about voltage interpretation

Although ground is considered “0” and 5V is considered “1” these voltages are rarely present in these ideal values. Voltage is constantly fluctuating and the voltage present on a pin cannot possible change from 0V (ground) to 5V instantaneously.
- 0-1V: considered “low” or “0”
- 4-5V: considered “high” or “1” (CMOS 2.3-3.3V)
- (or some other arbitrary value as documented by the manufacturer in the datasheet)

Although ground is considered “0” and 5V is considered “1” these voltages are rarely present in these ideal values. Voltage is constantly fluctuating and the voltage present on a pin cannot possible change from 0V (ground) to 5V instantaneously.