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

[sapna.dudani@gmail.com]

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...

dont use sms format typing or short hand typing scripts in the forum..
this will lead to deletion of post and inviting infraction

 

[ckshivaram]

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

 

[sapna.dudani@gmail.com]

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 .....

 

[praveenlb]

 

[Senthilkumar_rjpm]

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

 

[sreepss]

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

 

[Embedded_Geek]

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 .....

Here's the way

 

[amadjo01]

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..