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I've got a 12f683 and want to run 16 LEDs off it. I want one LED to be on for about 2 seconds then move on to the next. What is the easiest and cheapest way to hook them up?
I'd swear I saw an article that the maximum number of LEDs one could hook to a PIC was defined by 2 raised to the number of pins available. That would mean a 12f683 is capable of controlling 64 LEDs (2 to the 6th).
Is that true?
Tip #2 should be what you need.
http://www.picbasic.co.uk/forum/cont...ips-and-Tricks
Adding column drivers to a Charlieplexed matrix allows lighting multiple LEDs in each column to increase duty cycle and brightness. If you're only going to light one LED at a time you can eliminate the column driver transistors.
With Charlieplexing you get N(N-1) outputs (N = number of pins)...
Regards, Mike
Using the circuit from Tip #2 with the LEDs on the ICSP pins I get a wrong chip selected error. On the 12f683 I have GP0 on pin 7 and GP1 on pin 6. Pin 4 is pulled high with a 500 ohm resistor. It seems the programmer is only picky about pin 7 being used.
Tip #2 should be what you need.
http://www.picbasic.co.uk/forum/cont...ips-and-Tricks
How can I connect LEDs and the ICSP header on the same pins?
As usual, your thoughts are surely better than mine.
Sometimes a resistor in series from the programing pins to the application circuit works, sometimes diodes.
The sure fire way is to use a removable jumper to disconnect the programing pins from everything else while programing.
If you are using the PicKit2, the PicKit2 User Guide briefly mentions this.
Remember that most 12Fs usually have an input only pin (mclr/gp3) but yes with charlieplexing and driving your leds at a higher current / lower pulse width should do the trick.
Anyway if you want more and more outputs, just use a 74HC595 connected to the 12F combined with shiftout command for an unlimited number of them if your timing allows them to refresh