Making a 74HC595 LED driver for Arduino PIC and AVR

LEDs Driver Making

As referred in the previous post, I made a single seven segments board based on SN74HC595N.

Here, I make a similar one, but the 74HC595 at this time drive 8 LEDs. It's just a simple example of using 74HC595 with Arduino. 

A sample of running program

 

I use Proteus 8 to design the schematic and PCB.

Schematic Diagram

 

I export the PCB pattern including copper track and legend side.

Copper Side

 

Top Silk

 

A 3D View

 

A completed Soldering Board

 

The Proteus design file could be downloaded here. 

Arduino Programming And Interfacing

I use the same shiftOut() function to transmit the data the registers. With and additional random() function to create a random numbers up to 255, and displaying it on LEDs.

The syntax of random() function is:

random(max)
random(min, max)

Where,

• min - is the lower bound value
• max - is the upper bound value

This function return a created random number as set. 

Arduino source code lists below.

 

Arduino sketch

 

Arduino sketch could be downloaded here.

 

We can use the ATMega32 microcontroller to interface to some serial to parallel shift registers chips.

1. ATMega32 Interfaces To SN74HC164 Shift Registers
2. ATMega32 SPI Interfaces To SN74HC164 And LED 
3. ATMega32 SPI Interfaces To SN74HC164 And LCD Using 3 Pins
4.  ATMega32 And SN74HC164 Serial Seven Segment Display
5. ATMega32 SN74HC164 Seven Segments Display And Switch Interfacing 
6. ATMega32 SN74HC164 Three-Digit Multiplexing Display
7. ATMega32 SPI Interfaces With SN74HC595 For Character LCD Controlling

A DIY TWI LCD Using PCF8574AP For Arduino

A character LCD with a 44780 LCD controller generally controlled by an MCU parallel port. Even the data transfer in-used is 4-bit mode, but it still require up to six MCU pins. 

A character LCD with PCF8574AP

PCF8574AP is an 8-bit general purpose digital I/O expanding. We can read and write digital data between this device and a master MCU, or even controlling a parallel LCD module. However using an I2C IC bridge the master MCU uses only two pins of its digital I/O to interface to the LCD.

In online market the PCF8574AP is built in module the a character LCD that cost a few Dollars. For an electronics hobbyist like me, I only bought a single DIP version of this chip. I can program it to read/write digital data before I decide to put it with a character LCD.

I decided to make my own I2C board module for my Arduino Uno board. This design follows the liquidCrystal_I2C LCD library from an author on GitHub. The overall design is not difference from the original one's but I made my own schematic and PCB design for my personal use.

I use Eagle CAD from Auto Desk software due to its richness of symbols and footprints library. The result yield with a small rectangular PCB module wired with PCF8574AP and a character LCD.

Schematic Diagram

PCB View

This design example is fully worked as I have tested it with Arduino Uno using its library.

A zip file of this design could be download here.

Connection Diagram

 

This Arduino sketch is from the library itself with some of my own modification.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// set the LCD address to 0x38 for PCF8574A with A0 A1 A2 wired to GND
LiquidCrystal_I2C lcd(0x38,16,2); 
void setup()
{
  // initialize the lcd
  lcd.init();                     
  lcd.backlight();
  lcd.clear();
  Serial.begin(9600);
  lcd.setCursor(0,0);
  lcd.print("Serial Port LCD");
}

void loop()
{
  // when characters arrive over the serial port...
  if (Serial.available()) {
    // wait a bit for the entire message to arrive
    delay(100);
    // clear the screen
    lcd.clear();
    // read all the available characters
    while (Serial.available() > 0) {
      // display each character to the LCD
      lcd.write(Serial.read());
    }
  }
}

This sketch could be download here, or you can get from the library after the installation.