[SOLVED]Shift Register

Hello everyone, i come from electricians world. This question may sound stupid for you all, but when i try to start here i need to understand some things. 1st one is to know exactly what things can a shift register do and not do with an arduino in particular, so here is the question.

¿Do communicate in both directions, i mean, is it possible to get more inputs and outputs with a shift register or just only outputs?

Thanks for your time.

is it possible to get more inputs and outputs with a shift register or just only outputs?

You can do both but not with the same chip.

SRs (normally) take 8 inputs and shift them out serially one bit at a time, OR they accept 1 serial input and present the data as 8 outputs.


Rob

It depends on the specific shift registers you select. Most are either serial in/parallel out for providing more digital output pins. Others are parallel in/serial out for providing more digital input pins.

There were older TTL chips avalible that could do both if wired and controlled correctly, but most only held 4 bits per package and not really that easy to work with for arduino projects.

Reading these should sort you out http://arduino.cc/en/Tutorial/ShiftOut

http://arduino.cc/en/Tutorial/ShiftIn

Thanks a lot mates!

There were older TTL chips avalible that could do both if wired and controlled correctly, but most only held 4 bits per package and not really that easy to work with for arduino projects.

The 74HC299 8-bit SR can shift either way and has parallel load and parallel tri-state output, so its pretty flexible. However it doesn't have latches like the 74HC595 (which is only serial->parallel).