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AT89Sxx Cheap and Simple Learning Board

A Circuit or learning MCS-51 Microcontrollers.

The AT89Sxx learning board features,

  • Designed for new ISP chips, 89S51, 89S52, and 89S53, 40-pin DIP,
  • In System Programmable (ISP) through the 6-pin header and a jumper, (no need external programmer),
  • TxD and RxD serial port for communicating with serial devices,
  • 32 bit GPIO,
  • Onboard rectifier and +5V DC voltage regulator,
  • Single Sided PCB design.


The board design is kept as simple as possible so that everone can make the learning board easily. The schematic shown below shows the complete hardware schematic of the AT89Sxx learning board. PORT0, PORT1, PORT2, and PORT3 are available for interfacing external devices. P3.0 and P3.1 are being used for RS232 interface.


R1 330 1/4W +/-5%

R2 10K 1/4W +/-5%

R3-10 10K 1/4W +/-5% (for pull up on P0)

C1 1000uF/16V electrolytic capacitor

C2 100uF/16V electrolytic capacitor

C3 100nF multilayer or ceramic

C4 10uF/16V electrolytic

C5,C6 33pF ceramic

D1 1N4001 / 1N4002 silicon rectifier diode


U1 LM7805, voltage regulator

U1 AT89S51, AT89S52 or AT89S53

X1 Crystal 1MHz – 33MHz (11.0592MHz is suitable for standard BAUD rate generator using timer1, says 9600 )

DB25 parallel port, 25pins connector

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