Common embedded bugs and fixes in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to correctly initialize the pointer.

Embedded C

int value = 10;
int *ptr = [1];

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A&value

B*value

Cvalue

Dptr

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable name directly instead of its address.

Dereferencing the variable instead of taking its address.

The pointer must be initialized with the address of the variable using the & operator.

2fill in blank

medium

Complete the code to correctly check if a bit is set in a register.

Embedded C

if ((reg & [1]) != 0) {
    // bit is set
}

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A0x01

B1

C0x00

Dreg

Attempts:

3 left

💡 Hint

Common Mistakes

Using the register itself as a mask.

Using zero as a mask which always results false.

Use a mask with the bit set (0x01) to check the first bit in the register.

3fill in blank

hard

Fix the error in the interrupt service routine declaration.

Embedded C

void [1] ISR_Handler(void) {
    // ISR code
}

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Astatic

Binterrupt

Cvoid

D__interrupt

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'interrupt' instead of '__interrupt'.

Omitting the interrupt keyword entirely.

In embedded C, the ISR function must be declared with the __interrupt keyword to be recognized as an interrupt handler.

4fill in blank

hard

Fill both blanks to correctly define a volatile pointer to a hardware register.

Embedded C

volatile [1] *[2] = (volatile [1] *)0x40021000;

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Auint32_t

Breg

Cint

Dptr

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' instead of 'uint32_t' which may have wrong size.

Using non-volatile types which can cause optimization issues.

The hardware register is usually accessed as a volatile uint32_t pointer. The pointer variable can be named 'ptr'.

5fill in blank

hard

Fill all three blanks to correctly implement a delay loop using a volatile counter.

Embedded C

void delay(void) {
    volatile int [1] = [2];
    while ([1] > 0) {
        [1]--;
    }
}

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Acounter

B10000

Ci

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-volatile variable which the compiler may optimize away.

Initializing the counter to zero which causes no delay.

The volatile variable 'counter' is initialized to 10000 and decremented until zero to create a delay.