$/**$ EX: $9\mathrm{.}2$

$$ Create two new files:

$$ src$/$spi$.$c

$$ include$/$spi$.$h

$$ TASK:

$1.$ In "spi.c$",$ declare and implement a function "spi$\_$init" that will

$$initialise SPI$0$ in unbuffered mode, such that data can be written

$$to the shift register that controls the $7-$segment display.

$$This function should also enable the SPI interrupt via the IE bit

$$in INTCTRL.

$2.$ Declare and implement the function spi$\_$write$($uint$8\_$t b$)$ which

$$will write the byte b out via the SPI interface.

$3.$ Declare and implement an ISR that handles the SPI interrupt, and

$$also creates a rising edge on the DISP LATCH net.

$$You will need to add some code to spi$\_$init$()$ to enable the

$$required pins as outputs.

$$ Declare prototypes for these functions in "spi.h$"$ and include

$$ "spi.h$"$ at the top of this file.

$$ Once this exercise is complete, uncomment the lines below. The

$7-$segment display should be blank after this code executes.

$*/$

$/**$ CODE: Write your code for Ex $9\mathrm{.}2$ in spi.c and spi.h$.*/$