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S3C9228/P9228 SAM88RCRI INSTRUCTION SET
6-21
EI — Enable Interrupts
EI
Operation: SYM (2) ¨ 1
An EI instruction sets bit 2 of the system mode register, SYM.2 to "1". This allows interrupts to be
serviced as they occur. If an interrupt's pending bit was set while interrupt processing was
disabled (by executing a DI instruction), it will be serviced when you execute the EI instruction.
Flags: No flags are affected.
Format:
Bytes Cycles Opcode
(Hex)
opc 1 4 9F
Example: Given: SYM = 00H:
EI
If the SYM register contains the value 00H, that is, if interrupts are currently disabled, the
statement "EI" sets the SYM register to 04H, enabling all interrupts (SYM.2 is the enable bit for
global interrupt processing).