CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Input Ports)

SIK00–SIK03: K0 port interrupt selection register (FF20H)SIK10–SIK13: K1 port interrupt selection register (FF24H)

Selects the ports to be used for the K00–K03 and K10–K13 input interrupts.

When "1" is written: Enable

When "0" is written: Disable

Reading: Valid

Enables the interrupt for the input ports (K00–K03, K10–K13) for which "1" has been written into the interrupt selection registers (SIK00–SIK03, SIK10–SIK13). The input port set for "0" does not affect the interrupt generation condition.

At initial reset, these registers are set to "0".

KCP00–KCP03: K0 port input comparison register (FF22H)KCP10–KCP13: K1 port input comparison register (FF26H)

Interrupt conditions for terminals K00–K03 and K10–K13 can be set with these registers.

When "1" is written: Falling edge

When "0" is written: Rising edge

Reading: Valid

The interrupt conditions can be set for the rising or falling edge of input for each of the eight bits (K00– K03 and K10–K13), through the input comparison registers (KCP00–KCP03 and KCP10–KCP13).

For KCP00–KCP03, a comparison is done only with the ports that are enabled by the interrupt among K00–K03 by means of the SIK00–SIK03 registers. For KCP10–KCP13, a comparison is done only with the ports that are enabled by the interrupt among K10–K13 by means of the SIK10–SIK13 registers.

At initial reset, these registers are set to "0".

EIK0: K0 input interrupt mask register (FFE4H•D0)EIK1: K1 input interrupt mask register (FFE5H•D0)

Masking the interrupt of the input port can be selected with these registers.

When "1" is written: Enable

When "0" is written: Mask

Reading: Valid

With these registers, masking of the input port interrupt can be selected for each of the two systems (K00– K03, K10–K13).

At initial reset, these registers are set to "0".

IK0: K0 input interrupt factor flag (FFF4H•D0)IK1: K1 input interrupt factor flag (FFF5H•D0)

These flags indicate the occurrence of input interrupt.

When "1" is read: Interrupt has occurred

When "0" is read: Interrupt has not occurred

When "1" is written: Flag is reset

When "0" is written: Invalid

The interrupt factor flags IK0 and IK1 are associated with K00–K03 and K10–K13, respectively. From the status of these flags, the software can decide whether an input interrupt has occurred.

The interrupt factor flag is set to "1" when the interrupt condition is established regardless of the interrupt mask register setting. However, the interrupt does not occur to the CPU when the interrupt is masked. These flags are reset to "0" by writing "1" to them.

After an interrupt occurs, the same interrupt will occur again if the interrupt enabled state (I flag = "1") is set or the RETI instruction is executed unless the interrupt factor flag is reset. Therefore, be sure to reset (write "1" to) the interrupt factor flag in the interrupt service routine before shifting to the interrupt enabled state.

At initial reset, these flags are set to "0".

S1C63558 TECHNICAL MANUAL

EPSON

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