AT89C51RB2-RLTCM ATMEL [ATMEL Corporation], AT89C51RB2-RLTCM Datasheet - Page 53

• Manufacturer Part Number: AT89C51RB2-RLTCM
• Description: 8-bit Microcontroller with 16K/ 32K Bytes Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Interrupt System
Figure 21. Interrupt Control System
4180B–8051–04/03
EXF2
KBD IT
SPI IT
INT0
INT1
PCA IT
TF0
TF1
TF2
RI
TI
Individual Enable
The AT89C51RB2/RC2 has a total of 9 interrupt vectors: two external interrupts (INT0
and INT1), three timer interrupts (timers 0, 1 and 2), the serial port interrupt, SPI inter-
rupt, Keyboard interrupt and the PCA global interrupt. These interrupts are shown in
Figure 21.
Each of the interrupt sources can be individually enabled or disabled by setting or clear-
ing a bit in the Interrupt Enable register (Table 45 and Table 47). 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 lev-
els by setting or clearing a bit in the Interrupt Priority register (Table 48) and in the
Interrupt Priority High register (Table 46 and Table 47) shows the bit values and priority
levels associated with each combination.
IE0
IE1
IPH, IPL
Global Disable
3
0
3
0
3
0
3
0
3
0
3
0
3
0
3
0
3
0
AT89C51RB2/RC2
High Priority
Interrupt
Interrupt
Polling
Sequence, Decreasing From
High to Low Priority
Low Priority
Interrupt
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