Third SPI?

04 Oct 2012


I'm trying to connect three SPI devices at once on the same MBED and I was wondering if this is possible?

Thanks, James

04 Oct 2012

Yes this is fine, just use different chip select lines for each device.

04 Oct 2012


There are two SPI interfaces on the mbed but you can connect multiple devices to each one. For example you could connect three SPI devices as shown below.


Pins 5,6 & 7 are the one of the mbed's SPI interfaces and are shared with all 3 devices. Each SPI device has it's own CS (chip select) line (8, 9 & 10) which you would set low to select the device. You can see an example of a single SPI device being selected and deselected on the SPI handbook page.

You might also choose to connect one of your SPI devices to one SPI interface and 2 to the other.