Clock gating for power saving in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable clock gating for the peripheral.

Embedded C

CLK_CTRL_REG |= [1];  // Enable clock gating

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ACLK_GATE_DISABLE

BCLK_GATE_ENABLE

CCLK_ALWAYS_ON

DCLK_RESET

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing the disable or reset option instead of enable.

Setting CLK_GATE_ENABLE enables clock gating, which saves power by stopping the clock to unused peripherals.

2fill in blank

medium

Complete the code to disable clock gating for the peripheral.

Embedded C

CLK_CTRL_REG &= ~[1];  // Disable clock gating

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ACLK_GATE_ENABLE_BIT

BCLK_GATE_ENABLE

CCLK_GATE_ENABLE_MASK

DCLK_GATE_DISABLE

Attempts:

3 left

💡 Hint

Common Mistakes

Using the enable constant instead of the bit mask.

Using CLK_GATE_ENABLE_BIT with bitwise NOT disables the clock gating by clearing the bit.

3fill in blank

hard

Fix the error in the clock gating control code.

Embedded C

if ((CLK_CTRL_REG & [1]) == 0) {
    enable_clock_gating();
}

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ACLK_GATE_DISABLE_BIT

BCLK_GATE_RESET_BIT

CCLK_GATE_STATUS_BIT

DCLK_GATE_ENABLE_BIT

Attempts:

3 left

💡 Hint

Common Mistakes

Checking the disable or reset bit instead of the enable bit.

The code checks if the clock gating enable bit is cleared (0) to enable clock gating. So it must check CLK_GATE_ENABLE_BIT.

4fill in blank

hard

Fill both blanks to create a clock gating control macro.

Embedded C

#define SET_CLOCK_GATING(reg, bit) \
    do { \
        (reg) [1]= (bit); \
    } while(0)

#define CLEAR_CLOCK_GATING(reg, bit) \
    do { \
        (reg) [2]= (bit); \
    } while(0)

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A|

B&

C~

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using AND to set bits or OR to clear bits.

To set a bit, use bitwise OR |=. To clear a bit, use bitwise AND with the bitwise NOT &= ~. Here, CLEAR_CLOCK_GATING uses &= and expects the bit to be complemented before passing.

5fill in blank

hard

Fill all three blanks to implement a function that gates clock based on enable flag.

Embedded C

void clock_gate_control(volatile uint32_t *reg, uint32_t bit, bool enable) {
    if (enable) {
        *reg [1]= bit;  // Enable clock gating
    } else {
        *reg [2]= [3] bit;  // Disable clock gating
    }
}

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

A|=

B&=

C~

D^=

Attempts:

3 left

💡 Hint

Common Mistakes

Using XOR or other operators incorrectly for bit setting/clearing.

To enable clock gating, set the bit with OR assignment |=. To disable, clear the bit by AND assignment &= with the complement ~ of the bit.