CharDisplay

Raspberry Pi package for controlling 16x2 character display (1602 LCD) on HD44780U module written in Julia.

Installation

Julia must be installed on Raspberry Pi. I have tested on v1.1.0 which can be installed with:

sudo apt update
sudo apt install julia

The package can be installed from Julia environment with:

] add https://github.com/metelkin/CharDisplay.jl.git

Usage

# setting connected pins
d = DisplayP4(
    2, # RS
    3, # RW
    4, # E
    5, # D7
    6, # D6
    7, # D5
    8  # D4
)

write(d, "Julia +")
set_cursor(d, 0, 1) # move cursor to the second line
write(d, "Raspberry Pi")

Circuits

A. Connection for 4 bit mode

Display pins can be connected to any RaspberryPi GPIOs. For example this scheme is based on the following connections:

VSS => GND (chip ground)
VDD => +5V (chip power)
V0 => central terminal of the potentiometer to get 0..+5V
RS => GPIO2
RW => GPIO3
E => GPIO4
D7-D4 => GPIO5-GPIO8
A, R (light power) can be connected to 3.3V or 5V bus

scheme-a

B. Connection for 8 bit mode

Display pins can be connected to any RaspberryPi GPIOs. For example this scheme is based on the following connections:

VSS => GND (chip ground)
VDD => +5V (chip power)
V0 => central terminal of the potentiometer
RS => GPIO2
RW => GPIO3
E => GPIO4
D7-D0 => GPIO5-GPIO12
A, R (light power) can be connected to 3.3V or 5V bus

scheme-a

Known issues and limitations

Currently only parallel 8bit/4bit mode (without display driver) is supported.
The maximal rate (333 Byte/s) is limited by too long pauses between switching pins. The package uses sleep(time) function where time cannot be less than 1e-3 (second). The theoretical rate can be 25000 Byte/s and it needs another approach without sleep function.
The package works only in writing mode. Reading mode and checking BF (busy flag) signal is not supported.

For more information read datasheet to the module
https://www.mbtechworks.com/projects/drive-an-lcd-16x2-display-with-raspberry-pi.html