Arduino Mega 2560 multiple slave via SPI

Question

I'm new to Arduino and microcontroller . I want to connect my Arduino Mega to three slaves which Arduino Unos. I know that these slaves will share MISO, MOSI, and SCK lines. However, SS is unique to each slave.

For single slave, the SS is pin 53. So, for three slaves, which other two pins can I use as SS?

Thank you for your help.

Answer 1

Any you like. There's nothing magic about them, as long as you have the main SS pin as an output to ensure the SPI port is in master mode.

Answer 2

You can use any pin for the Slave Select. The SS pin on the Arduino is only used as SS when the arduino is an SPI slave, not (like in your case) when it's the master. The only thing you have to take care of is to not use the SS pin as an Input.

Just make sure the library you are using allows you to specify your own SS output pin.