Watching register values in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read the value from the register REG_A.

Embedded C

uint8_t value = [1];

Drag options to blanks, or click blank then click option'

A*REG_A

BREG_A

C&REG_A

DREG_A()

Attempts:

3 left

💡 Hint

Common Mistakes

Using REG_A without dereferencing returns the pointer, not the value.

Using ®_A gives the address of the pointer, not the register value.

To read the value stored at the memory address of REG_A, you need to dereference the pointer using *REG_A.

2fill in blank

medium

Complete the code to write the value 0xFF to the register REG_B.

Embedded C

[1] = 0xFF;

Drag options to blanks, or click blank then click option'

AREG_B

BREG_B()

C&REG_B

D*REG_B

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning to REG_B directly changes the pointer, not the register value.

Using ®_B is the address of the pointer, not the register.

To write a value to the hardware register, you must dereference the pointer REG_B and assign the value.

3fill in blank

hard

Fix the error in the code to toggle bit 3 of the register REG_C.

Embedded C

*REG_C = *REG_C [1] (1 << 3);

Drag options to blanks, or click blank then click option'

A&

B^

C|

D<<

Attempts:

3 left

💡 Hint

Common Mistakes

Using & clears bits instead of toggling.

Using | sets bits but does not toggle.

Using << is a shift operator, not a bitwise toggle.

To toggle a bit, use the XOR operator ^ with a mask that has that bit set.

4fill in blank

hard

Fill both blanks to check if bit 5 of REG_D is set and clear it if true.

Embedded C

if ((*REG_D [1] (1 << 5)) != 0) {
    *REG_D [2]= ~(1 << 5);
}

Drag options to blanks, or click blank then click option'

A&

B|=

C&=

D^=

Attempts:

3 left

💡 Hint

Common Mistakes

Using |= sets bits instead of clearing.

Using ^= toggles bits instead of clearing.

Use & to check if bit 5 is set. Use &= ~ to clear that bit.

5fill in blank

hard

Fill all three blanks to create a mask for bits 0 to 3, set those bits in REG_E, and then read the masked value.

Embedded C

uint8_t mask = (1 [1] 4) - 1;
*REG_E [2]= mask;
uint8_t val = *REG_E [3] mask;

Drag options to blanks, or click blank then click option'

A<<

B|=

C&

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using ^ to set bits toggles them instead.

Using & to set bits clears other bits.

Shift 1 left by 4 to create mask bits 0-3. Use |= to set bits. Use & to read masked bits.