Importance of a Digital Speedometer

A digital speedometer is commonly found in land vehicles such as cars, trucks, vans, motorbikes, and other similar types of transportation. However, it can also be used for other means as well. It can be applied to anything wherein one is measuring the speed of a specific moving object. It is a vital instrument especially when it comes to land vehicles. With it, the driver or operator of the machine is able to track his or her movement and maintain a relatively safe speed while on the road. When it comes to racing performance vehicles, it is used by the driver and technicians to make vital decisions and measure the overall performance of the machine.

In a car, the digital speedometer actually measures the rotational speed of the wheel or how fast the wheel turns. Unlike with the old, analogue speedometers, this does not make use of moving pointer displays or the moving magnet designs. Instead, it makes use of a digital screen readout to show the driver a more exact and accurate reading of the vehicle’s current speed. Obviously, the advantage of this is that the driver can tell exactly how fast he or she is going and not have to rely on needles and indistinguishable lines between numbers.  

The design of the digital speedometer does not call for a lot of new parts. In fact, it makes use of just a few components which makes it simple to install one in your car. All it needs is a microcontroller, an IC1, a drives IC3, and a two row LCD which supports sixteen characters. All of these components are attached to a PC board. Then, you have two components outside of the board; namely, the IC4 and the sensor used to measure the rotation speeds of the wheel. The most common type used in this design is a hall effect sensor and is placed close to the periphery of the vehicle and at a fixed distance from the wheel’s axle.

A magnet is then attached to one of the wheels of the vehicle. Whenever it rotates, it will pass by the sensor in each complete rotation, thus activating the component. Once this happens, it creates a small pulse, indicating one full revolution of the wheel. This is then turned into a high priority interrupt by the digital speedometer. The speed of the vehicle is then calculated by the AVR based on the time elapsed between two high priority interrupts. It then displays this on the LCD screen for the driver to recognize. 

Again, the importance of this is that it gives the operator the ability to accurately depict his or her speed on the road. Knowing this can greatly help in ensuring one’s safety. Another plus side of the digital speedometer is that it can also measure the distance travelled by the vehicle from the moment you started your engine to the time you turn it off. It can also be calibrated in such a way to show the speed reading in KPH or MPH and the distance in kilometres or miles.