In order to turn on a particular segment, a ground level voltage is given to the corresponding pin. It should be connected to a high voltage (to the supply through a resistor to limit current).

According to the pins which are connected to the common terminal, the seven segment display is categorized as a common anode and common cathode. One pin each from each segment is connected to a common terminal. They are the common anode and a common cathode. Seven segment displays are seen associated with a great number of devices such as clocks, digital home appliances, signal boards on roads etc.Īs mentioned in previous paragraphs, seven segment displays come up with two different configurations. To overcome the forward voltage drop, the voltage supplied should be greater than the actual forward voltage value. To limit forward current, a series resistance is connected to the voltage supply. Since the light emission is directly proportional to the forward current, it is necessary to control the forward current according to the requirement of light emission. It was mentioned earlier that the LEDs emit light only when it is forward biased and the amount of light emitted is proportional to the forward current. Out of many types of segment displays available, this is the most common form. These seven LEDs indicate seven segments of the numbers and a dot point. Seven segment displays can only display 0 to 9 numbers. Other pins are connected together to a common terminal. Sometimes, an additional LED is seen in a seven segment display unit which is meant for displaying a decimal point.Įach LED segment has one of its pins brought out of the rectangular package. In a seven segment display module, seven LED s are arranged in a rectangle. The light energy is emitted as ‘photons’ when it is forward biased by a voltage applied across its junctions. Because of the small size of the LEDs, it is really easy for a number of them to be connected together to make a unit like seven segment display. LEDs are PN-junction diodes which emit energy by a process called electroluminescence. Seven segment display modules are not a recent invention as it’s first applications were dated back as earlier as in 1910.Ī seven segment display module is an electronic device used to display digital numbers and it is made up of seven LED segments.

This chapter describes how a 7 segment display interfacing with pic microcontroller is being worked out.

8051 7 seg 0 99 transistor