Circular buffer DMA mode in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the size of the circular buffer.

Embedded C

volatile uint8_t dma_buffer[[1]];

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A256

B512

C1024

D128

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a size that is not a power of two.

Using a size too large for the memory.

The circular buffer size is set to 256 bytes to match the DMA transfer size.

2fill in blank

medium

Complete the code to enable circular mode in the DMA configuration.

Embedded C

DMA_InitStructure.DMA_Mode = [1];

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ADMA_Mode_MemoryToMemory

BDMA_Mode_PeripheralControl

CDMA_Mode_Normal

DDMA_Mode_Circular

Attempts:

3 left

💡 Hint

Common Mistakes

Using normal mode which stops after one transfer.

Choosing memory-to-memory mode which is not suitable here.

DMA_Mode_Circular enables the circular buffer mode for continuous data transfer.

3fill in blank

hard

Fix the error in the DMA interrupt flag clearing code.

Embedded C

DMA_ClearFlag(DMA1_Stream5, [1]);

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ADMA_FLAG_FEIF5

BDMA_FLAG_TEIF5

CDMA_FLAG_TCIF5

DDMA_FLAG_HTIF5

Attempts:

3 left

💡 Hint

Common Mistakes

Clearing the half-transfer flag instead of transfer complete.

Clearing error flags which do not acknowledge normal completion.

The transfer complete flag (DMA_FLAG_TCIF5) must be cleared to acknowledge the DMA transfer completion.

4fill in blank

hard

Fill both blanks to correctly configure the DMA buffer size and enable the DMA stream.

Embedded C

DMA_InitStructure.DMA_BufferSize = [1];
DMA_Cmd(DMA1_Stream5, [2]);

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A256

BENABLE

CDISABLE

D128

Attempts:

3 left

💡 Hint

Common Mistakes

Using a buffer size that does not match the array.

Disabling the DMA stream by mistake.

The buffer size must match the circular buffer size (256), and the DMA stream must be enabled with ENABLE.

5fill in blank

hard

Fill all three blanks to correctly set the DMA peripheral address, memory address, and data direction.

Embedded C

DMA_InitStructure.DMA_PeripheralBaseAddr = [1];
DMA_InitStructure.DMA_Memory0BaseAddr = [2];
DMA_InitStructure.DMA_DIR = [3];

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A(uint32_t)&USART1->DR

B(uint32_t)dma_buffer

CDMA_DIR_PeripheralToMemory

DDMA_DIR_MemoryToPeripheral

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping peripheral and memory addresses.

Setting direction incorrectly as memory to peripheral.

The peripheral base address is the USART data register, the memory base address is the dma_buffer, and the direction is from peripheral to memory for receiving data.