Reading analog sensors through ADC in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the library needed to read from the ADC.

Raspberry Pi

import [1]

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Aspidev

Btime

Cmath

Drandom

Attempts:

3 left

💡 Hint

Common Mistakes

Importing unrelated libraries like random or math.

Forgetting to import the SPI library.

The spidev library is used to communicate with SPI devices like the MCP3008 ADC chip.

2fill in blank

medium

Complete the code to open SPI bus 0, device 0 for communication.

Raspberry Pi

spi = spidev.SpiDev()
spi.[1](0, 0)

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Aopen

Bconnect

Cstart

Dinit

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods like start or connect which do not exist.

Forgetting to open the SPI device before use.

The open method opens the SPI bus and device for communication.

3fill in blank

hard

Fix the error in the function that reads data from channel 0 of the MCP3008 ADC.

Raspberry Pi

def read_adc(channel):
    adc = spi.xfer2([1, (8 + [1]) << 4, 0])
    data = ((adc[1] & 3) << 8) + adc[2]
    return data

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A1

B0

Cspi

Dchannel

Attempts:

3 left

💡 Hint

Common Mistakes

Hardcoding the channel number instead of using the parameter.

Using an undefined variable.

The function must use the channel parameter to select the ADC channel dynamically.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that reads ADC values for channels 0 to 3.

Raspberry Pi

adc_values = {ch: read_adc(ch) for ch in [1] if ch [2] 3}

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Arange(4)

Brange(3)

C<=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using range(3) which excludes channel 3.

Using < which excludes channel 3.

range(4) generates 0,1,2,3 and <= includes channel 3 in the dictionary.

5fill in blank

hard

Fill all three blanks to convert the raw ADC value to voltage assuming a 3.3V reference and 10-bit ADC.

Raspberry Pi

voltage = ([1] / [2]) * [3]

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Araw_value

B1023

C3.3

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1024 instead of 1023 as max ADC value.

Multiplying before dividing.

Using wrong reference voltage.

The formula converts the raw ADC reading to voltage: raw_value divided by max ADC value (1023) times reference voltage (3.3V).