SPI data transfer sequence in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start the SPI data transfer by enabling the SPI peripheral.

Embedded C

SPI->[1] |= SPI_CR1_SPE;

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ACR1

BDR

CSR

DCR2

Attempts:

3 left

💡 Hint

Common Mistakes

Using data register (DR) instead of control register.

Trying to enable SPI in status register (SR).

The SPI control register 1 (CR1) contains the SPE bit which enables the SPI peripheral.

2fill in blank

medium

Complete the code to wait until the SPI transmit buffer is empty before sending data.

Embedded C

while (!(SPI->SR & [1]));

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ASPI_SR_TXE

BSPI_SR_BSY

CSPI_SR_OVR

DSPI_SR_RXNE

Attempts:

3 left

💡 Hint

Common Mistakes

Waiting for RXNE (receive buffer not empty) instead of TXE.

Checking BSY flag incorrectly.

The TXE (Transmit buffer empty) flag in the status register (SR) indicates when the transmit buffer is ready for new data.

3fill in blank

hard

Fix the error in the code that writes data to the SPI data register.

Embedded C

SPI->[1] = data;

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ASR

BCR2

CCR1

DDR

Attempts:

3 left

💡 Hint

Common Mistakes

Writing data to control or status registers instead of data register.

The data register (DR) is used to write data to be transmitted via SPI.

4fill in blank

hard

Fill both blanks to check if SPI is busy and wait until it is free before disabling it.

Embedded C

while (SPI->SR & [1]) {} 
SPI->[2] &= ~SPI_CR1_SPE;

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ASPI_SR_BSY

BSPI_SR_TXE

CCR1

DDR

Attempts:

3 left

💡 Hint

Common Mistakes

Checking wrong flags or disabling SPI in wrong register.

The BSY flag in the status register (SR) shows if SPI is busy. The SPI is disabled by clearing SPE bit in CR1.

5fill in blank

hard

Fill all three blanks to create a function that sends a byte over SPI and waits for completion.

Embedded C

void SPI_SendByte(uint8_t data) {
    while (!(SPI->SR & [1]));
    SPI->[2] = data;
    while (SPI->SR & [3]) {}
}

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ASPI_SR_TXE

BDR

CSPI_SR_BSY

DCR1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong flags or registers in the function.

This function waits for the transmit buffer to be empty (TXE), writes data to the data register (DR), then waits until SPI is not busy (BSY) before returning.