Epson S1C63558 4.12.8 Programming notes, • When writing, • When reading, BZSTP: One-shotbuzzer stop (FF6DH•D2), BZSHT: One-shotbuzzer trigger/status (FF6DH•D1)

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Sound Generator)

SHTPW: One-shot buzzer pulse width setting register (FF6DH•D0)

Selects the output time of the one-shot buzzer.

When "1" is written: 125 msec

When "0" is written: 31.25 msec

Reading: Valid

Writing "1" into SHTPW causes the one-short output time to be set at 125 msec, and writing "0" causes it to be set to 31.25 msec. It does not affect normal buzzer output.

At initial reset, this register is set to "0".

BZSHT: One-shot buzzer trigger/status (FF6DH•D1)

Controls the one-shot buzzer output.

• When writing

When "1" is written: Trigger

When "0" is written: No operation

Writing "1" into BZSHT causes the one-short output circuit to operate and a buzzer signal to be output. This output is automatically turned OFF after the time set by SHTPW has elapsed. The one-shot output is only valid when the normal buzzer output is OFF (BZE = "0") and will be invalid when the normal buzzer output is ON (BZE = "1"). When a re-trigger is assigned during a one-shot output, the one-shot output time set with SHTPW is measured again from that point (time extension).

• When reading

When "1" is read: BUSY

When "0" is read: READY

During reading BZSHT shows the operation status of the one-shot output circuit. During one-shot output, BZSHT becomes "1" and the output goes OFF, it shifts to "0".

At initial reset, this bit is set to "0".

BZSTP: One-shot buzzer stop (FF6DH•D2)

Stops the one-shot buzzer output.

When "1" is written: Stop

When "0" is written: No operation

Reading: Always "0"

Writing "1" into BZSTP permits the one-shot buzzer output to be turned OFF prior to the elapsing of the time set by SHTPW. Writing "0" is invalid and writing "1" is also invalid except during one-shot output. This bit is dedicated for writing, and is always "0" for reading.

4.12.8 Programming notes

(1)Since the BZ and XBZ signals are generated asynchronous to the BZE register, hazards may be pro- duced when the signal goes ON/OFF due to the setting of the BZE register.

(2)The one-shot output is only valid when the normal buzzer output is OFF (BZE = "0") and will be invalid when the normal buzzer output is ON (BZE = "1").

(3)Since the BZ and XBZ signals are the special outputs of the R01 and R00 ports, it is necessary to set the high impedance control registers (R01HIZ, R00HIZ) to "0", the data registers (R01, R00) to "1" and the output selection registers (BZOUT, XBZOUT) to "1" before setting the BZE register to "1".

108 EPSON S1C63558 TECHNICAL MANUAL