Sensor reading through ADC (temperature, light) in Embedded C - Step-by-Step Execution

Concept Flow - Sensor reading through ADC (temperature, light)

Start

↓

Initialize ADC

↓

Select Sensor Channel

↓

Start ADC Conversion

↓

Wait for Conversion Complete

↓

Read ADC Value

↓

Convert ADC Value to Physical Unit

↓

Use or Display Sensor Data

↓

End or Repeat

This flow shows how a microcontroller reads sensor data by initializing ADC, selecting the sensor channel, converting analog signals to digital, and then using the converted value.

Execution Sample

Embedded C

void readSensors() {
  ADC_Init();
  ADC_SelectChannel(TEMP_SENSOR_CHANNEL);
  ADC_StartConversion();
  while(!ADC_ConversionComplete());
  int tempValue = ADC_Read();
  float temperature = convertToTemperature(tempValue);
}

This code reads temperature sensor data by starting ADC conversion and converting the raw ADC value to temperature.

Execution Table

Step	Action	ADC State	ADC Value	Temperature Value	Notes
1	ADC_Init()	ADC ready	-	-	ADC hardware initialized
2	ADC_SelectChannel(TEMP_SENSOR_CHANNEL)	Channel set to TEMP_SENSOR_CHANNEL	-	-	Sensor channel selected
3	ADC_StartConversion()	Conversion started	-	-	ADC begins analog to digital conversion
4	while(!ADC_ConversionComplete())	Waiting	-	-	Loop waits until conversion done
5	ADC_ConversionComplete() returns true	Conversion complete	-	-	Conversion finished
6	ADC_Read()	Idle	512	-	Raw ADC value read (example: 512)
7	convertToTemperature(512)	Idle	512	25.0	Raw value converted to 25.0°C
8	Use temperature value	Idle	512	25.0	Temperature can be displayed or used
9	End or repeat	Idle	512	25.0	Process ends or loops for next reading

💡 Process ends after reading and converting sensor data

Variable Tracker

Variable	Start	After Step 6	After Step 7	Final
ADC State	Not initialized	Idle	Idle	Idle
ADC Value	-	512	512	512
Temperature Value	-	-	25.0	25.0

Key Moments - 3 Insights

Why do we wait in a loop after starting ADC conversion?

Because ADC conversion takes time, the loop waits until ADC_ConversionComplete() returns true, ensuring the ADC value is ready before reading (see execution_table step 4 and 5).

What does the raw ADC value represent?

The raw ADC value is a number proportional to the sensor's analog voltage, which must be converted to a meaningful unit like temperature (see execution_table step 6 and 7).

Why do we select a sensor channel before starting conversion?

Because ADC can read multiple sensors, selecting the channel tells ADC which sensor's signal to convert (see execution_table step 2).

Visual Quiz - 3 Questions

Look at the execution table, what is the ADC Value read at step 6?

A 25.0

B 512

C 0

D -1

💡 Hint

Check the 'ADC Value' column at step 6 in the execution_table.

At which step does the ADC conversion complete?

A Step 3

B Step 4

C Step 5

D Step 6

💡 Hint

Look for when ADC_ConversionComplete() returns true in the execution_table.

If the ADC value was 1023 instead of 512, what would change in the variable_tracker?

A Temperature Value would be higher than 25.0

B ADC State would change to 'Busy'

C ADC Value would stay 512

D Temperature Value would be lower than 25.0

💡 Hint

Higher ADC raw value means higher sensor reading, check 'Temperature Value' in variable_tracker.

Concept Snapshot

Sensor reading via ADC:
1. Initialize ADC hardware.
2. Select sensor channel.
3. Start ADC conversion.
4. Wait until conversion completes.
5. Read raw ADC value.
6. Convert raw value to physical unit (e.g., °C).
7. Use or display the sensor data.

Full Transcript

This visual execution trace shows how a microcontroller reads sensor data using ADC. First, the ADC hardware is initialized. Then, the sensor channel is selected to tell the ADC which sensor to read. The ADC conversion starts, and the program waits in a loop until the conversion is complete. After completion, the raw ADC value is read. This raw value is a number representing the sensor's analog voltage. It is then converted to a physical unit like temperature in degrees Celsius. Finally, the converted sensor data can be used or displayed. Variables like ADC state, ADC value, and temperature value change step-by-step as shown in the tables. Key moments clarify why waiting is needed, what the raw ADC value means, and why channel selection is important. The quiz questions help check understanding of these steps.