DMA with ADC for continuous sampling in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start ADC conversion with DMA.

Embedded C

HAL_ADC_Start_DMA(&hadc1, [1], 1);

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A*adc_buffer

B(uint32_t*)adc_buffer

Cadc_buffer

D&adc_buffer

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the buffer without casting to pointer type.

Passing the buffer address without proper type casting.

The DMA requires the address of the buffer cast to uint32_t* to store ADC data.

2fill in blank

medium

Complete the code to configure ADC for continuous conversion mode.

Embedded C

hadc1.Init.ContinuousConvMode = [1];

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ADISABLE

BTRUE

CFALSE

DENABLE

Attempts:

3 left

💡 Hint

Common Mistakes

Setting continuous mode to DISABLE causes single conversion only.

Using boolean TRUE/FALSE instead of ENABLE/DISABLE macros.

To enable continuous ADC conversions, set ContinuousConvMode to ENABLE.

3fill in blank

hard

Fix the error in the DMA initialization for circular mode.

Embedded C

hdma_adc1.Init.Mode = [1];

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ADMA_CIRCULAR

BDMA_NORMAL

CDMA_PINGPONG

DDMA_SINGLE

Attempts:

3 left

💡 Hint

Common Mistakes

Using DMA_NORMAL causes DMA to stop after one transfer.

Using unsupported DMA modes like DMA_PINGPONG or DMA_SINGLE.

For continuous ADC sampling, DMA must be in circular mode (DMA_CIRCULAR) to wrap around the buffer.

4fill in blank

hard

Fill both blanks to complete the ADC DMA interrupt handler.

Embedded C

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc) {
    if(hadc->Instance == [1]) {
        process_data([2]);
    }
}

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AADC1

BADC2

Cadc_buffer

Ddma_buffer

Attempts:

3 left

💡 Hint

Common Mistakes

Checking wrong ADC instance in the callback.

Passing wrong buffer variable to the processing function.

The callback checks if the ADC instance is ADC1 and then processes the data stored in adc_buffer.

5fill in blank

hard

Fill all three blanks to define a DMA buffer and start ADC with DMA.

Embedded C

uint16_t [1][[2]];

int main(void) {
    HAL_Init();
    SystemClock_Config();
    MX_DMA_Init();
    MX_ADC1_Init();

    HAL_ADC_Start_DMA(&hadc1, (uint32_t*)[1], [2]);

    while(1) {
        // main loop
    }
}

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Aadc_buffer

B128

C256

Dbuffer

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between buffer name in declaration and DMA start.

Using incorrect buffer size for DMA transfer.

The DMA buffer is declared as adc_buffer with size 256. The ADC is started with DMA using this buffer and size.