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hi all

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TKS

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Hi all,

i don't have much knowledge of electronics...(and that's comig up now)

how can i best make use of a Led display (the ones that you use to show up numbers, they are build with leds...cathode commun or anode commun)

wich chips i need to use them in a simple way?

i need to drive 8 of them and a Led bar....
its for a Car dash that i'm making...

if anyone has a good project (with a microcontroller) wich makes use of such a thing (not using the microcontroller offourse for the output) it woul dbe great.

i can offcourse use 16F84A's (and build a network) one per segment but i don't think it is needed..

can i use DAC's?? (but offcourse i only need a 1 or a 0 not 4,98844 volts...
soow its to much..)

TKS
 
why dont you use an LED bar display insted of an 7 segment display(the ones that show numbers)

as you know you need an programer and know how to porgram PICs
 
uhh

i know how to program a pic

what i don't know: what do i need to drive that segments things..
(like in digital clocks near your bed).

look i need to drive allot of them soo i search for an hard way and not the simple way to drive them one of each output pin of the pic untherstand??

i think i need a hex schifter or something but wich one i have no idea..

i need to drive:

- 20leds needed 20 outputs
- 2x 2 led segments 24/2 = 28ouputs
- 7x 1 segment 7/3 =21outputs
- 1x led bar (10leds) 10 outputs

i have 1 MCU Pic16F877a (40 pins)

untherstand?? its more that i'm searching for a analog way to switch these things.. or that ever segment only uses 2 of the pic (like control lines) and that another chip does the display/activation of the leds...

hope that everybody untherstands me now better

TKS
 
Look at the pic..:D

TKS
 

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Re: uhh

TKS said:
i know how to program a pic

what i don't know: what do i need to drive that segments things..
(like in digital clocks near your bed).

look i need to drive allot of them soo i search for an hard way and not the simple way to drive them one of each output pin of the pic untherstand??

i think i need a hex schifter or something but wich one i have no idea..

i need to drive:

- 20leds needed 20 outputs
- 2x 2 led segments 24/2 = 28ouputs
- 7x 1 segment 7/3 =21outputs
- 1x led bar (10leds) 10 outputs

i have 1 MCU Pic16F877a (40 pins)

untherstand?? its more that i'm searching for a analog way to switch these things.. or that ever segment only uses 2 of the pic (like control lines) and that another chip does the display/activation of the leds...

hope that everybody untherstands me now better

TKS
Try using M5451B7, this IC can drive up to 35 leds, has serial input...
 
mhhh..

but it costs 5euro's! i need 3 of them min. that's 15euro's!!!!

will look @ the hassle of using 16F819 (built in OSC 8Mhz)


but thanxs the key word was Led drivers..ok

thanxs..

think i will buy them anyway because its faster..and speed is..money to..:D


TKS
 
TKS said:
mhhh..

but it costs 5euro's! i need 3 of them min. that's 15euro's!!!!

will look @ the hassle of using 16F819 (built in OSC 8Mhz)


but thanxs the key word was Led drivers..ok

thanxs..

think i will buy them anyway because its faster..and speed is..money to..:D
TKS
Strange, it costs 128SK, that's 2.8 Euro here... (including VAT). And I thought that IC's in my country are expensive :lol:
 
In my cuntry they are expensive.


there is a neat trick how to run leds on an lower amout of pins!(Almost all VFD displays work in this way)

This your PIC has PORTA,PORTB,PORTC,PORTD.Right?So whithout PORTA you cod drive 128 LEDs

the trick is that you break it on to segments and have PORTB for exsample thurn those segments on/off and the other ports can cotrol only the segment that is on

so i ges like this:
each segment has 16 Leds
PORTB contols the catodes of LEDs
and the other ports control the anodes of LEDs in each segment
PORTB thurns segment 1 on and other ports thurn the LEDs on
then PORTB thurns segment 2 on and other ports thurn the LEDs on
this goes on thil the segment 8 (porobly les since you dont have 128 LEDS)and then repets this goes so fast that you think that an LED is on
 
Someone Electro said:
In my cuntry they are expensive.


there is a neat trick how to run leds on an lower amout of pins!(Almost all VFD displays work in this way)

