Rainbow Electronics T89C51RD2 - Manual (Page 37)

Rev. F - 15 February, 2001 37
T89C51RD2
6.7. Interrupt System
The T89C51RD2 has a total of 7 interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts
(timers 0, 1 and 2), the serial port interrupt and the PCA global interrupt. These interrupts are shown in Figure 16.
Figure 16. Interrupt Control System
Each of the interrupt sources can be individually enabled or disabled by setting or clearing a bit in the Interrupt
Enable register (See Table 18.). This register also contains a global disable bit, which must be cleared to disable
all interrupts at once.
Each interrupt source can also be individually programmed to one out of four priority levels by setting or clearing
a bit in the Interrupt Priority register (See Table 19.) and in the Interrupt Priority High register (See Table 20.).
shows the bit values and priority levels associated with each combination.
The PCA interrupt vector is located at address 0033H. All other vectors addresses are the same as standard C52
devices.
IE1
0
3
High priority
interrupt
Interrupt
polling
sequence, decreasing
from high to low priority
Low priority
interrupt
Global Disable Individual Enable
EXF2
TF2
TI
RI
TF0
INT0
INT1
TF1
IPH, IP
IE0
0
3
0
3
0
3
0
3
0
3
0
3
PCA IT