Bala Chandar wrote:
>
> In my circuit, I am using all the 8 pins of Port B and pin 6 of Port A as
> inputs to detect the closing of 9 PB switches. The PIC used is 16F628 with
> internal RC Oscillator. Port B weak pull-up is enabled and PortA.6 has a
> 4.7K pull-up resistor.
>
> As I am running short of I/O pins, I want to use an IC to reduce the number
> of pins used by the PIC for detecting key pressings. After a  search through
> CMOS data book, I found 74HC147 (10 to 4 Priority Encoder) almost ideal for
> the purpose. With this IC, I will need only 4 pins of the PIC and as many as
> 5 pins will become available.


Why use a chip? I have one circuit running
16 independant dipswitches, a 7 seg display
and 2 input/output pins on a 16F84 which only
has 13 IO pins, no other chips needed. Exactly
how many things do you need to connect??
-Roman

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