AT89C55WD_02 Datasheet, PDF (18/37 Pages) ATMEL Corporation – 8-bit Microcontroller with 20K Bytes Flash

Table 7. Interrupt Enable (IE) Register
(MSB)
EA
–
ET2
ES
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables the interrupt.
(LSB)
ET1
EX1
ET0
EX0
Symbol
Position
Function
EA
IE.7
Disables all interrupts. If EA = 0, no interrupt is acknowledged. If EA
= 1, each interrupt source is individually enabled or disabled by
setting or clearing its enable bit.
–
IE.6
Reserved.
ET2
IE.5
Timer 2 interrupt enable bit.
ES
IE.4
Serial Port interrupt enable bit.
ET1
IE.3
Timer 1 interrupt enable bit.
EX1
IE.2
External interrupt 1 enable bit.
ET0
IE.1
Timer 0 interrupt enable bit.
EX0
IE.0
External interrupt 0 enable bit.
User software should never write 1s to reserved bits, because they may be used in future AT89
products.
Figure 10. Interrupt Sources
0
INT0
IE0
1
TF0
0
INT1
IE1
1
TF1
TI
RI
TF2
EXF2
18 AT89C55WD
1921B–MICRO–09/02