Question about Option_Reg

[aratti]

Only bit 7 of OPTION_REG control the weak pullup on portB and only on portB.

When :

OPTION_REG.7 = 0 the weak pullup are set

OPTION_REG.7 = 1 the weak pullup are removed

Naturally the pullup apply only if portB is an input, otherwise if is set as an OUTPUT, you don't need any pullup.

If you need a pulldown situation, on portB, then you set OPTION_REG.7 = 1 and you connect external resistors from pins to ground.

Al.

[financecatalyst]

Thanks Aratti......But is it a reliable way to do it? On one side it's great that I save space on my PCB. Has any of your projects caused any problems or unreliable operation due to internal PULL up or Pull down?