Abstract
- A hardware component inside CPU that generates Clock Signal to control the speed of CPU processing Instruction
Synchronisation
Clock signal is generated at constant interval, this helps to calculate time and synchronize the internal operations
Play a key role in timing-dependent tasks
Functions like
delay()andmillis()are dependent on the clock
Clock Oscillator for Arduino Uno ATmega328p
- True heart of the Arduino Uno. It’s where your Arduino sketches (code) run, and it handles the primary input/output tasks
External Clock Source
- ATmega328p supports an external clock source of 16MHz-20MHz via Pin 9 and Pin 10
- The Ceramic Resonator is the built-in external clock source that runs at 16MHz
Internal Clock Source
- Calibrated Internal RC Oscillator running at 8MHz
- 128kHz Internal Oscillator running at 128kHz
- More details
Clock Oscillator for Arduino Uno ATmega16u2
- Facilitates Serial Communication between Arduino and computer, converts signals between USB (Universal Serial Bus) and TTL (Transistor-Transistor Logic) serial communication protocols
External Clock Source
- The Crystal oscillator is the built-in external clock source that runs at 16MHZ, named indicating 16.000H9H
- Crystal oscillator is more expensive and accurate, Serial Communication needs such accuracy to work, the data will be corrupted if there is a slight mismatch from the agreed Baud Rate
Internal Clock Source
- Calibrated Internal RC Oscillator running at 8MHz
- PLL running at 48MHz
- More details
Clock Signal
- Represented with
CLK - The continuous oscillating square wave that drives the timing of a digital system
- Used to synchronise the Operation of various components within the circuit
Clock Cycle
- Refers to the time interval between two successive rising (or falling) edges of the Clock Signal. The smallest time unit for CPU
Machine Cycle
- The amount of time the CPU takes to perform a Main Memory or IO Device access. One machine cycle consists of several Clock Cycle
Instruction Cycle
- The amount of time the CPU takes to Fetch, Decode and Execute one Instruction. One Instruction cycle consists of several Machine Cycle
Clock Frequency
- Also known as the clock rate
- The total number of Clock Cycle in one second
Example
500 MHzmeans there are clock cycles in 1 second. Each cycle takes which is2ns.
Duty Cycle
- The ratio of time the Clock Signal is in the high state (logical 1) to the total period of the signal