Introduction into 8051 microcontroller architecture using W78E052


The Intel MCS-51 (commonly known as 8051) is an 8bit microcontroller with Harvard architecture, complex instruction set computer (CISC) instruction set developed by Intel in 1980 for use in embedded systems.While Intel no longer manufactures the MCS-51 family, enhanced binary compatible derivatives made by numerous vendors remain popular today


  • AT89S51,AT89S52
  • P89V51RD2
  • W78E052DDG

Main Features of MCS51(8051) Architecture

  • 8-bit arithmetic logic unit (ALU) and accumulator, 
  • 4 fast switchable register banks with 8 registers each (memory mapped)
  • Fast interrupt with optional register bank switching
  • Interrupts and threads with selectable priority
  • Dual 16-bit address bus 
  • 4 KiB of on-chip ROM, with a 16-bit (64 KiB) address space (PMEM). Not included on 803X variants
  • Four 8-bit bi-directional input/output port, bit addressable
  • UART (serial port)
  • Two 16-bit Counter/timers
  • Power saving mode (on some derivatives)

Which 8051 derivative are we using in this tutorial?

Here we are going to use W78E052DDG 8051 derivative from Nuvoton.The microcontroller comes in a 40 pin DIP package that is pin compatible with other standard 8051 derivatives like AT89S52,P89V51RD2 etc.

Nuvoton W78E052DDG 8051 derivative microcontroller tutorial

The main features of the chip are the following.

  • 40 pin DIP package
  • 8 KB of Flash memory
  • 256B of SRAM
  • Four 8 bit Bi directional ports
  • 1 Full Duplex UART
  • Three 16bit timers/Counters
  • 8 Interrupt sources
  • Watch Dog Timer
  • Max frequency of 40 MHz

Here is the block diagram of the W78E052DDG 8051 microcontroller.

W78E052DDG 8051 micro controller  block diagram tutorial


8051 development board used 

Here we are going to use a " learning by doing philosophy " in order to study the 8051 architecture.Inorder to reduce the effort and maximize the efficiency of learning we are going to use a 8051 development board called 8052 Robotics Kit.

The board has a

  • W78E052DDg (8052 based) microcontroller
  • 8Channel ADC ,ADC0808/09
  • A L293D motor control chip
  • A FT232 based USB serial port
  • and a build in USB based In system programming circuit.

Below you can see the block diagram of the W78E052DDg based 8051 microcontroller development board.

8051(w78e052ddg) development board for robotics with usb based programmer


The board can be used to build a wide variety of embedded system projects using 8051 microcontroller like  

  • 8051 powered line following robot
  • 8051 based data acquisition system


You can buy the W78E052DDg based 8051 microcontroller development board from here.


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