Sep232009

Taking power from PC serial port

Here's the circuit which can take power from the serial port. It can be used for driving low power microcontroller circuits. There are 2 circuits in which one use a zener diode as an regulator and other use IC7805 as an regulator. Remember to make the DTR and RTS pins of the serial port to be in High logic. [More]

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Sep232009

What is AT89S51

You may see this chip AT89S51 in many of the circuits in this site. What is this AT89S51. The first microcontroller chip was introduced in 1980 by Intel semiconductors. It is named as 8031. This 8031 does not have internal program memory. Then came the 8051 microcontroller which has internal prog... [More]

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Sep222009

Maximum baud rates for various crystal values

Here's the maximum baud rates for various crystals with their error values. Smallest commincation errors are obtained only with the 11.0592M and 22.1184M crystal values. So these 2 values are mostly used. [More]

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Sep212009

A Simple 8051 based ATAPI CDROM audio controller

Connect your old CD Rom to your AT89S52 microcontroller and make a simple audio player. You can now control the cd rom with all the options such us play, stop, next, previous through your 8051 microcontroller. [More]

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Sep162009

Digital Clock with AT89S51 without RTC chip

Digital Clock with AT89S51 without RTC chip. Here's an digital clock project which does not use any Real Time Clock (RTC) chips. This is made with the AT89S51 microcontroller. The assembly language & C program is given here. The circuit starts displaying 12:00:00 at starting. The switch SP1 is for changing the Seconds, SP2 for Minutes and SP3 is for changing the Hours. [More]

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Sep152009

6 digit Frequency counter using AT89S51

This project is done with help of AT89S51 microcontroller. The T0 & T1 timers of the At89s51 is used to measure the frequency of the input clock. This project can measure clock frequencies upto 250Khz. [More]

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Sep122009

Watchdog Timer

I am considering a P89V664 microcontroller which has an inbuilt 14-bit watchdog timer. The code is written on SDCC and can be used on kiel with slight changes. [More]

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