Samsung 8-Bit CMOS Microcontroller, S3C9228/P9228 user manual Interrupt Processing Control Points

S3C9228/P9228 INTERRUPT STRUCTURE

5 INTERRUPT STRUCTURE

OVERVIEW

The SAM88RCRI interrupt structure has two basic components: a vector, and sources. The number of interrupt sources can be serviced through a interrupt vector which is assigned in ROM address 0000H–0001H.

VECTOR

0000H

0001H

SOURCES

S1

S2

S3

Sn

NOTES:

1.The SAM88RCRI interrupt has only one vector address (0000H-0001H).

2.The number of Sn value is expandable.

Figure 5-1. S3C9-Series Interrupt Type

INTERRUPT PROCESSING CONTROL POINTS

Interrupt processing can be controlled in two ways: globally, or by specific interrupt level and source. The system- level control points in the interrupt structure are therefore:

—Global interrupt enable and disable (by EI and DI instructions)

—Interrupt source enable and disable settings in the corresponding peripheral control register(s)

ENABLE/DISABLE INTERRUPT INSTRUCTIONS (EI, DI)

The system mode register, SYM (DFH), is used to enable and disable interrupt processing.

SYM.3 is the enable and disable bit for global interrupt processing, which you can set by modifying SYM.3. An Enable Interrupt (EI) instruction must be included in the initialization routine that follows a reset operation in order to enable interrupt processing. Although you can manipulate SYM.3 directly to enable and disable interrupts during normal operation, we recommend that you use the EI and DI instructions for this purpose.

5-1