Roman Black wrote:

> Hi Bala, I didn't claim to do anything magic,
> just that it worked without needing another
> chip. :o)
>
> What you require above is an interesting
> challenge. You have 27 separate signals that
> you want to connect to 16 pins? Wow.
> You already have a few chips in the circuit,
> in your case it may be more work trying to
> do it without extra chip. More work than
> it's worth? :o)

Hi Roman,

I forgot to mention that the circuit (with all the PB switches, relays,
DS1820, LEDs, etc.) in the breadboard stage is working satisfactorily. As
you have mentioned, there are already extra chips (5841 & 74HC595) to
provide additional outputs.

Since I wanted to add a couple of features, I was looking for ways of
getting extra I/O pins.

I like the suggestion by Tim McDonough of using 4021 that will give 8
inputs. (74HC165 can also be used, I think, as it looks a functional
equivalent of 4021.) Since I already have two pins working as common Clock
and Data outputs, I can use them for 4021 as Clock and Load outputs. This
means, by using only one pin to receive the serial data, I can get 8
additional inputs.

Thanks for your '16 PB switches + diodes + 7Seg Disp' circuit you have put
up in your site. It will be very useful in a different project of mine.

Regards,
Bala

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