This your PIC has PORTA,PORTB,PORTC,PORTD.Right?So whithout PORTA you cod drive 128 LEDs

the trick is that you break it on to segments and have PORTB for exsample thurn those segments on/off and the other ports can cotrol only the segment that is on

so i ges like this:
each segment has 16 Leds
PORTB contols the catodes of LEDs
and the other ports control the anodes of LEDs in each segment
PORTB thurns segment 1 on and other ports thurn the LEDs on
then PORTB thurns segment 2 on and other ports thurn the LEDs on
this goes on thil the segment 8 (porobly les since you dont have 128 LEDS)and then repets this goes so fast that you think that an LED is on
The big advantage of using M5451B7 is that it's driving LED's in STATIC mode, and that it has serial input, therefore you can controll it by small 8-pin PIC, and static mode brings you non-blinking pattern.
And it's much easier to implement it than Charlie Plexing, which takes a tone of CPU time...
 
Hey buddy,have you ever seen how a dot matrix LED panle works?If you ever have,you make use that structure to drive your LEDs.One single MCU can drive up to 512*128 pixles or more,and that's more than 65536 LEDs,which is far more than your requirement.The key that such circuitry would work is the latches.A series of latches connected in serial can extend your I/O resources more than 10 times of the original.Try 74LS595.It's an 8 bit serial-in,parallel-out shift register with output latches.Use an I/O pin of your PIC to switch in serial data synchronized by a serial clock generated by another I/O pin.Each bit will be sent to the cathode of an individual LED while all anodes are conncted to Vcc via resistors.When all bits are shifted out,use a third I/O pin to generate a register clock,and the data bits will be latched onto respective I/O pins.This output won't be modified before next register clock even when you are shifting another stream of serial data into the series of 595s.
I think this might help as I have built lots of dot matrix LED panels,and right now there is one above my computer that displays current time as a clock.
 
Alex_rcpilot said:
Hey buddy,have you ever seen how a dot matrix LED panle works?If you ever have,you make use that structure to drive your LEDs.One single MCU can drive up to 512*128 pixles or more,and that's more than 65536 LEDs,which is far more than your requirement.The key that such circuitry would work is the latches.A series of latches connected in serial can extend your I/O resources more than 10 times of the original.Try 74LS595.It's an 8 bit serial-in,parallel-out shift register with output latches.Use an I/O pin of your PIC to switch in serial data synchronized by a serial clock generated by another I/O pin.Each bit will be sent to the cathode of an individual LED while all anodes are conncted to Vcc via resistors.When all bits are shifted out,use a third I/O pin to generate a register clock,and the data bits will be latched onto respective I/O pins.This output won't be modified before next register clock even when you are shifting another stream of serial data into the series of 595s.
I think this might help as I have built lots of dot matrix LED panels,and right now there is one above my computer that displays current time as a clock.
Wow :shock:
Don't flame me, I just supposed that it's easier to use this IC for *BEGINNER*, I know multiplexing and Cherlieplexing are better to use with dot pixel and other Big, high count LED panels.
 
:? Oh,First my appologies for being confusing.Actually I was calling TKS "buddy" and telling him about dot panels.Your idea was also good Jay.I wasn't trying to deny it,but giving another suggestion.Your solution would fit this case better :)
 
Alex_rcpilot said:
:? Oh,First my appologies for being confusing.Actually I was calling TKS "buddy" and telling him about dot panels.Your idea was also good Jay.I wasn't trying to deny it,but giving another suggestion.Your solution would fit this case better :)
Oh my, no problem. I thought you said my solution was bul*. And I was thinkin' why are you so mean. Well everything is OK now. :lol:
 
Jay,I ought to be more careful in future :) .
TKS,I'm really curious about why you need all kinds of such LEDs lit in one single device.What do you want to display anyway?If you're going to use the segment LEDs to display numbers,in Jay's way,I think it's best to place them in a separate module,that will may table translation routines easier to write.You may use 8 pins of a port to drvie the segment LEDs' cathodes in parallel,and other ports to control other functions,including module selection.
 
Hey TKS, are you going to put a cover over it or leave it kind of raw like that? I'd be interested to see how it looks when it's lit up in the car.
 
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