Epson S1C63558 R00–R03:R0 output port data register (FF31H), R10–R13:R1 output port data register (FF33H), R20–R23:R2 output port data register (FF35H)

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Output Ports)

R00HIZ–R03HIZ: R0 port high impedance control register (FF30H)R10HIZ–R13HIZ: R1 port high impedance control register (FF32H)R20HIZ–R23HIZ: R2 port high impedance control register (FF34H)

Controls high impedance output of the output port.

When "1" is written: High impedance

When "0" is written: Data output

Reading: Valid

By writing "0" to the high impedance control register, the corresponding output terminal outputs according to the data register. When "1" is written, it shifts into high impedance status.

When an output port (R00–R03, R10–R13) is used for special output, fix the corresponding high impedance control register at "0" (data output).

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

R00–R03: R0 output port data register (FF31H)R10–R13: R1 output port data register (FF33H)R20–R23: R2 output port data register (FF35H)

Set the output data for the output ports.

When "1" is written: High level output

When "0" is written: Low level output

Reading: Valid

The output port terminals output the data written in the corresponding data registers without changing it. When "1" is written to the register, the output port terminal goes high (VDD), and when "0" is written, the output port terminal goes low (VSS).

When an output port (R00–R03, R10–R13) is used for special output, fix the corresponding data register at "1".

At initial reset, these registers are all set to "1".

XBZOUT: R00 output selection register (FF65H•D0)

Selects the R00 terminal function.

When "1" is written: XBZ output

When "0" is written: General-purpose DC output

Reading: Valid

When using the R00 terminal for the XBZ output, write "1" to this register. Furthermore, fix the R00 register at "1" and the R00HIZ register at "0". Refer to Section 4.12, "Sound Generator", for controlling the XBZ output.

When using the R00 output port for a general-purpose output, fix this register at "0". At initial reset, this register is set to "0".

BZOUT: R01 output selection register (FF65H•D1)

Selects the R01 terminal function.

When "1" is written: BZ output

When "0" is written: General-purpose DC output

Reading: Valid

When using the R01 terminal for the BZ output, write "1" to this register. Furthermore, fix the R01 register at "1" and the R01HIZ register at "0". Refer to Section 4.12, "Sound Generator", for controlling the BZ output.

When using the R01 output port for a general-purpose output, fix this register at "0". At initial reset, this register is set to "0".

38 EPSON S1C63558 TECHNICAL MANUAL