MISO - Alternate Use

I'm working on controlling three SPI devices from the same Duemilanove.

Since the Arduino is the Master at all times, can I use the Master_In_Slave_Out (Pin 12) as a secondary Slave Select?

Thanks, I've been trying to google this and keep getting ridiculous feedback.

I believe the SPI hardware configures it as an input automatically so it won't be usable as an output - but I could be wrong and it can be overridden with pinMode() - try it and see for a definitive answer! (Reading the datasheet might produce an answer too, but it might be easier to try it).

Alternatively software bit-banged SPI would do the job.

Aw nip this is gonna create some big issues haha.

Well, I guess I'm going to edit SPI.h and remove whatever sets that pin to an input since it never gets used....and then hope for the best.

Isn't the SPI a hardware function?
See Section 18 of the data sheet:
"When the SPI is enabled, the data direction of the MOSI, MISO, SCK, and SS pins is overridden
according to Table 18-1 on page 168."

just because the 'duino is a master doesn't mean that MISO is unused
you typically send a command on MOSI and read the reply/data on MISO

not "typically" - that is how the hardware is built in the ATMega.
So you enable SPI by writing the SPI enable register, and the configuration of the pins is determined from there.

I meant "typically" in terms of the use of MISO and MOSI
I accept that the hardware also uses them that way
I suspect that the OP isn't aware that even the master has to listen sometimes :slight_smile: