Single channel ADC reading in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start the ADC conversion.

Embedded C

ADC_Start([1]);

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AADC1

BADC2

CADC3

DADC4

Attempts:

3 left

💡 Hint

Common Mistakes

Using an uninitialized ADC channel.

Passing an incorrect channel name.

The function ADC_Start is called with the ADC channel to begin conversion. Here, ADC1 is the correct channel.

2fill in blank

medium

Complete the code to check if the ADC conversion is complete.

Embedded C

if (ADC_GetFlagStatus([1]) == SET) { /* conversion done */ }

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AADC_FLAG_AWD

BADC_FLAG_OVR

CADC_FLAG_STRT

DADC_FLAG_EOC

Attempts:

3 left

💡 Hint

Common Mistakes

Checking the wrong flag like overrun or start flags.

Confusing flag names.

The flag ADC_FLAG_EOC (End Of Conversion) indicates the ADC has finished converting.

3fill in blank

hard

Fix the error in reading the ADC value.

Embedded C

uint16_t adcValue = [1]();

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AADC_ReadValue

BADC_GetValue

CADC_GetConversionValue

DADC_Read

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent or incorrect function name.

Confusing reading and starting functions.

The correct function to get the converted ADC value is ADC_GetConversionValue().

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps channel numbers to their ADC values if the value is above 1000.

Embedded C

adc_results = { [1]: [2] for [1] in channels if [2] > 1000 }

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Ach

Badc_value

Cvalue

Dchannel

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable name for both blanks.

Using undefined variable names.

We use ch as the loop variable for channels and adc_value as the value for each channel. The comprehension maps channel to its ADC value if the value is above 1000.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps channel names in uppercase to their ADC values if the value is greater than 2000.

Embedded C

adc_data = { [1].[2](): [3] for [1] in channels if [3] > 2000 }

Drag options to blanks, or click blank then click option'

Ach

Bupper

Cadc_val

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect method names.

Mixing variable names.

The loop variable is ch. We call upper() on it to get uppercase channel names. The ADC value is stored in adc_val. The comprehension filters values greater than 2000.

Practice

1. What does a single channel ADC do in embedded C programming?

easy

A. It reads one analog input and converts it to a digital number.

B. It writes digital data to an analog output.

C. It reads multiple analog inputs simultaneously.

D. It converts digital signals to analog signals.

Solution

1. Step 1: Understand ADC function

   An ADC (Analog to Digital Converter) converts analog signals to digital numbers.

2. Step 2: Identify single channel meaning

   Single channel means it reads only one analog input at a time.

3. Final Answer:

   It reads one analog input and converts it to a digital number. -> Option A

4. Quick Check:

   Single channel ADC = One analog input read [OK]

Hint: Single channel ADC reads one input only [OK]

Common Mistakes:

• Confusing ADC with DAC
• Thinking ADC reads multiple inputs at once
• Mixing analog output with input reading

2. Which of the following is the correct way to start an ADC conversion in embedded C?

easy

A. ADC_Stop();

B. ADC_StartConversion();

C. ADC_Read();

D. ADC_Init();

Solution

1. Step 1: Identify function to start ADC

   Starting ADC conversion usually requires a function like ADC_StartConversion().

2. Step 2: Differentiate other functions

   ADC_Read() reads the value, ADC_Init() initializes hardware, ADC_Stop() stops ADC.

3. Final Answer:

   ADC_StartConversion(); -> Option B

4. Quick Check:

   Start ADC = ADC_StartConversion() [OK]

Hint: Start ADC with ADC_StartConversion() [OK]

Common Mistakes:

• Using ADC_Read() to start conversion
• Confusing initialization with start
• Calling ADC_Stop() instead of start

3. What will be the output of this code snippet if the ADC reads a value of 512?

int adcValue = ADC_Read();
printf("ADC Value: %d\n", adcValue);

medium

A. ADC Value: 0

B. ADC Value: 1023

C. ADC Value: 512

D. ADC Value: -512

Solution

1. Step 1: Understand ADC_Read() output

   ADC_Read() returns the current digital value from ADC, here given as 512.

2. Step 2: Print the value

   printf prints the integer value stored in adcValue, which is 512.

3. Final Answer:

   ADC Value: 512 -> Option C

4. Quick Check:

   ADC_Read() = 512 printed as is [OK]

Hint: ADC_Read() returns current ADC number [OK]

Common Mistakes:

• Assuming ADC_Read() returns max value always
• Confusing negative values in ADC reading
• Printing wrong variable or format

4. Identify the error in this ADC reading code:

ADC_Init();
int value = ADC_Read();
ADC_StartConversion();
printf("Value: %d", value);

medium

A. Variable 'value' should be float

B. ADC_Init() is missing

C. printf format specifier is wrong

D. ADC_StartConversion() should be called before ADC_Read()

Solution

1. Step 1: Check ADC function order

   ADC_StartConversion() must be called before ADC_Read() to start conversion.

2. Step 2: Analyze code sequence

   Here, ADC_Read() is called before starting conversion, so it reads old or invalid data.

3. Final Answer:

   ADC_StartConversion() should be called before ADC_Read() -> Option D

4. Quick Check:

   Start conversion before reading ADC [OK]

Hint: Start ADC conversion before reading value [OK]

Common Mistakes:

• Reading ADC before starting conversion
• Ignoring initialization step
• Wrong printf format for int

5. You want to read an analog sensor value using a single channel ADC and convert it to voltage (0-5V) with 10-bit resolution. Which code snippet correctly calculates the voltage?

int adcValue = ADC_Read();
float voltage = ?;

hard

A. voltage = (adcValue / 1023.0) * 5.0;

B. voltage = (adcValue * 5) / 1023;

C. voltage = adcValue * 5.0 / 1024.0;

D. voltage = (adcValue / 1024) * 5;

Solution

1. Step 1: Understand ADC resolution and voltage range

   10-bit ADC means values from 0 to 1023 represent 0 to 5 volts.

2. Step 2: Calculate voltage correctly

   Voltage = (adcValue / 1023.0) * 5.0; uses floating division and full scale 1023.

3. Final Answer:

   voltage = (adcValue / 1023.0) * 5.0; -> Option A

4. Quick Check:

   Voltage = ADC value / max * 5V [OK]

Hint: Divide by 1023.0 for 10-bit ADC voltage calc [OK]

Common Mistakes:

• Dividing by 1024 instead of 1023
• Using integer division instead of float
• Multiplying before dividing causing wrong result