ATmega Analog Comparator: Simple Voltage Comparison Without ADC Conversion
✏️ EXERCISES
• Proximity Sensors with the Analog Comparator: https://drive.google.com/drive/folder...
• Alternative Exercise: Find the Bandgap Reference Voltage: https://drive.google.com/drive/folder...
In this chapter, you'll master the ATmega's Analog Comparator - a powerful yet often overlooked peripheral that lets you compare voltages efficiently. Unlike the ADC, which requires sampling and conversion, the #AnalogComparator provides instant results when you simply need to know if one voltage is higher or lower than another.
You'll learn how to configure the ACSR (Analog Comparator Status Register) including the ACD disable bit, ACBG for connecting the internal #bandgap reference, and how to read results via ACO. We'll explore interrupt generation using ACI and ACIE bits, with flexible triggering options through ACIS1 and ACIS0 for detecting rising edges, falling edges, or any toggle.
A key feature you'll discover is the ACIC bit that connects the comparator output directly to Timer 1's input capture unit - perfect for timestamping when voltages cross thresholds in your #embedded projects. You'll also learn how to leverage all ADC input channels (ADC0-ADC7) with the comparator when the ADC is disabled, giving you up to 10 comparison channels for #microcontroller applications.
Practical examples include building temperature threshold detectors that can wake the MCU from sleep mode, and proximity sensors using infrared LEDs - commonly used in robotics like smart vacuum cleaners for stair detection. Master the DIDR1 register to reduce power consumption by disabling digital input buffers on analog pins.
Whether you're working on #Arduino projects or bare-metal #ATmega programming, understanding the Analog Comparator opens up efficient solutions for threshold detection, event timing, and low-power monitoring applications.
📖 CHAPTERS
0:00 Introduction
0:50 The Analog Comparator
3:07 How to configure the AC?
7:40 The Input Capture Unit
8:31 Connecting the ADMUX to the AC
10:40 Disable the Digital Inputs
11:37 Recap, ADC vs. AC, and What's next?