Hello, I have an Ardunio Uno and and attempting to interface two other devices through SPI. I am already using a CAM 204 chip through SPI successfully, and am trying to add BLE functionality with the BLE Nano.
My question is, Is multiple SPI connections possible with the Arduino?
If not, should I switch to adding a shield such as the BLE shield, or an entirely new microcontroller such as the nRF51822? each of which seem to run Arduino written programs
Yes, multiple SPI is possible. That's why SPI is very useful.
Each SPI device needs to use one of the Arduino's outputs as a "chip select" (CS) so it knows when it should listen to the SPI data wires. The default CS is pin 10 but you can use any other pin - usually select one of the digital pins 2-9. The Arduino code needs to set the CS pin for the device it wants to talk to before starting the SPI data and then un-set it when it's finished with that device.
The reason why pin 10 is special is that's used if you are trying to make the Arduino into a slave (listener) on an SPI bus. When the Arduino is a master, then any pin is OK.
The analog pins can also be used, they are digital pins 14-19 (A0 to A5).
D10 must be an output, even if not being used for CS during an SPI transfer - otherwise, if it's an Input and it goes low, the SPI port becomes a slave vs master as MorganS indicated, and only the SPI master creates the SCK clock for transfers.