Voltage Levels - What Are High and Low?
đĄ What Are Voltage Levels?â
Voltage levels are the "language" of digital circuits. Just like we use words to communicate, computers and microcontrollers use voltage to represent 0 and 1.
đ¤ High vs Low Voltageâ
Think of it like a light switch:
- Low (or 0) = switch off
- High (or 1) = switch on
In the digital world, voltage tells the circuit whether something is "on" or "off".
Voltage levels define the thresholds for logical 0 and logical 1. Any voltage above a certain threshold is interpreted as logic HIGH (1), and any voltage below a lower threshold is interpreted as logic LOW (0). This is the foundation of all digital logic.
⥠Voltage Levels in Common Power Suppliesâ
5V Systems (like classic Arduino)â
| Logical State | Typical Voltage |
|---|---|
| Low (0) | 0V - 1.5V |
| High (1) | 3.5V - 5V |
| Perfect High | 5V |
3.3V Systems (like modern microcontrollers)â
| Logical State | Typical Voltage |
|---|---|
| Low (0) | 0V - 1.0V |
| High (1) | 2.0V - 3.3V |
| Perfect High | 3.3V |
â What About the Voltage in Between?â
If you have a voltage that's not clearly high or low (like 2.5V in a 5V system), the microcontroller might get confused! It could interpret it as 0 or 1 randomly. That's why we always try to use clean, clear voltages for digital signals.
đ Why Do We Need This?â
- Consistent Communication - All components agree on what "on" and "off" mean
- Noise Resistance - Small voltage variations won't confuse the circuit
- Interoperability - Different components can work together if they use the same voltage levels
đ Classroom Exampleâ
Show students:
- Connect an LED to a microcontroller pin
- When you set the pin HIGH (5V or 3.3V), the LED lights up
- When you set the pin LOW (0V), the LED turns off
This is the simplest demonstration of digital logic!
đĄ Summaryâ
- Low (0) = near 0V
- High (1) = near power supply voltage (5V or 3.3V)
- Always use clean voltage levels for reliable operation
- Different systems use different voltage thresholds - check your hardware!