and more characters). I"m starting to wonder if the LCD I chose has a driver compatible with the LiquidCrystal library, what do you think? If so what can I do to avoid buying another one?

In present scenario, we are giving supply to the LCD display with the help of 10 pin connector with 2 pins of 10 pin connector not connected and we attach power supply to the 2 wires left open.

Many of these LCD controllers differ slightly from the HD44780 controller in things like the initialization sequence, minimum delay between commands and maybe other ways I don"t know of.

try putting a 1n4148 diode between the 5V supply and the 5V of the LCD, so the LCD will get around 4.5V, that is enough for the LCD, and lowers its logical input levels enough so that it sees 3V3 logic highs as "1" reliably. The garbled letters, and blocks are due to the LCD sometimes seeing a "1" as a zero and that corrupts all communication between the PI and the LCD.

Its a well know problem when trying to drive an LCD with 3V3 levels, it actually needs minimally 3.5V when its powered with 5V (70 % of VCC = 0.7 x 5.0 = 3.5).

In the photos above the Pi is a Model B Rev 2 so should work fine with my tutorial. Random characters is usually a sign it has not been initialized correctly. Again this could be caused by intermittent connections.

I was having the same problem as the OP on my current build with an I2C back-packed LCD getting corrupted. I"d tried all kinds of things to fix the problems - changing the delays, trying different libraries, and pulling out hair with no joy in fixing it.

For anyone else with this problem, you may have what I have if you"re doing event-driven code e.g. from from a switch or rotary encoder. I was getting events triggered while the python code was trying to communicate with the LCD screen - which themselves tried to write to the LCD.

I also had the same problem with scrambled characters on my display. I found that there was a short between the data lines on the expander board where it is soldered to the display board. Once I cleaned up the messy solder, the display worked perfectly.

I"m working on a project whose objective is to control two ac loads (one ac fan, controlled by phase angle control and one ac motor controlled by a 5V relay) and output to an LCD the room temperature and the % of fan speed.

First, I put the lcd.clear() function in my code to "rebuild" the info from time to time but it doesen"t work 100% and it"s not a "clean" solution for the pourpose.

Previous examples connect the white LED backlight to power. The following example is specifically for those using an LCD with a RGB LED backlight. The only difference between the connection is the LED"s backlight on pins 15-18.

I started with the special characters, the Arduino Liquid Crystal library script "CustomCharacters". It is funny to see a moving character but this single character (5 by 8 pixels) remains so small. Making more of this jumping figures? But you have only 8 special characters to play with.

you can change the 8 special characters on the fly inside a script. Redefining the character makes all the positions with this character change at the same time, this creates wave like effects over the screen.

With the buffer you can make more effects than just the shifting (scrolling) left or right. In fact because you have the text inside an array you can choose which row to put on which line (scrolling up and down) or "random".

Making letters from bigger blocks of pixels creates a word the size of the screen. Alternating this with "normal" texts makes the LCD much more interesting.

By first calculating a shape, then rounding off and putting a character on that spot, you can create crude "bigger" shapes. It "just" works on this lcd with a letter resolution of 4 by 16: a sort of ellipse as a frame around a text for example.

Using a sequence (horizontal or vertical) of special characters and using the sequence (say 4) as a continuous array, you can "drop" a simple small shape, square of circle, continuously.

These are some ideas that are still possible with this simple LCD. Of course you can go on to the graphical screens where all the pixels can be used and the lines between the character spots doesn"t exist. But sometimes it is fun to explore what you can still do in more restricted situations...

lcd.print (char(i));You see that the special characters are two times displayed (in the first 16 memory slots)...I am still wondering if there are ways to get more out of this....

By making a block of say 2 x 4 special characters (this one gives 16 x 20 pixels), you can make a bigger "drawing". You have to brake down the drawing to fit in the different single special characters and this can be tedious.

I prepare this "image" in Photoshop using an image of 16 x 20 pixels. Either you can recode this to 8 special characters by hand or use a Processing sketch for this which scans an image and has as output the bytes in the format of the arrays. You can copy paste this code into the Arduino code directly.

