Datasheet

113
AT89C51AC3
4383D–8051–02/08
Interrupt System
Introduction The Micro-controller has a total of 9 interrupt vectors: two external interrupts (INT0 and
INT1), three timer interrupts (timers 0, 1 and 2), a serial port interrupt, a PCA, a timer
overrun interrupt and an ADC. These interrupts are shown below.
Figure 63. Interrupt Control System
EX0
IEN0.0
00
01
10
11
External
Interrupt 0
INT0#
EA
IEN0.7
EX1
IEN0.2
External
Interrupt 1
INT1#
ET0
IEN0.1
Timer 0
EC
IEN0.6
PCA
ET1
IEN0.3
Timer 1
ES
IEN0.4
UART
EADC
IEN1.1
A to D
Converter
Interrupt Enable
Lowest Priority Interrupts
Highest
Priority Enable
00
01
10
11
00
01
10
11
00
01
10
11
00
01
10
11
00
01
10
11
00
01
10
11
Priority
Interrupts
AIN1:0
IPH/L
Timer 2
00
01
10
11
ET2
IEN0.5
TxD
RxD
CEX0:5
00
01
10
11
ESPI
IEN1.3
SPI
Controller