Forums / 8051 Discussion Forum / 7 Segment Display connection... - Rickey's World of Microcontrollers & Microprocessors

Discussion in "8051 Discussion Forum" started by Adinarayanan Feb 21, 2009.

Adinarayanan

[ Fresher ]

Sat Feb 21 2009, 04:22 am

Hello...

I have a seven segment display LT 542
It is of common anode type.

I want to know weather i need to connect resistor to the common pin(3 and 8) and connect to Vcc and other pins directly to the ports of a controller or i need to use resistors for other pins also. Also in the place of resistors can i use a buffer ic say 74LS07.

Please help me....Thank you!

ajay_bhargav

Site Owner

Sun Feb 22 2009, 02:06 am

connect common to VCC via resistance and other pins to controller port. keep resistance about 680ohm.

Arun Kumar V

[ Member ]

Sun Feb 22 2009, 09:07 am

its always advisable to have individual resistors for each segment than one common resistor connected between Vcc and Common bcoz the display will appear dim/faint when numbers like '8' '9' '0' are shown and appear bright when numbers like '1' '7' are shown. also the segment leds will not share equal current if you use a single resistor.

its O.K to use single resistor for quick testing but for final assembly use separate resistors with a value of 330R or 470R

Arun

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