To have a nice transition effect the content of the buffer is transferred to the screen in a random way, creating a bit of curiosity for the public. The message is revealed, rather than thrown on the screen.

(Suggestion for exploring: can we use the " " or space for the all white? This would save us defining a special character. How can we call a normal character like a special character? Answer: lcd.print(char(32)); )

Further building blocks are necessary because we have only 4 lines on the LCD. So a "H" or an "S" need a special "half" building block, upper and lower.

By using a sequence of 4 special characters and changing the content of the characters within the code in a continous way, yu can make some small drawing (snow flake) fall down:

Important is the Liquid Crystal Library I used, because this library, as the Arduino software environment will be updated. The library I used (with the issue of lcd.createChar(0, ) ) is included in the GITHUB repository.

LCD screens come in various sizes. Colors can be green, blue, black. Some have backlights, which can be used in some unexpected way (or just by night).

With these displays you have full control over the pixels. It is slower than the LCD"s. There are two colored displays and RGB displays, of course some even with touch.

With this resolution and colors, the magic of the LCD seems primitive but in fact, you are entering another domain of challenges, other laws of design.

The LCD screen is vital for operating the printer. Should you encounter any kind of trouble, such as a dead screen, corrupted text, or other issues, please refer to the guide below.

First of all, unscrew the LCD screen from the printer frame, remove both M3x10 screw holding it the LCD board in the plastic casing, and remove it from the casing. See if the problem still appears when the LCD is not pressed by the casing.

Firmware updates are necessary to keep your printer up to date. However, the installation of incorrect firmware can lead to letter corruption on the LCD screen. There"s an easy fix, though:

There is a small chance the printer"s LCD screen can glitch out by electrostatic discharge when inserting the SD card. Try to turn the printer off and on again.

This problem usually appears only on user-assembled printers. If your printer"s LCD screen remains blank or displays corrupted symbols after you turn on the printer, there is a chance it is caused by incorrect wiring. Follow these steps to fix the issue.

If you suspect that the LCD ribbon cables connectors are not firmly seated in the slots, disconnect the LCD ribbon cables and check the slots for any bent pins. If there are bent pins, you can use tweezers to fix them. However, be very careful not to break the pin(s) completely.

In this project, a digital dice will be designed. The objective of this project is to teach that how custom characters can be displayed on an LCD. In Arduino projects using 16X2 LCD for display, the characters can be directly printed on one of the two rows using print() function of the LCD library of Arduino. However, sometimes displaying custom characters on the LCD is the demand of the project. The same feature has been illustrated in this project by designing a digital dice.

A digital dice is a digital version of the regular dice. Any dice has six faces on which numbers from 1 to 6 are printed. On throwing a dice, one of the face and so one of the numbers between 0 and 7 appears on the upright face. It can be any random number between 0 and 7. The digital dice will also display a random number between 0 and 7 on every trial. When the project will be powered on, the LCD display will show a custom built “0” character. The trial will be simulated by pressing a switch on which a random number between 0 and 7 will be displayed on the 16X2 LCD. For the next trial, the LCD could be reset to display custom built “0” character on pressing another switch. Whenever custom character “6” will be randomly generated on LCD, a buzzer will start sounding to indicate that the user has got an additional trial.

The project is built on Arduino UNO and has a 16X2 LCD, a buzzer and a 2-switch keypad interfaced to it. The project code has been written Arduino IDE and burnt to the Arduino board through USB using AVR Dude.

In the project, LCD display is controlled by the Arduino UNO. The Arduino board runs the project code to generate a random number and display it as a custom character on the LCD display. The circuit has the following sections- :

16X2 LCD – The 16X2 LCD display is connected to the Arduino board by connecting its data pins to pins 3 to 6 of the Arduino board. The RS and E pins of the LCD are connected to pins 13 and 12 of the Arduino UNO respectively. The RW pin of the LCD is grounded.

The standard open-source library for interfacing LCD with Arduino UNO is used in the project. The library works as expected and needs no changes or modifications.

