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Embedded Interface – MCP23017


  • 16-bit input/output port expander with interrupt output
  • 16 bit serial interface
  • Cascadable for up to 8 devices on one bus
  • 25mA sink/source capability per I/O
  • Supports 100kHz, 400kHz and 1.7MHz I2C™Compatible compatible modes


Pin Details


  • There are two interrupt pins, INTA and INTB, that can be associated with their respective ports, or can be
    logically OR’ed together so that both pins will activate if either port causes an interrupt.


  • system master can enable the I/Os as either inputs or outputs by writing the I/O configuration bits
    IOCON.BANK – The MCP23X17 can beconfigured to operate in the 8-bit or 16-bit modes via “IOCON.BANK.”

Data Sheet :

  • 2005-2016
  • 2007


  • Interfacing a 4×4 Matrix Keypad with an 8-Bit GPIO Expander
  • Expanding the number of I/O lines using Microchip MCP23008
  • Unique Features of the MCP23X08/17 GPIO Expanders
  • MCP23008 port expander interfaced to PIC12F683

reference Link



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Embedded Interface – EEPROM

Getting Started With AT24C128 I²C EEPROM


  • Voltage
    • Low Voltage (1.8v to 3.6v)
    • Standard Voltage (2.7V to 5.5V)
  • Memory
    • 128K (16,384 x 8)
    • 256K (32,768 x 8)
  • I²C Interface (Bi-Directional data transfer protocol)
  • Speed
    • 1MHz(5v)
    • 400KHz(2.7v, 2.5v)
    • 100kHz(1.8v)
  • High Reliablility
    • 1 Million write cycles of endurance
    • 40 years of Data Retention

At First Lean this


Useful Resource

 See Also


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Embedded Interface – LCD


  • Display Character
  • Display String
  • Display Decimal
    • Display one Digit Decimal
    • Display Two Digit Decimal
    • Display Three Digit Decimal
  • Auto scroll Display
  • Blink
  • Cursor On/Off
  • Custom Character
  • Display
  • Hello world
  • Scroll
  • Serial Display
  • Set Cursor
  • Text Direction

LCD Interface with Micro-controllers

Different LCD Displays

  • Nokia 5110 LCD Module with PCD8544 
  • Nokia 6610 
  • OLEDs 
  • 2×16 LCD- hd44780 
  • Nextion Display 

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Embedded Interface – Button


  • LED ON/OFF Using Button
  • Button De-bounce
  • Four Button (UP, DOWN, ENTER, BACK)
    • Set Value By Four_Buttons using 7 Segment Display
    • Set Value By Four_Buttons using LCD Display
  • Matrix Keypad
    • Set Value by Matrix Keypad using 7 Segment Display
    • Set Value by Matrix Keypad using LCD Display
    • Display characters by Matrix Keypad using 7 Segment Display
    • Display characters by Matrix Keypad using LCD Display

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Embedded Interface – LED

 LED (Light Emitted Diode)

LED Symbol


How to Identify the LED Positive and Negative Leads ?

  • Long lead is positive(+) and small lead is negative(-)
  • Round circle lead is positive(+) and flat lead is negative(-)


LED Chemical Substance

Summary of LED Colors and Common Chemistries

Color Wavelength Materials
Amber 605-620 nm Gallium arsenide phosphide, Aluminum gallium indium phosphide
Blue 430-505 nm IInGaN (Indium Gallium Nitride), Gallium nitride, Silicon carbide, Sapphire, Zinc selenide
Green 550-570 nm Aluminum gallium phosphide, Gallium nitride
Infra-Red 850-940 nm Gallium arsenide, AL GaAs (Aluminum Gallium Arsenide)
Red 630-660 nm AL GaAs (Aluminum Gallium Arsenide), Gallium arsenide phosphide, Gallium phosphide
Ultraviolet 370-400 nm Indium gallium nitride, Aluminum gallium nitride
Violet 410-420nm
Yellow 585-595 nm Aluminum gallium phosphide, Gallium arsenide phosphide, Gallium phosphide


LED Light wave length
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410nm-420nm(violet) Skin therapy
430nm-470nm(blue) Dental curing instrument
470nm(blue) White LED’s using phosphor, blue for RGB white
520nm-530nm(green) Green traffic signal lights, amber for RGBA white lights
580nm-590nm(amber) Red signal lights, red for RGBA white lights
630nm-640nm(red) Blood oximetry
660nm(deep red) Skin therapy
680nm(deep red) Night vision illuminators and beacons for use with night vision goggles or CCD’S
800nm-850nm(near IR) Photo electric controls
940nm(near IR) Convert illumination CCD based systems


Reference  :






LED Blink


LED Application

  • Status Indicator
  • WiFi Router Status Indicator (Blink LED-Internet Status)
  • Charge level Indication in mobile power-bank [Blink LED – Single RGB LED or Multiple Color LED)
  • Bike Automation
    • Bike Turn Indicator (LED Blink – while turned)
    • Bike Side stand indicator (LED Glow -if Side stand is not took)
  • Car Automation
    • Car Turn Indicator (LED Blink – while turned)
    • Car Door Status indicator(LED Glow -if Door is not close or opened)


  • LED Blink using Delay Function
  • LED Blink using Timer Function
  • LED as a Status Indicator(Using condition Check)Button

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