Rainbow Electronics AT89C55WD - Manual (Page 18)

18
AT89C55WD
1921B–MICRO–09/02
Figure 10. Interrupt Sources
Table 7. Interrupt Enable (IE) Register
(MSB) (LSB)
EA – ET2 ES ET1 EX1 ET0 EX0
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables the interrupt.
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.
IE1
IE0
1
1
0
0
TF1
TF0
INT1
INT0
TI
RI
TF2
EXF2