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S3C9454B/F9454B
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.)
Summary of Contents for S3C9454B
Page 1: ...S3C9454B F9454B 8 BIT CMOS MICROCONTROLLER USER S MANUAL Revision 1 ...
Page 25: ...PRODUCT OVERVIEW S3C9454B F9454B 1 10 NOTES ...
Page 35: ...ADDRESS SPACES S3C9454B F9454B 2 10 NOTES ...
Page 65: ...CONTROL REGISTERS S3C9454B F9454B 4 18 NOTES ...
Page 123: ...CLOCK CIRCUIT S3C9454B F9454B 7 4 NOTES ...
Page 133: ...RESET and POWER DOWN S39454B F9454B 8 10 NOTES ...
Page 145: ...I O PORTS S3C9454B F9454B 9 12 NOTES ...
Page 173: ...A D CONVERTER S3C9454B F9454B 12 8 NOTES ...
Page 183: ...ELECTRICAL DATA S3C9454B F9454B 13 10 NOTES ...