Chapter 2: Circuit and System Operation

MCS51 System Circuit

• Pin configuration– Power– Ground– System Clock (18, 19 Crystal pin)

• Operation Sample Add A, R1• Machine Cycle is package of clock signal

– Reset– External Access (/EA)

• Port• Schematic• Machine Cycle

Pin 40: Power SupplyHandout Chapter 2

Pin 20: GroundHandout Chapter 2

Pin 18, 19: CrystalHandout Chapter 2

Pin 31: External AccessHandout Chapter 2

Pin 9: ResetHandout Chapter 2

Port

• 32 I/O Lines• Bidirectional Property• Bit-Addressable port Property• Pulled-up Resister pin (Port 1, 2 and 3)• Open collector pin

Port 0

• Handout Chapter 2

Port 1

• Handout Chapter 2

Port 2

• Handout Chapter 2

Port 3

• Handout Chapter 2

Basic Output Device

• LED

https://en.wikipedia.org/wiki/Light-emitting_diode

Basic Input Device

• Switch

http://www.digibay.in/158-momentary-tactile-dip-push-button-switch

MCS51 System Circuit

Homework 1• Draw schematic of MCS51 System circuit with following specification.

– Reset Switch– Connect with 8 Display LEDs– Connect with 4 Push button switchesCheck list: Identify Component ID for every devices in the diagram (such as U1, SW1,

SW2, LED1, LED2) Identify all used Pin Number Identify all used Pin Name Specify Component's value Specify Voltage of Power Supply

Note: Submit Homework BEFORE the next class start.