Labs should be written for STM$32$ Cube IDE. For the STM$32$F$446$xC$/$E ARM Cortex $-$ M$432$b board. On programming language C$.$ Results should be provided like: step $1$a and code below, step $1$b and code below, for all parts and steps. And all explanations should be provided.

Template:

#include

#include

#include

#include $"$stm$32$f$446$zeLib.h$"$

#include $"$stm$32$f$4$xx$.$h$"$

$//$#define STEP$2$

$//$#define STEP$3$b

$//$#define STEP$4\_5$

$/*$test of interrupts with various priority$/$occurrence conditions$*/$

int main$($void$)\{$

lcd.begin$(16,2)$;

lcd.clear$()$;

lcd.print$(($char $*)"$ INTERRUPT $")$;

$//$ global disable interrupts

$//$ init GPIO pins

$//$ Select interrupt source

$//$ unmask interrupt sources

$//$ select the active edge

$//$ Enable interrupt at NVIC level

#ifdef STEP$4\_5$

$//$ set priorities

#endif

$//$ global enable interrupts

#ifdef STEP$2$

$//$ test INT handler & LEDs using software interrupt

#endif

while $(1)\{//$ waiting for interrupt

$\}$

$\}$

$/*$

$**===========================================================================$

$**$

$**$ Interrupt handlers

$**!!$ do not forget to modify startup$\_$stm$32$f$446$xx$.$s file

$**!!$ do not forget to clear interrupt flag

$**===========================================================================$

$*/$

void EXTI$0\_$IRQHandler$($void$)\{$

#ifndef STEP$3$b

$//$ clear the INT flag here

#endif

$//$ your ISR code here

#ifdef STEP$3$b

$//$ clear the INT flag here

#endif

$\}$

void EXTI$1\_$IRQHandler$($void$)\{$

$//$ your code here

$\}$

Part $1$: Using interrupts

Note: Use the default HSI clock for the microcontroller. You are allowed to use the gpio functions available from the stm$32$f$446$zeLib library.

In violation of good programing practices, the ISR deliberately takes a long time to be able to verify the priority and preemption mechanisms.

STEP$1$: Write a code that loops infinitely and:

$1$a Blinks $5$ times LD$1$ with a blink period of $500$ms on port PG$10$ when a falling edge occurs on port PB$0.$ Keep the interrupt priority at its default value.

$1$b Blinks $12$ times LD$2$ with a blink period of $200$ms on port PG$13$ when a falling edge occurs on port PC$1.$ Keep the interrupt priority at its default value

STEP$2$: Add software interrupts to your code to test the interrupts without using the switches before entering the infinite loop

STEP$3$: The interrupt flag can be cleared anywhere in the ISR. What happens for an new interrupt on EXTI$0$ which occurs while ISR$0$ is currently running:

$3$a: if the flag is cleared at the very beginning of the ISR?

$3$b: if the flag is cleared at its very end?

STEP$4$: The interrupts are not simultaneous

$4$a: Set the same priority level to both interrupts. Verify that an interrupt is memorized if it occurs while the other interrupt is being served $($i$.$e$.$ no preemption$).$ How many events can be memorized for a given interrupt vector?

$4$b: Same test but with a lower priority for EXTI$0\_$IRQn. Verify preemtion of EXTI$0\_$IRQHandler.

STEP$5$: The interrupts are simultaneous $($i$.$e$.$ connected to the same switch using the special cable provided$)$

$5$a: Test the behavior with the same priority for both interrupts. Which interrupt is served first and why?

$5$b: Same test but with a lower priority for EXTI$0\_$IRQn. Which interrupt is served first and why?

$5$c: What happens if you press the switch twice during the execution of the ISR? Explain why.

$5$d: Same test as before but pressing the switch $3$ times or more during the execution of the ISR? Explain.