AT89C51ID2-SLSIM Atmel, AT89C51ID2-SLSIM Datasheet - Page 64

• Manufacturer Part Number: AT89C51ID2-SLSIM
• Description: C51ID2 64KF TWI 32KHZ PLCC44 3-5.5V IND.
• Manufacturer: Atmel

Registers
64
AT89C51ID2
The PCA interrupt vector is located at address 0033H, the SPI interrupt vector is located
at address 0043H and Keyboard interrupt vector is located at address 004BH. All other
vectors addresses are the same as standard C52 devices.
Table 48. 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
4289C–8051–11/05