gpiozero lcd display in stock
In this tutorial we"ll take you through how to connect a 16x2 LCD display up to your Raspberry Pi using GPIO pins. Being able to display a message on the LCD is not only very cool but can be pretty useful too, for example in this tutorial we"ll cover how to get your LCD display to display the IP address of your raspberry Pi.
For this exercise we are going to control the LCD display using 4-bit mode. Whilst is is possible to connect to it in other ways using I2C or the UART this is the most direct method. In order to control the display in this way will we need to use 6 pins on the GPIO port, 4 data pins and 2 control pins.
Register Select – This toggles the Lcd display between two modes, Command mode (high) and Data mode (low). Command mode gives a Instruction to the LCD. Example – “Clear the display” , “Move cursor to home” etc and Data tells the LCD to display characters.
In order for the LCD to work we will wire the circuit up in a fashion similar to the diagram above, but hold off connecting everything together for now! The list below tells you exactly what the pins on the LCD connect to:
Begin assembling the circuit by inserting the Adafruit cobbler into the breadboard. Remember to straddle the cobbler over the centre of the breadboard so that no two pin is in the same row. Next insert the LCD display into the breadboard. Connect the 5V and GND pins from the cobbler to the top of breadboard and also connect Pins 1, 2, 15 on the LCD and 16 to their respective power rails. Your circuit should look similar to the picture below:
Connect the GPIO ribbon cable from the cobbler to the Pi, if everything is working correctly the back light on the LCD should turn on like on the picture above. If it doesn"t work check everything is wired up correctly
Next wire up the potentiometer. The middle pin of the potentiometer is connected to Pin 3 on the LCD display and the other two pins are connected to ground and 5V (it doesn"t matter which way round). Check the potentiometer is working by twisting the nob until you see boxes appear in the first line of the display like in the picture below:
To get the Python code to run the LCD display we are going to "grab" it from adafruit using GitHub. Make sure your Rasp berry Pi is connected to internet and we"ll use the git command to clone the python code. Run the following commands in the terminal to download the files.
Now we can test the display is working and it is wired up correctly. One of the files we downloaded Adafruit_CharLCD.py contains python class for LCD display control. It also contains a small piece of code so when the program is run it will display a message on the LCD.
If you are using Version 2 of the Raspberry pi you will need to edit the program slightly since pin #21 has now been changed to pin #27. Open the file Adafruit_CharLCD.py with Python or use nano Adafruit_CharLCD.py command to edit the program within the terminal. Go to line 57 of the code and replace:
Feel free to dive into the code of the program and change what"s displayed on the LCD. To do so open the program to edit like before and scroll to the last line of the code:
Simply change what is typed in the brackets after lcd.message() to display the text you want. The command is used to wrap the text onto a new line. A neater way of doing this is to change the last part of the program to look like the following:
This way when you run the program you will be prompted by "type your message here" to enter a message via your keyboard, which will then be displayed on the LCD. This was done by defining a new variable "message" that is equal to the command raw_input(), which allows the user to manually enter text. The part within the brackets of the raw_input() command is simply printed on the computer screen to prompt you what to write.
Getting the LCD display to display some text of your choosing is cool but not that useful. Running the program Adafruit_CharLCD_IPclock_example.py will display the date/time and the IP address of the Pi on the LCD. The program calls upon the methods from the previous program Adafruit_CharLCD.py. Feel free to open the program to look at the coding. To do so open the program in python or use the command sudo nano Adafruit_CharLCD_IPclock_example.pyin the terminal.
You could create a simple python script that runs on startup with Cron. That script would display whatever you want for a small amount of time and then end. This would effectively tell you when your Pi"s done with booting or if it still is.
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Raspberry Pi 16×2 LCD I2C Interfacing and Python Programming– I have been using 16×2 LCD for quite a long time in different Arduino and IoT related projects. You know we have two types of the 16×2 LCD, the normal one used more wires and the other one is based on the I2C interface which needs only two wires.
If you have the plain version of this display then this tutorial is not for you. The plain version is not practical anyway it would use a lot of GPIO Pins and it has a complicated programming requirement.
With this version you need only four pins and the programming model is very simple. Other than the display you will need some wires. This is what I will be using.
The backpack module uses the I-squred-C (or I2C) protocol to communicate with the Raspberry Pi, which uses only two wires: SDA and SCL (data and clock). Please note that the display is a 5 volt device, and it is powered by 5 volts, but due to design of the I2C protocol, and the fact that the Raspberry Pi is the controlling device, it is safe to connect such display to the Raspberry Pi directly.
