89C51IC2-CM ATMEL [ATMEL Corporation], 89C51IC2-CM Datasheet - Page 59

• Manufacturer Part Number: 89C51IC2-CM
• Description: 8-bit Flash Microcontroller with 2-wire Interface
• Manufacturer: ATMEL [ATMEL Corporation]

Registers
4301A–8051–01/04
The PCA interrupt vector is located at address 0033H, the SPI interrupt vector is located
at address 0043H, the I2C interrupt vector at 0043H and Keyboard interrupt vector is
located at address 003BH. All other vectors addresses are the same as standard C52
devices.
Table 47. 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
AT89C51IC2
3 (Highest)
0 (Lowest)
1
2
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