LCD display with SN74164 serial shift register interfaced to Arduino microcontroller.
LCD display with SN74164 serial shift register interfaced to Arduino microcontroller.

Interfacing Arduino SN74LS164 Serial Shift Register Driving LCD HD44780 Display

by Lewis Loflin

Here we will explore how to connect Arduino to a 2 or 4 line by 16 or 20 character LCD HD44780 based display. The electrical connections are shown above. I have avoided user supplied libraries because changes in the Arduino compiler means some of them don't work. The other point being how to write one's own code and get a better understanding of the electronics and how a micro-controller really operate. This will enable the student or hobbyist to connect other similar devices or learn how to connect new devices.

The code will allow one to display characters, strings, integers, and floats on the HD44780 LCD display. Some of the code was borrowed from the following projects minus the GPIO expander and the use of a 74HC164 code for Arduino.

YouTube video for this project: Using a SN74164 Serial Shift Register with a HD44780 LCD Display and Arduino

About the SN74164 Shift register and the LCD Display

Demo to shift byte into 74HC164 to operate LCD display.
8-Bit Serial-In - Parallel-Out Serial Shift Register

In the case of the HD44780 type display
Q1-Q7 of the 74164 connects to D0-D7 LCD.

The 74HC164 has three inputs:

Input A-B (pins 1, 2) is for data. they can be tied
together or the one not used tied to +Vcc

Clock pin 8 data is serially shifted in and
out of the 8-bit register during
the positive going transition of clock pulse.

Clear (pin 9) is independent of the clock
and accomplished by a low level at the
clear input. Can connect to Vcc.

As far as LSB first or MSB bit first is up to software
and electrical connections on the output.

LCD pin 6 (E), HIGH to LOW transition will clock
info into display. Select command or data with RS.
RS -> 0 is command, 1 is data. R/W goes to ground.

Complete code for this project: arduino_74164.txt

Download the complete code for this demo: arduino4a.txt.

Stepper Motors

Serial LCD Display and assorted Sensors

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If using this material on another site, please provide a link back to my site.