at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 111

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

Registers
94
AT89C51RE2
Table 74. Priority Level Bit Values
A low-priority interrupt can be interrupted by a high priority interrupt, but not by another
low-priority interrupt. A high-priority interrupt can’t be interrupted by any other interrupt
source.
If two interrupt requests of different priority levels are received simultaneously, the
request of higher priority level is serviced. If interrupt requests of the same priority level
are received simultaneously, an internal polling sequence determines which request is
serviced. Thus within each priority level there is a second priority structure determined
by the polling sequence.
IPH. x
0
0
1
1
IPL. x
0
1
0
1
Interrupt Level Priority
3 (Highest)
0 (Lowest)
1
2
7663B–8051–03/07