8255 alternative which has small footprint

[terry]

Hi,

I need to multiplex data bus to two devices to save pins. I only know
8255 can do that. Is there another alternative which can do the same
job but has smaller number of pins?

Thanks!

 

[raven imap]

Hi,

I need to multiplex data bus to two devices to save pins. I only know
8255 can do that. Is there another alternative which can do the same
job but has smaller number of pins?

Too many unknowns, what are you trying to muliplex,how many pins, how fast ?

Steve

 

[Nicholas O. Lindan]

I need to multiplex data bus to two devices to save pins. I only know
8255 can do that. Is there another alternative which can do the same
job but has smaller number of pins?

The 74xx373 / 74xx374 was the old solution.

Maxim/Dallas/AD(?) make a serial to parallel I/O expander. Esp.
useful if the I/O is distributed, as in a machine or large
scientific instrument.

Or, as the chorus says, use a PIC.

 

[Leon Heller]

Hi,

I need to multiplex data bus to two devices to save pins. I only know
8255 can do that. Is there another alternative which can do the same
job but has smaller number of pins?

You could use a CPLD - a few more pins but it would be a *lot* smaller.

Leon

 

[Ken Smith]

You could use a CPLD - a few more pins but it would be a *lot* smaller.

The ICT 7540 could be made to take in nibbles and latch out bytes. It
only needs 24 pins.

 

[Rich Grise]

Hi,

I need to multiplex data bus to two devices to save pins. I only know 8255
can do that. Is there another alternative which can do the same job but
has smaller number of pins?

We need more information here, because typically the devices themselves
do the "multiplexing" by chip select lines.

If you just want to shuttle data back and forth, a couple of 74HC245s
would do it, albeit that's still 40 pins.

Good Luck!
Rich