The output of 8051 micro controller is active high so we must need to use the common cathode type display . it will work glow when any input is high . The anode terminals of leds's of seven segment connected to 8051's output and cathode is common and grounded . so it require common cathode because 8051 provide active high output.
To connect a common anode 7-segment display, you would typically connect the common anode pin to a positive voltage source and the individual segment pins to current-limiting resistors connected to the microcontroller output pins. When you provide a LOW signal to a segment pin, it will turn on that segment.
You should use a mechanism called persistance of vision for interfacing multiple seven segment displays. here is tutorial for mulplexing displays using 8051 microcontroller. http://www.shree-electronics.com/interfacing_multiple_7_segment_displays.htm
When using a common cathode 7-segment display with a 7447 the readout is inverted. Instead of 1000 resulting in an 8, you will see all segments will be off. Since a common cathode display pulls its power from the driving IC chip you could either use an inverter on each input segment or use each 7447 output to forward bias a transistor (turn it on) allowing current draw to come directly from Vcc instead of risking burning out your chip. Note: the series limiting resistors will still be necessary.
A schematic diagram for a countdown timer typically includes a microcontroller or timer IC, such as the 555 timer, along with a display unit (like a 7-segment display or LCD), and input buttons for setting the time. The circuit may also include resistors, capacitors, and possibly a buzzer for alarm functionality. The microcontroller receives input from the buttons to adjust the countdown duration and controls the display to show the remaining time. Additional components might include power supply connections and protective diodes.
A seven segment display is a device used to display numbers and letters on things such as alarm clocks. A 7 segment display is simply seven LED's packaged in a pattern that allows numbers and letters to be displayed by illuminating different sets of LED's.
A: NO it is a display of seven segment to display a decimal of '0' to '9' it may have 8 LED for the point
Seven Segment Display
We cannot connect the 74ls138 straight with a seven segment display; for that we need a 7447(7 segment driver).
A 7 segment display is an I/O device, and it is not necessarily used in microprocessors. The choice of I/O devices is a function of system design, not microprocessor design.
The Eustachian Tube
if we r connecting all anode pins of 7 segments.. It is called common anode.Common Anode 7-segment displayThe Anode, or (+) is supplied, ( pins 3,8 are connected to + through a resistor)So if any of the input pins to turn on the segments go low, they will complete a circuit from (-) to (+) and light a light.For example if there is a low signal (-) on pin 10 the G line in the middle will light up.if we r connecting all cathode pins of 7 segments.. It is called common cathode.Common Cathode 7-segment displayThe Cathode, or (-) is supplied, ( pins 3,8 are connected to - through a resistor. )So if any of the input pins to turn on the segments go high, they will complete a circuit from (+) to (-) and light a light.For example if there is a high signal (+) on pin 10 the G line in the middle will light up.Manimran.RNagoba Electronics,Bangalore.
it is three digit seven segment display driver IC