The project is based on generating a random number between 0 and 7 and displaying the digit as a custom character on 16X2 LCD. The custom characters will be displayed using four character blocks of the LCD of which two character blocks will be on top row and other two character blocks will be in the bottom row adjacent to the blocks in top row. Each character block on 16X2 LCD is 5X8 pixels. The individual pixels of the character block can be switched ON or OFF by passing HIGH or LOW logic respective to those pixels to the LCD’s inbuilt controller. Any custom character can be displayed on a character block by switching individual pixels ON or OFF together. In this project four character blocks will be passed custom characters to form a single large-size character. The character blocks used for displaying a large custom character on LCD will be Column 0 Row 0, Column 1 Row 0, Column 0 Row 1 and Column 1 Row 1.

When the project is powered on, it displays custom built zero “0” on the LCD. When trial switch is pressed, a random number between 0 and 7 is generated by the program code. Corresponding to the random number generated, predefined pixel maps are assigned to the four character blocks for displaying the respective large size custom character on LCD. If that number turns out to be “6”, the buzzer is started blowing to indicate that user gets an additional trial. The user can reset the LCD display to show large size zero again by pressing the Reset button.

The project will utilize standard open-source library of Arduino for LCD interfacing. So include LCD.h and define an object of LCD class. A constant for delay of 300 milliseconds is defined and variables to represent buzzer, dice button and reset button are defined and assigned to Arduino pins. A global variable to represent random number is declared.

A setup() function is called where the baud rate for serial transmission is set 9600 bits per second. The LCD is initialized using LCD.begin() function. The pinMode() function is used to set buzzer pin as output and button pins as digital input. Then, some initial messages are flashed on LCD screen.

A loop() function is called in which first the default character 0 is displayed on the LCD. The pressing of buttons is detected by detecting LOW logic at the pins. If Dice button is pressed, a random number between 0 and 7 is generated using random() function and assigned to “num” variable. If reset button is pressed, LCD display is cleared and “num” variable is assigned value 0. If the random number is 6 then a HIGH and LOW logic is passed to the buzzer pin for a delay of 100 milliseconds.

The value of “num” variable is checked through If-else statements and for value from 0 to 6, respective custom characters are created by assigning pixel map to character blocks using LCD.CreateChar() function. The parts of the large custom character are printed to the respective blocks by placing cursor at the respective character block and printing the character using lcd.write() function.

In the previous chapter, we have discussed how a character LCD is interfaced with a PIC microcontroller in 8-bit mode, where we used predefined characters stored in the LCD to display our data. In this article, we will learn more about the LCD and how we can create and use custom characters.

DDRAM or “Data Display Random Access Memory” is the working data buffer of the display. Each character on the display has a corresponding DDRAM location and the byte loaded in DDRAM controls which character is displayed.

CGROM or “Character Generation Read Only Memory” holds all the standard patterns for the 5 x 7 dot matrix characters. For instance, if you want to display character “A”, you would send ASCII code 65 (decimal) to the DDRAM. The display controller looks up the pattern of dots to display for this code in the CGROM and lights up the ones appropriate for “A”. The CGROM contents depend on the particular character set and model of display, US, Chinese etc. and cannot be changed.

CGRAM or “Character Generation Random Access Memory” allows the user to define special supplementary non-standard character types that are not in the CGROM. You can load your own dot pattern shapes and call these up for display.

For making custom patterns we need to write values to the CGRAM area defining which pixel to glow. These values are to be written in the CGRAM address starting from 0x40. CGRAM has a total of 64 Bytes. For LCD using 8×5 dots for each character, you can define a total of 8 user defined patterns (1 Byte for each row and 8 rows for each pattern).

Custom characters are assigned fixed display codes from 0 to 7 for pattern stored in the location pointed by CGRAM address 0x40, 0x48, 0x56… and so on. So, if the user wants to display second pattern (pattern stored at CGRAM address 0x48), simply call the data function with value 1 as an argument at a desired location in the LCD.

To display the sequence in the LCD, we need to specify the position on LCD and which pattern to display at the position. Provide adequate delay in between frames to observe the sequence distinctly.

4. If the customer is having difficulty reading the information displayed on the LCD or its too light, try changing the contrast setting. Adjusting the contrast will give the LCD a sharper and more vivid appearance.