This is a step-by-step guide that I have created for beginners and arduiNOOBS like me.

In this tutorial, we would be discussing some pretty basic knowledge about the 8-bit shift register called 74HC595. Learn how to daisy-chain them together and use some codes from an HC595 Library.

Also, I encountered a problem with some of the shift registers. I don't know why. Was it because of lack of power?

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NECESSARY LINKS:

HC595 Library - https://github.com/j-bellavance/HC595

Datasheet - http://www.ti.com/document-viewer/SN74HC595/datasheet/specifications#SCLS0419845

More Information: https://rastating.github.io/using-a-74hc595-shift-register-with-an-arduino-uno/

For Loop Iteration: https://www.arduino.cc/en/Tutorial/ForLoopIteration

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Social Media Links To Follow (I mean, if you want to):

Facebook - https://fb.me/HeathenHacks

Twitter - https://twitter.com/HeathenHacks

Instagram - https://instagr.am/HeathenHacks

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Deep Daisy-Chaining: Shift Register Expansion

An Arduino Uno has 14 Digital pins. If you want to light up 32 separate LEDs independently (like for a massive LED cube or a flight-simulator dashboard), you physically cannot. This project introduces the foundational computer science concept of Serial-To-Parallel conversion, cascading to massively expand output limits using only 3 physical pins from the Uno!

The Synchronous Cascade Protocol

The 74HC595 chip has 8 Output pins (Q0-Q7), but uses 3 Input pins (Data, Clock, Latch).

1. The Daisy-Chain Physics: You physically wire the Q7' (Serial Out) of Chip #1 directly into the Data Pin of Chip #2!
2. You tie all 4 Clock lines together, and all 4 Latch lines together. You now have a unified 32-bit hardware block!
3. The Data Pipeline execution: To turn on LED #32, the Uno must physically pump 1 down the line. It goes into Chip 1. Then we push thirty-one 0s. The 1 is mathematically shoved exactly all the way down the electronic pipe into Chip 4, position 8!

The shiftOut() Register Bit-Masking

You cannot send decimal numbers trivially; you must use shiftOut().

• The loop() uses a massive 32-bit unsigned integer (or four 8-bit Bytes)!

  uint32_t ledMatrix = 0b10000000000000000000000000000001; // Lights the FIRST and LAST LED!
  
  digitalWrite(latchPin, LOW); // Pause the physical output! Freeze the LEDs!
  // You must split the massive 32-Bit integer into Four 8-Bit chunks to send down SPI!
  shiftOut(dataPin, clockPin, MSBFIRST, (ledMatrix >> 24)); // Shift Chip 4!
  shiftOut(dataPin, clockPin, MSBFIRST, (ledMatrix >> 16)); // Shift Chip 3!
  shiftOut(dataPin, clockPin, MSBFIRST, (ledMatrix >> 8));  // Shift Chip 2!
  shiftOut(dataPin, clockPin, MSBFIRST, ledMatrix);         // Shift Chip 1!
  
  digitalWrite(latchPin, HIGH); // The shift is done! Violently blast the 32 LEDs on!
  

• The execution is so unbelievably fast that it appears perfectly instantaneous to the human eye, enabling you to run huge Knight-Rider sweeping arrays seamlessly across all 32 LEDs!

Cascading Hardware Demands

• Arduino Uno/Nano (Standard functionality).
• Four 74HC595 Shift Register Integrated Circuits (DIP Packages).
• 32 Red/Green/Blue 5mm LEDs.
• 32 Generic 220 Ohm Resistors.
• A 5V 3-Amp Power Brick (If you blast all 32 LEDs to maximum brightness simultaneously, the Uno's internal regulator will instantly crash!).