Write an ARM assembly program in the Keil MDK format that controls the brightness of the LED on the demo board. Set initial LED duty cycle to $21\%$ and implement $32$ grades of brightness. Every press of the BTN$0$ button should modify the LED brightness randomly. Use TIMER$0$ for generating PWM and LETIMER for buttons debouncing.

Use software random number generator that generates next random number in the range $[0-31]$ according to the recursive formula

rand $=(($rand $*11045)+123)\%32,$

Before generating the random numbers initialize variable rand with $21.$ Recursive implementation of the random number generator is not required.$$

making it entirely interrupt$-$driven and adding to it the following features:

LED brightness must be randomly modified with $1/4-$second period only when the button BTN$0$ is pressed and must be kept at the last set value upon its release.

When button BTN$0$ is pressed, the LED brightness must be set to a random value every $1/4$ second provided by RTCC$.$ Use the same software $($pseudo$)-$random number generator as in Assignment $4.$ Detection of any button press should start TIMER$0$ for debouncing and detection of any button release should stop it$.$

Implement button debouncing algorithm with $20-$ms debouncing period provided by TIMER$0.$

Use LETIMER for direct control of the LED brightness with PWM and $5-$ms period.

Thus, you will need to implement handlers for $3$ events: button state changes, TIMER$020-$ms events, and RTCC $1/4-$sec event. Each of them must be interrupt$-$based with NVIC, so no polling loops. This way, the main loop in main$()$ should be reduced to

loop wfi b loop