So I will use – LiquidCrystal_I2C lcd(0x27,16,2). The I2C address of my display is 0x27 and it has 16 columns and 2 rows. It requires three variables – the I2C address of the LCD and the dimension of the LCD (columns and rows of the display). In the second line, I create a LiquidCrystal_I2C variable. But before uploading this sketch you need to do some minor changes according to your display size and address. The below sketch will print some text on the display. To change the default address it has address selection pads – A0, A1, and A2. If you use multiple I2C devices on the same I2C bus, sometimes you need to change this default I2C address to avoid conflict with other I2C devices. Sometimes you need to change this default I2C address for a project where you use multiple I2C devices on the same I2C bus So that it does not conflict with other I2C devices. The PCF8574 chip from NXP Semiconductor uses 0x27 while the PCF8574A chip uses 0x3F. Each of these chips has its own I2C address. Some I2C LCD adapters come with PCF8574, while others use PCF8574A chips. The I2C LCD adapter also has a small trim pot to adjust the contrast of the display. You can remove the jumper to turn off the backlight LED or you can use a potentiometer in between these two pins to control the intensity of the backlight LED. These two pins are connected together by default. One pin supplies a 5v power and another pin is for the backlight LED. You can read more about it here: GitHub - duinoWitchery/hd44780: Extensible hd44780 LCD libraryThere are two header pins to control the backlight of the LCD display. It is available in the IDE library manager for quick and easy installation. It also includes a diagnostic sketch, I2CexpDiag, to verify that the LCD and library are properly working. It will auto locate the LCD and can auto configure the PCF8574 to LCD pin mappings and backlight control. In terms of libraries, I would recommend using my hd44780 library with the hd44780_I2Cexp i/o class. It will also make the signals more reliable and allow using both 3v and 5v i2c slaves since it creates a bus for each voltage. They are very inexpensive and will prevent any sort of damage to the DUE from pullups on 5V slaves. My recommendation would be use a level shifter. This can change and voltage may rise up to damaging levels. However, depending the pullups used on the 5v i2c slave and how many 5v slaves are connected to the bus, The DUE pullups will fight the 5v slave pullups to pull the i2c signals down to a lower level that is usually safe for the processor. Those pullups will prevent damage to the DUE processor in most cases when a single I2C slave is used as That circuitry is just on board pullups to 3.3v The DUE board doesn't really have a "I2C Voltage Translator" as labeled on the schematic. So in most cases when using these types of 5v devices, the i2c signals will not have pullups connected only to 3.3vĪs the 5v slaves are connecting the i2c signals to pullups going to 5v. What that means when using them "as supplied/shipped" and supplying them with 5v (which they need) they will have on board pullups going to 5v. Many if not most of the low cost devices like LCD backpacks and LCD modules have on board pullups that connect "if pull up resistors are connected to 3.3V as they should" Level shifters not being necessary is not a fact and a key part of that statement is the back end of it: In fact, level shifters are not necessary (but safer) if pull up resistors are connected to 3.3V as they should.
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