8 pin DIP w/6 outputs ?

**Sam** · - 13th September 2009, 01:37

I have been searching Microchip.com and haven't found any 8 pin DIP PIC's with 6 output. The MCLR is always an input only, which I basically understand but is there any model with 6 outputs.

Thanks,

Steve

**mackrackit** · - 13th September 2009, 01:52

As far as I know you will always have Vdd, VSS and MCLR.

What are you trying to do? Maybe there is another solution?

**Sam** · - 13th September 2009, 02:10

The simple answer to that is, control 6 LED's separately with only a 8 pin DIP package.

**dhouston** · - 13th September 2009, 02:57

http://ww1.microchip.com/downloads/e...doc/40040b.pdf

And with one input to spare.

**Sam** · - 13th September 2009, 03:06

Originally Posted by Sam

I have been searching Microchip.com and haven't found any 8 pin DIP PIC's with 6 output. The MCLR is always an input only, which I basically understand but is there any model with 6 outputs.

Thanks,

Steve

Originally Posted by dhouston

http://ww1.microchip.com/downloads/e...doc/40040b.pdf

And with one output to spare.

Hi Dave,

I figure (?) you're talking about tip 2 I/O multiplexing ? That may just work for my application. I'll take a close look at it now, it however means redesigning my PCB and changing the code.

And wouldn't it leave 2 outputs to spare, GPIO.4 and .5 ?

Thanks,

SS

EDIT: or was it tip 3 ?

**mackrackit** · - 13th September 2009, 03:50

Here is another option.
http://www.picbasic.co.uk/forum/showthread.php?t=10200
But it would be a complete redesign.

**Sam** · - 13th September 2009, 04:24

Originally Posted by mackrackit

Here is another option.
http://www.picbasic.co.uk/forum/showthread.php?t=10200
But it would be a complete redesign.

Well that's very impressive that your 7 year old did some of the the work and the code ! And it's a very nice project, but it's not practical for my project as it must be on a 1" diameter single sided PCB.

Thanks for the link anyway, it looks like the multiplexing will have to be the way to go for me.

SS

**dhouston** · - 13th September 2009, 13:33

Originally Posted by Sam

I figure (?) you're talking about tip 2 I/O multiplexing ? That may just work for my application. I'll take a close look at it now, it however means redesigning my PCB and changing the code.

And wouldn't it leave 2 outputs to spare, GPIO.4 and .5 ?

Yes, I meant Tip 2. It was past my bedtime - I meant to say it would leave an input pn free plus two input/output pins.

**Sam** · - 13th September 2009, 18:14

Hey Dave,

Thank you very much, that multiplexing completely solved my issue ! I never thought about doing it like that but once you see it (tip 2) it makes perfect sense. It's just what I needed and it's working great.

You're a great asset to the forum and I really appreciate all your help,

SS

**dhouston** · - 13th September 2009, 18:37

I'm surprised I remembered it. I had a copy of that PDF on a network HDD which failed a few weeks back but vaguely recalled it had several unconventional but simple methods for getting the most out of minimal hardware. I have a new, bigger NAS drive but had not grabbed a copy of the PDF until your post jogged my synapses.

The Atmel AVR ATTiny12 allows you to use MCLR as an open drain output but its pinout is different.

**falingtrea** · - 14th September 2009, 18:38

I think that is officially called "Charlieplexing" and is a method originally though up by someone from Maxim Semi. Check this webpage:

http://en.wikipedia.org/wiki/Charlieplexing