Datasheet

93
A/T89C51AC2
4127H–8051–02/08
Interrupt System
Introduction The controller has a total of 8 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 49. Interrupt Control System
EX0
IEN0.0
00
01
10
11
External
Interrupt 0
INT0#
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
Timer 2
00
01
10
11
ET2
IEN0.5
TxD
RxD
CEX0:5