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Simple digital stopwatch using at89s51 Microcontroller

Here's a simple digital stopwatch with AT89S51 microcontroller. Two common cathode type 7segment displays are used to display the time.
Operation:
• The display will show 00 at the startup
• Press the switch SP1 to get the watch to run
• Press the switch again to stop the watch
• To start the watch press the same switch again