[SOLVED] connecting microcontroller to seven segment led..??

hey dear friends..

I am a beginner in electronics project and m stucked in some silly basic questions.. please help me out..

I have to connect my 7 segment display to my microcontroller i.e. of pic16f series.. with source and sink current being 25 mA, and the forward current of my led is 20 mA, of 1 digit and i m using 4 digit 7 segment led .. how do i connect the led to my microcontroller
I know i need to add a device to decrease the current from led as they are 4 digits each carrying If = 20 mA... so as to protect the microcontroller, wat will be the difference if i use a resistor or a shift resistor... and wat else can i use here...
its a common cathode type led... i am also facing problem in connecting the enable pin there are total 10 pins in my 7 segment led 7 pins for 7 segments , 1 pin for dot and 2 enable pins.. how do i connect the two enable pins to my microcntroller..
here i googled and found out that i can use a transistor and a resistor to each enable pin separately which 'll go to microcontroller but then which type of transistor and how shall i connect it ..
what parameters shall i go through ... please help me out...?
if possible can anyone send me a link to any article related to the internal structure of a 7 segment display both common cathode and anode type.....

awaiting response...

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refer this site for help
PIC Tutorial  Ten - 7 Segment LED's
Interfacing Seven Segment Displays | eXtreme Electronics

sir can u please help me out with how to connect transistors as invertors..??

i need ur help with this para as to hw do i relate it to my task

"To reduce the pin count required, the two displays are multiplexed - this means we need seven I/O pins, one for each segment of the LED (ignoring the decimal point), and two to select the individual sections - unfortunately this would require nine I/O pins - taking more than one port. To over come this I've designed the 7 segment board to select the two sections using just one pin - the two transistors are wired as inverters, this means that when Q1 is ON, Q2 is OFF, and when Q1 is OFF, Q2 is ON - so by switching port pin 7 we can alternate between the two sections."

mine is a four digit led hw do i connect the transistors how 'll the switching tale place in my task.. sir i 've understood the function but i am getting difficulty in connections.... how will i connect the transistors .....

Pic Microcontroller P16F84 Tutorial: Seven-Segment Display Example : 8051 Microcontroller Projects AVR PIC Projects Tutorials Ebooks Libraries codes

Go threw this link... it may usefull to you

Better to use a BCD to seven segment decoder..its easy and consumes only part of ur Ports

sir can u please help me out with how to connect transistors as invertors..??

i need ur help with this para as to hw do i relate it to my task

"To reduce the pin count required, the two displays are multiplexed - this means we need seven I/O pins, one for each segment of the LED (ignoring the decimal point), and two to select the individual sections - unfortunately this would require nine I/O pins - taking more than one port. To over come this I've designed the 7 segment board to select the two sections using just one pin - the two transistors are wired as inverters, this means that when Q1 is ON, Q2 is OFF, and when Q1 is OFF, Q2 is ON - so by switching port pin 7 we can alternate between the two sections."

mine is a four digit led hw do i connect the transistors how 'll the switching tale place in my task.. sir i 've understood the function but i am getting difficulty in connections.... how will i connect the transistors .....

Click to expand...

Here's the way

I agree with master sreepss.. BCD to seven segment will lessen the number of your'e pins to drive the 7 segment LED's... or you can also use multiplexing through transistors as described by master Ajish..