Solution: ADC and DAC in a Microcontroller System

ADC: Analog-to-Digital Converter

An ADC converts an analog voltage into a digital code that a microcontroller can process.

Working

Analog Sensor → Signal Conditioning → ADC → Digital Code → CPU

1. The analog signal is applied to the ADC input.
2. The ADC samples the signal.
3. The input range is divided into discrete levels.
4. The nearest digital code is generated.
5. The microcontroller reads the code and converts it into engineering units.

For an ideal $n$-bit ADC with input range $V_{FS}$:

$$LSB = \frac{V_{FS}}{2^n}$$

Approximately, the ADC code is:

$$Code \approx \frac{V_{in}}{V_{FS}}(2^n-1)$$

Example

For a 10-bit ADC with 0–5 V input:

$$LSB \approx \frac{5}{1024}=4.883\text{ mV}$$

DAC: Digital-to-Analog Converter

A DAC converts a digital number generated by the microcontroller into an analog voltage or current.

CPU → Digital Code → DAC → Analog Voltage → Actuator

For an ideal $n$-bit voltage DAC with reference $V_{ref}$:

$$V_{out}\approx\frac{Code}{2^n-1}V_{ref}$$

The exact transfer equation depends on the DAC architecture and datasheet conventions.

Applications

• ADC: temperature, pressure, light and biomedical sensors.
• DAC: waveform generation, motor control references, audio and analog actuator control.

ADC vs DAC

Feature	ADC	DAC
Conversion	Analog → Digital	Digital → Analog
Input	Voltage/current	Digital code
Output	Digital code	Analog voltage/current
Use	Measurement	Control/output generation

Conclusion

ADC enables the microcontroller to measure the physical world, while DAC enables it to generate controlled analog outputs.