Key points of 89C51 microcontroller interrupt knowledge-EEWORLD

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(The picture shows the 89C51 pin diagram)

1. There are 5 interrupt sources in the 89C51 microcontroller: two external interrupts, two timer/counter interrupts (overflow), and one serial port interrupt.

2. There are two different types of interrupts in the microcontroller interrupt system: one is called non-maskable interrupt, which cannot be disabled by the user through software; the other is called masked interrupt, which is the type described in this article.

2. Control words

1. External interrupt. Pins 12 and 13 (P3.2, P3.3) of the microcontroller are introduced and named INT0 and INT1. The above TCON register is used to control external interrupts.

IT0: Trigger mode of INT0. 0 means low level trigger; 1 means negative transition trigger.

IE0: This bit is set to 1 when an external interrupt enters. Automatically cleared to 0 after CPU responds.

2. Internal interrupt. TCON register, described in Timer.

3. The serial port is interrupted.

4. Interrupt enable register

Interrupt enable register
EA	X	ET2	ES	ET1	EX1	ET0	EX0

EA: master switch

ET2: Timer/counter 2 control bit, supported by 89C52.

Others: timer/counter 0, 1 and external interrupt 0, 1 control bits.

5. Interrupt entry address

² External interrupt 0 (INT0): 0003H

² Timer 0 (T0): 000BH

² External interrupt 1 (INT1): 0013H

² Timer 1 (T1): 001BH

² Serial port interrupt: 0023H

Keywords：89C51 Reference address：Key points of 89C51 microcontroller interrupt knowledge

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