Character LCDs with I2C Serial Bus Interface

The I2C Serial Bus Interface

The three most popular interfaces for LCDs are: Parallel, SPI and I2C serial bus. The most popular LCD technology that Focus carries in stock is the character LCD. These displays, aka as alphanumeric displays, now have the ability to support an I2C Serial Bus in addition to the older 8 bit and 4 bit parallel interfaces.

The I2C serial bus has been popular with other types of liquid crystal displays such as Graphic LCD displaysTFT’s and custom segment LCD’s; but now there is an option to order a 16×2 I2C serial character display.

Why I2C

The I2C bus, has the advantage of requiring less pins than the more common 8-bit parallel option. This comes into play when the designer of the product does not have as many I/O (In/Outs) with their microprocessor or pic controller.

The I2C serial bus character display only requires 5 pins or 6 with a LED backlight. Whereas the 8-bit parallel interface requires 14 pins or 16 pins with a backlight including the following:

  • DB0 through DB7 (Data bits)
  • RS (Register Select signal)
  • R/W (Read/Write Select signal)
  • Enable (Enable signal)

Below is a diagram showing the operation of the I2C bus. This structure allows multiple accessories to be addressed by just on master chip (McU). The advantage is the ability to add more and more devices to the same controller without increasing your pin out.

All of FocusLCDs character LCDs are available with the standard 8-bit parallel interface and in most cases can ship to the customer the same day.

At this time, FocusLCDs only carries a few standard I2C character LCDs in stock.

Non-standard character LCDs

It is possible to modify any standard 8-bit character LCD to an I2C or SPI interface. There is a one-time tooling fee and the lead time can range from five to seven weeks.

Contact Focus Display Solutions at 480-503-4295 for questions and support.