MCLR pin make it output low?

nailuy · Joined: 21 Sep 2010 Posts: 166

Hy.
I'm not sure I can make a pin that only has construction MCLR input an to output? just to make it a logical zero.
I know on this pin must be 9-12V on programming and can't be output as logical HI, by construction.
I want to use in future project this pin for output...
thank you

temtronic · Posted: Sat Jan 24, 2026 2:03 pm

my gut says no but... please post which PIC you're using . There's a LOT of new PICs, some may do what you want.
I've stayed with 40 pinners for the past 3+ decades,have never run out of pins. close though, had a porject with just ONE extra pin !

nailuy · Joined: 21 Sep 2010 Posts: 166

I'm beginner...
I don't have a project now
I talk wit my friends at table and begin to wonder if I can use this pin for output as low.
cpu must be like SO16 (low spaces) an use all pins for output MCLR as low output.

temtronic · Posted: Sat Jan 24, 2026 3:43 pm

again, post a PIC and I'll look at the datasheet

SO16 is a 16 pin device, -2 for power, gives 14 for I/O. I don't know of any PICs like that. You also have to consider that 2 other pins are used for ICSP so they MUST have 'special' wiring/parts to be used for BOTH programming and I/O. I suggest using a 28 pin device as the MINUMUM.

Smaller is NOT better.
By using a bigger PIC, you'll probably not run out of code space, I/O pins or functions. Also as you use ONE PIC, you'll create a common 'library' of functions like LCD, ADC,SIO, etc. that you know work, makes new projects quicker to code !

I use DIPs for everything...easy to prototype and troubleshoot. I can get nice protoboards for 40 pin PICs for $2 each CDN, lots of room for extra parts.

nailuy · Joined: 21 Sep 2010 Posts: 166

thank you.
when i decide to make this project I will back wit news now is only ieea /teory.
best regards
Smile

temtronic · Posted: Sun Jan 25, 2026 6:49 am

OK, I got curious, looked at 6 or 7 '14 pin' PICs and NONE of them allow the I/O pin with MCLR to be an output.
I still recommend using an 18 or 28 pin PIC for your projects.

Ttelmah · Joined: 11 Mar 2010 Posts: 20031

i don't think any PIC allows MCLR to be an output. The reason is that MCLR
has other special functions (programming), so has to be able to be pulled
high for this. So does not have an output driver, since if it did this would
be reverse biased during programming. Result smoke.....