MCLR OFF is it Good or Bad!

[Suraj143]

In 628A I always leave RA5 (MCLR) free.In config I always put MCLR = OFF.So every time I don't need to add a pull up resister.

Is this good?

 

[mvs sarma]

In 628A I always leave RA5 (MCLR) free.In config I always put MCLR = OFF.So every time I don't need to add a pull up resister.

Is this good?

if you keep mclr off and suppose you want to use internal clock, the programming mode becomes an issue and your programmer should have Vpp before Vdd facility.

 

[Suraj143]

Hello mvs sarma Thanks

Forget the programing mode, In working mode is it ok by leaving the MCLR pin by turning off MCLR?

 

[mvs sarma]

Hello mvs sarma Thanks

Forget the programing mode, In working mode is it ok by leaving the MCLR pin by turning off MCLR?

it would use internal pull up and the pin is spared. perhaps youcan also use it as input pin

 

[Odin]

In 628A I always leave RA5 (MCLR) free.In config I always put MCLR = OFF.So every time I don't need to add a pull up resister.

Is this good?

In theory, yes. I've used it a bit. But it's been giving me some trouble with the communication from a ICD-clone. It became unstable, and I spend hours figuring out what was wrong. So for me it's no more MCLR as input. Your milage may vary.

 

[arhi]

I found it good practice to have a reset switch on the board so whenever possible I use MCLR=on and pull up with external resistor + reset sw to gnd ... I only disable MCLR when I really need the extra pin. The pull up resistor do not take too much space on the board nor add some significant value to the price... If you are not going to use mclr as input, use it for reset.

If you decide to turn off mclr and use it as input pin, make sure that
- you have programmer with vpp before vdd option (any ICD like pickit2, junebug will work)
- you properly isolate the ICSP connector from the rest of the circuit