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Use the 74HC595 Shift Register with a Raspberry Pi

Project description

pi74HC595

Allows for easy use of the 74HC595 Shift Register with a Raspberry Pi

Pypi version Python version License Downloads

Install

$ pip install pi74HC595

Hardware

Raspberry Pi Pinout 74HC595 Pinout
Raspberry Pi Pinout 74HC595 Pinout

You will need to connect:

  • Vcc and MR to 5V

  • GND to Ground

  • Ds to any GPIO pin (DS pin during initialization)

  • STcp to any GPIO pin (ST pin during initialization)

  • SHcp to any GPIO pin (SH pin during initialization)

  • Q0 -> Q7 to anything you want to output to (not all have to be used)

  • Q7' to Ds on the next pi74HC595 if Daisy Chaining (multiple 74HC595s in series)

Initialize pi74HC595 class

gpio.setmode() can be either gpio.BOARD or gpio.BCM (pin numbering vs GPIO numbering).

from pi74HC595 import pi74HC595
import RPi.GPIO as gpio

gpio.setmode(gpio.BOARD)
shift_register = pi74HC595()

This package's default pins assumes gpio.BOARD as default

There are some default settings:

def __init__(
        DS: int = 11, # gpio.BOARD
        ST: int = 13,
        SH: int = 15,
        daisy_chain: int = 1,
    )

Pin Numbering

You will likely need to change the Raspberry Pi pins during initialization. Remember to check whether you used gpio.BOARD or gpio.BCM in your program.

shift_register = pi74HC595(7, 37, 22)

These can also be set after initialization with...

shift_register.set_ds(7) # Any GPIO pin on Raspberry Pi
shift_register.set_sh(37)
shift_register.set_st(22)

Daisy Chaining

If you are daisy chaining multiple 74HC595s then you can set daisy_chain to your number of 74HC595s during initialization.

shift_register = pi74HC595(7, 37, 22, 2)

shift_register = pi74HC595(daisy_chain = 13)

# etc

This can also be done after initialization with...

shift_register.set_daisy_chain(3) # Any positive int

Usage

Set Values with a List:

Will accept both Integers (1 and 0 only) as well as Boolean values (True and False)

shift_register.set_by_list([0, 1, 0, 1, 1, 1, 0, 0])
shift_register.set_by_list([False, True, False,...])

Set Values with an Integer:

This was created with the intent to send a single 1 or 0 for on or off, but can also function with a larger int as it converts to binary

shift_register.set_by_int(0)
shift_register.set_by_int(1)

shift_register.set_by_int(12) #1100
shift_register.set_by_int(9999) #1111100111

Set Values with a Boolean:

Can send a single True or False for on or off.

shift_register.set_by_bool(True)
shift_register.set_by_bool(False)

Clear All Current Values:

Sets each value to off (0)

shift_register.clear()

Get All Current Values:

Returns the current values

shift_register.get_values()
[0, 0, 0, 0, 0, 0, 0, 0]

Good 74HC595 Tutorials

It took me a while to finally understand how the 74HC595 worked since I had no prior hardware experience. These are the tutorials I used to understand the shift register.

Great but with Arduino

Good and with Raspberry Pi

Credits

License

MIT License. Please see License File for more information.

Project details


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