T89C51RD2-SLSCM View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

T89C51RD2-SLSCM

0 to 40MHz Flash Programmable 8-bit Microcontroller

Atmel Corporation 

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 glo-

bal interrupt. These interrupts are shown in Figure 16.

Figure 16. Interrupt Control System

INT0

IE0

TF0

INT1

IE1

TF1

PCA IT

RI

TI

IPH, IP

3

0

3

0

3

0

3

0

3

0

3

0

High priority

interrupt

Interrupt

polling

sequence, decreasing from

high to low priority

TF2

3

EXF2

0

Individual Enable

Global Disable

Low priority

interrupt

Each of the interrupt sources can be individually enabled or disabled by setting or clear-

ing a bit in the Interrupt Enable register (See Table 23.). 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 (See Table 24.) and in the

Interrupt Priority High register (See Table 22). shows the bit values and priority levels

associated with each combination.

Table 22. Priority Level Bit Values

IPH.x

IP.x

0

0

0

1

1

0

1

1

Interrupt Level Priority

0 (Lowest)

1

2

3 (Highest)

38 T89C51RD2

4243G–8051–05/03

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