Microprocessor vs. Microcontroller
- Microprocessor – requires additional circuitry to function which is connected via the buses.
(Ex: A soundcard connected to the PCI slot must be used to output sound)
- Microcontroller – Basic circuitry is built to the unit itself hence it can function on its own.
(Ex: To output sound, a microcontroller has a DAC is built in.)
Subsystems in a Microcontroller
· The memory unit is necessary for the storage of program instructions and data.
· Memory appears as an array of cells, each holding a bit pattern which defines the program.
0x23 display “a”
- · In order for the CPU to execute the program stored memory it should fetch it.
- · Hence each memory cell should have an address.
- · The address of the cell is generated by a decoding network.
2. ALU & CU
The Arithmetic and Logical Unit is where calculations and logical operations are performed electronically.
The Control Unit regulates and synchronizes operations of the computer. It consists of Programmable Registers and other electronics. The combination of the ALU + the Control Unit is often referred to as the Central Processing Unit (CPU).
3. I/O & Clock generator
· Input / Output Units:
These units provide the interfaces to the outside world. Information enters the computer via the input unit, and results of the calculations are directed to the outside world via the output units.
· Clock Generator:
All operations within the computer are synchronized to one master clock.
• Electronic signals travel through wires, and there are many connections between various components of the computer, particularly between the CPU and the rest.
• To minimize the number of connections, the wires ("data paths") are shared among many devices and signals can propagate between selected devices and then the selection change.