Two devices using SPI Communications pins on UNO 10, 11, 12, 13 ?

Projects General Guidance
1

I was wanting to do a project using an Arduino Uno R3, an Ethernet shield and a RFID reader but the Ethernet shield and the RFID both show that they use pins 10, 11, 12, and 13 for SPI communications to the UNO. Is there a way that I can redirect the RFID to use a different set of pins or can I only use one of these devices.

Any Ideas?
Thanks Steve

2

You need three shared pins (CLK, MISO, MOSI) plus one SS (slave select) for each device on an SPI bus.
To communicate with a device set the appropriate SS to HIGH and the others LOW.p

3

+1 to wvmarle.

Steve, SPI is a bus that can take many 'passengers'. The select lines determine which talk at any time.

You might find the Wikipedia article very interesting.

4

GoForSmoke:
+1 to wvmarle.

Steve, SPI is a bus that can take many 'passengers'. The select lines determine which talk at any time.

You might find the Wikipedia article very interesting.
Serial Peripheral Interface - Wikipedia

This makes sense in my little brain. Newbie here.

Thanks
Steve

5

You could actually clock SPI inputs in (you have none now) as you clock outputs out, sort of doubles the speed. : o )

Note that if you turn on all of a 595's pins the output will be like 6 or 8mA each? But that should be enough for the ULN2803.

I can't deal with your wiring and sketch but I wonder if you ever had a point where it was 1 shift reg and 1 2803 driving 1 motor working?