user Electronics Engineer

city Innovuze Solution Inc.

  • Sports Watch circuit diagram

  • Created: Apr 27, 2016

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Since before, man has been trying to measure time. They manage to measure by using the position of the heavenly bodies such as the sun, the moon, and the stars in the sky. Man was able to build their first clock, the sundial clocks. Then the evolution of technology went on to mechanical clock, analog, and digital. Together with the evolution of time, man understood the importance of measuring time in their day-to-day life, tracking time of how fast and how long they can do things in a certain amount of time. This circuit is a simple digital stopwatch, with the tactile switch used for mode configuration for the stopwatch. The tactile switch used is the TL3365AF180QG, which is an ultra miniature switch that can easily be used in compact circuitry. It has an electrical rating of 50mA at 12VDC.

The circuit has a +5V regulator, a 16 x 4 LCD Display, an ATmega8535, and 4 TL3365AF180QG tactile switch. The circuit has two timing modes, namely “Split timing” and “Lap timing”. In split timing mode, when the time is split, the instance of splitting is shown in the LCD display and the timer will continue. In lap timing, when the timing is lapped, the timer is restarted after showing the lapping instance in the LCD display. The user must select a timing mode when the circuit is switched “on” before the timing can start. The selection can be done by, pressing the tactile switch connected to either Port_C0 for Split timing (S1) or Port_C1 for Lap timing (S2). The switch (S3) connected to Port_D2 uses the Interrupt 0 of the atmega8535 for the start and stop timing. The last switch (S4) is connected to Port_D1; it uses the Interrupt 1 of the atmega8535 for the reset, split and lap timing, which is different from mode selection. A de-bouncing is used when a switch is pressed.

The circuit is a digital stopwatch, which is more accurate than the mechanical devices. Since digital stopwatches are more accurate and portable, it is applicable in situations when time must be measured precisely like, experiment in science project, sport, and your day-to-day activity.



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