I suggest using wires of different colors to connect the LCD display. This minimizes the risk of damage due to incorrect connections. For example, I’m using
I use the cobbler connector with a breadboard, but the display can be connected to the GPIO headers directly, you’ll just need to use different wires. 5 volts and ground connections are close to each other here, while the SDA and SCL line are connected on the opposite side.
Before you start using the I2C 16×2 LCD display with Python, you need to make sure that the I2C protocol is enabled on your Raspberry Pi. You can use the sudo raspi-config utility to take care of that. This program is navigated using keyboard arrows, tab and the Enter key. Look for I2C in the interfacing options and enable it. Enabling I2C requires a reboot.
And you can also adjust the contrast using a small Phillips screwdriver. Set it somewhere in the middle. Be careful not to short anything with the screwdriver while you make the adjustment. Looks like my display is ready to go.
The 27 hexadecimal addresses happen to be the most common, but your display’s address may be different. For example, it could be 3f. This will depend on the chip version of the backpack module. As long as the i2cdetect command shows the display is connected, you are good to go.
The easiest way to program this 16×2 I2C LCD display in Python is by using a dedicated library. There are many to choose from. I like things simple, so the library I recommend is rpi_lcd.
This library has the default 27 address hard-coded. If your display has a different address you will need to change it. You need to find the library on your system and the following command should do that for you.
I use the clear function at the end of the program, otherwise the message will stay on the display after the program ends. The two numbers (1 and 2) at the end of the text function indicate which line of the display to use.
This is an opportunity to adjust the contrast, especially if the display does not show anything, if you don’t see the “Hello, Raspberry Pi!” message. The adjustment only affects the letters, not the backlight. The backlight in this model is not adjustable, it’s always on, but you can turn it off by removing the jumper on the backpack.
It is using RGB666 so GPIO22, GPIO23, GPIO24, GPIO25, GPIO26, GPIO27 should be unused. The schematic for the RGB LCD HAT confirms that they"re not connected. You should be able to reuse one of those GPIOs but you"ll need to solder wires to the top of the header on the HAT as the unused GPIOs aren"t broken out to a pin or pad.
Yes but you"ll need to test it. Extending the LCD interface pins isn"t a great idea but it is probably okay as the Adafruit DPI TFT Kippah setup has a much longer ribbon cable anyway. Another potential issue is that it isn"t very compact as over half the RGB LCD HAT will hang over the edge.
Yes but you"ll need to test it. Extending the LCD interface pins isn"t a great idea but it is probably okay as the Adafruit DPI TFT Kippah setup has a much longer ribbon cable anyway. Another potential issue is that it isn"t very compact as over half the RGB LCD HAT will hang over the edge.
Once you’ve played with LEDs, switches and stepper motors the next natural step is 16×2 alphanumeric LCD modules. These modules are cheap (less than $10) and easy to interface to the Raspberry Pi. They have 16 connections but you only need to use 6 GPIO pins on your Pi.
Most of the 16×2 modules available are compatible with the Hitachi HD44780 LCD controller. This allows you to buy almost any device and be sure it is going to work in much the same way as any other. There are loads to choose from on eBay with different coloured backlights. The one I purchased had a blue backlight.
You can control a HD44780 style display using any programming environment you like but my weapon of choice is Python. I use the RPi.GPIO library to provide access to the GPIO.
This script can be downloaded using this link or directly to your Pi using the following command :wget https://bitbucket.org/MattHawkinsUK/rpispy-misc/raw/master/python/lcd_16x2.py
Additional Notes : RS is low when sending a command to the LCD and high when sending a character. RW is always low to ensure we only ever input data into the module. 8 bit bytes are sent 4 bits at a time. Top 4 bits first and the last 4 bits second. Delays are added between certain steps to ensure the module can react to the signal before it changes.
The code above was inspired by code submitted by ‘texy’ on the RaspberryPi.org forum. I changed the way the bytes are broken down to bits as this significantly increased the response time of the display.
Note:In order to control the contrast you can adjust the voltage presented to Pin 3. This must be between 0 and 5V. We used a resistor between pin 3 of LCD to GND of PI.
In the above tutorial we saw how to display the custom message on 16 X 2 LCD using raspberry pi and python.Now we shall move on how to display the current weather info on LCD:First we will need to download the python weather api.Download thepywapilibrary using the following command on your pi.wget https://launchpad.net/python-weather-api/trunk/0.3.8/+download/pywapi-0.3.8.tar.gz