Matrix Keypad routine

[Darrel Taylor]

I think that's for a standard 10 TTL loads.

But a PIC pin is only 1 load. So you can be fine with 40K, which is somewhere around the range of the internal weak pull-ups.
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[RussMartin]

I think that's for a standard 10 TTL loads.

But a PIC pin is only 1 load. So you can be fine with 40K, which is somewhere around the range of the internal weak pull-ups.
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I'm sure you're correct, Darrel. As I wrote, that was a long time ago. My feeble point was, I still automatically use that thumb rule and those values and the circuits still work. (Probably kind of like driving a tack with a sledgehammer . . . )

[Darrel Taylor]

Or shooting Quail with a Deer slug.

But keep in mind we're talking keypads here.
For something like high speed communication with I2C, lower values are required to overcome any capacitance that might cause a Slew Rate.

In which case 4.7K is the perfect value.

I'd say, just keep doing what you're doing, and you should be fine.
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