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Drive output to LEDs

valleytech asked
Last Modified: 2010-04-26
Hi all,
  I have a bread-board and LEDs on it. I don't know how i can drive my program's output to make those LEDs blinking. Could you please tell me
       + What kind of connector to i need to buy in order to connect my bread board to the system ?
       +  Which port can i make that kind of connection?
       + How can i control the LED from my program ?
 Also, i don't know where to start.
   Please let me know in details since i never do any kind of stuff like this. Thanks for your patience.
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Could you please move it to the hardware section. Thanks a lot.
PS: what kind of connector do i need to buy?
Top Expert 2012

Are you sure you want to deal with hardware at such a primitive level?  LCD Smartie (http://lcdsmartie.sourceforge.net/) is open source and lets you control an LCD display in a much easier way - unless you're doing this to learn about controlling LED displays and not to actually build something for practical use.


 The LEDs in the bread board will just blink. Honestly, i want to learn how to control it by C, C++, or MFC => so i can use LCD Smartie after I understand the concept. Thanks.

  After i buy a RS232, what should i do next? What issue should i focus on software? Thanks.
Simplest way is to use the parallel port, I think you can get up to 13 LEDs working off it if you abuse some of the status and control lines. But 8 would probably be easier. If they're low output LEDs I think you can just drive them straight off the parallel port, high output ones might suck a bit too much and you'd need to use a buffer. Probably best to use a buffer anyway, if you're using the motherboard parallel port.


i have 2 bread boards. For each bread board, i have:
    +  4 yellow leds
    +  4 green leds
    + 4 read    leds

=> total i have 24 leds.
  I group them differently. Yellow leds connect to yellow, red ones to red ones...
  So i have 4 power lines totally. One for GROUND, one for YELLOW Leds, one for GREEN leds, and one for RED leds.
  I just wonder i should use serial port or parallel port?  It seems to me that serial port can have enough current to drive all the LEDs.
  Any advise is appreciated.
Top Expert 2012

All the LCD and VFD devices I have seen use the serial port or USB port and draw power from a standard PC molex connector (+12v, +5v).  Since LCD Smartie is open source, you can look at the code to see how it is done, although it is a lot more complex than simply turning on and off LEDs.


I just wonder that after i buy RS232 plug, what should i do next in order to use LCD Smartie. I have no idea how i start since this is my first time to work on it.
Could you please tell me step-by-step ? Thanks.
Top Expert 2012
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Thanks lot. I will read it.
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