Why do you select SPI_LAST since you transfer again and again 0xAA ?
Anyway you want first to fully understand the SPI protocol before using it on a DUE. jaxcoder.com tutorial provides a relevant information for that. The main point with SPI is that an SPI Master has to send something ( a Dummy if this is not processed by the SPI Slave) to receive something ( a Dummy if this is not processed by the SPI Master), and so on ....
Plus see this thread: