
INSTRUCTION SET
S3C8248/C8245/P8245/C8247/C8249/P8249
6-40
EI
—
Enable Interrupts
EI
Operation:
SYM (0)
←
1
An EI instruction sets bit zero of the system mode register, SYM.0 to "1". This allows interrupts to
be serviced as they occur (assuming they have highest priority). 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 01H, enabling all interrupts. (SYM.0 is the enable bit for
global interrupt processing.)
Summary of Contents for C8245
Page 31: ...ADDRESS SPACES S3C8248 C8245 P8245 C8247 C8249 P8249 2 20 NOTES ...
Page 107: ...INTERRUPT STRUCTURE S3C8248 C8245 P8245 C8247 C8249 P8249 5 18 NOTES ...
Page 195: ...INSTRUCTION SET S3C8248 C8245 P8245 C8247 C8249 P8249 6 88 NOTES ...
Page 221: ...I O PORTS S3C8248 C8245 P8245 C8247 C8249 P8249 9 16 NOTES ...
Page 245: ...16 BIT TIMER 0 1 S3C8248 C8245 P8245 C8247 C8249 P8249 12 10 NOTES ...
Page 249: ...WATCH TIMER S3C8248 C8245 P8245 C8247 C8249 P8249 13 4 NOTES ...
Page 267: ...A D CONVERTER S3C8248 C8245 P8245 C8247 C8249 P8249 15 6 NOTES ...
Page 299: ...S3P8245 P8249 OTP S3C8248 C8245 P8245 C8247 C8249 P8249 21 8 NOTES ...
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