Specifications

S1C62N82 TECHNICAL SOFTWARE EPSON II-83

CHAPTER 3: PERIPHERAL CIRCUITS (Interrupt and Halt)

Set the EI state at the start of the interrupt processing

routine to allow nesting of the interrupts. Then the priority

of the interrupt or the nesting level is determined and set by

hardware.

The interrupt factor flags must always be reset before set-

ting the EI status in the corresponding interrupt processing

routine. (The flag is reset when the interrupt condition flag

is read by software.)

If the EI instruction is executed without resetting the inter-

rupt factor flag after generating the timer interrupt or the

stopwatch timer interrupt or melody, and if the correspond-

ing interrupt mask register is still "1", the same interrupt is

generated once more. (See Figure 3.12.6.)

If the EI state is set without resetting the interrupt condition

flag after generating the input interrupt (K00–K03, K10), the

same interrupt is generated once more. (See Figure 3.12.6.)

Reading of interrupt factor flags is available at EI, but be

careful in the following cases.

If the interrupt mask register value corresponding to the

interrupt factor flags to be read is set to 1, an interrupt

request will be generated by the interrupt factor flags set

timing, or an interrupt request will not be generated.

Be very careful when interrupt factor flags are in the same

address.

The timer interrupt factor flags (IT32, IT8, IT2) and the

stopwatch interrupt factor flags (ISW1, ISW0) are set

whether the corresponding interrupt mask register is set or

not.

The input interrupt factor flags (IK0, IK1) are allowed to be

set in the condition when the corresponding interrupt mask

enabled). (See Figure 3.12.6.)