Multiple SPI devices and not enough pins

ErikdS

Hello,
for the project I'm working on I need more pins than the BS has, so I thought of hooking up all SPI slaves on common CS and CLK lines, and accessing one dataline at the time so the master can read from each slave in turn.
This is not daisy-chaining clearly, and I cannot that, as most devices I work <with don't support that.
So the question is simple: can it be done?
Kind regards
Erik

Mike G

Don't tie the chip select (CS) pins together. The chip select pin selects a chip for communication. Tie the slave device's MOSI, MISO, and CLK together.
http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

A master SPI device will needs it's own IO.

Chris Savage

The following project demonstrates how to connect six (6) SPI type devies to the BS2 sharing the clock and data lines and only using separate chip select lines. There were still I/O pins left over for a rotary encoder, serial LCD and speaker and I think I even had a few unused. Hopefully this will help.

http://www.savagecircuits.com/forums/content.php?333-Binary-Digital-Clock