INTERRUPT STRUCTURE

S3C84E5/C84E9/P84E9

 

 

SYSTEM MODE REGISTER (SYM)

The system mode register, SYM (set 1, DEH), is used to globally enable and disable interrupt processing (see Figure 5-5).

A reset clears SYM.0 to "0".

The instructions EI and DI enable and disable global interrupt processing, respectively, by modifying the bit 0 value of the SYM register. In order to enable interrupt processing an Enable Interrupt (EI) instruction must be included in the initialization routine, which follows a reset operation. Although you can manipulate SYM.0 directly to enable and disable interrupts during the normal operation, it is recommended to use the EI and DI instructions for this purpose.

System Mode Register (SYM)

DEH, Set 1, R/W

MSB

.7

 

.6

.5

 

 

 

.4

.3

 

.2

 

.1

.0

LSB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Not used for the

 

S3C84E5/C84E9/

 

 

 

 

 

 

 

Global interrupt enable bit:

 

 

 

 

 

 

 

 

 

 

 

P84E9

 

 

 

 

 

 

 

 

 

 

 

 

 

0 = Disable all interrupts processing

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 = Enable all interrupts processing

 

 

 

 

 

 

 

 

Fast interrupt level

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

selection bits:

 

 

 

 

Fast interrupt enable bit:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 = Disable fast interrupts processing

 

 

 

 

 

 

 

0

 

0

0

IRQ0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 = Enable fast interrupts processing

 

 

 

 

 

 

 

0

 

0

1

IRQ1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

1

0

IRQ2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

1

1

IRQ3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

0

0

IRQ4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

0

1

IRQ5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

1

0

IRQ6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

1

1

IRQ7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 5-5. System Mode Register (SYM)

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Samsung S3C84E5 user manual System Mode Register SYM, IRQ0, IRQ1 IRQ2 IRQ3 IRQ4 IRQ5 IRQ6 IRQ7