SPI with external devices (sensors, displays) in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize SPI communication with the correct clock polarity.

Embedded C

SPI_InitTypeDef SPI_Config;
SPI_Config.CLKPolarity = [1];

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ASPI_POLARITY_LOW

BSPI_POLARITY_HIGH

CSPI_MODE_MASTER

DSPI_FIRSTBIT_MSB

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing clock polarity with clock phase.

Using SPI_MODE_MASTER instead of polarity setting.

The clock polarity must be set to SPI_POLARITY_LOW to ensure the clock idles low, which is common for many SPI devices.

2fill in blank

medium

Complete the code to send a byte of data over SPI.

Embedded C

uint8_t data = 0xA5;
SPI_Transmit([1], 1);

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ANULL

B0xA5

C&data

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the data value directly instead of its address.

Passing NULL which causes no data to send.

The SPI transmit function requires a pointer to the data buffer, so &data is correct.

3fill in blank

hard

Fix the error in the SPI receive code to correctly read one byte.

Embedded C

uint8_t received;
SPI_Receive([1], 1);

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ANULL

Breceived

C*received

D&received

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the variable directly instead of its address.

Using NULL which causes no storage location.

The receive function needs a pointer to store the incoming data, so &received is correct.

4fill in blank

hard

Complete the sensor reading loop by filling both blanks to use the sensor address for SPI read and check if the value is above 100.

Embedded C

for (int i = 0; i < sensor_count; i++) {
    uint16_t value = SPI_Read([1]);
    if (value [2] 100) {
        sensor_values[i] = value;
    }
}

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Asensor_addresses[i]

B>

C<

Dsensor_ids[i]

Attempts:

3 left

💡 Hint

Common Mistakes

Using sensor IDs instead of addresses for SPI read.

Using less than instead of greater than in the condition.

The SPI_Read function should use the sensor's address, and the condition checks if the value is greater than 100.

5fill in blank

hard

Fill all three blanks to correctly configure SPI mode, data size, and first bit order.

Embedded C

SPI_Config.Mode = [1];
SPI_Config.DataSize = [2];
SPI_Config.FirstBit = [3];

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ASPI_MODE_MASTER

BSPI_DATASIZE_8BIT

CSPI_FIRSTBIT_MSB

DSPI_MODE_SLAVE

Attempts:

3 left

💡 Hint

Common Mistakes

Setting slave mode when master is needed.

Using wrong data size constant.

Confusing first bit order.

To configure SPI as master with 8-bit data size and most significant bit first, use these constants.