Toshiba TC9349AFG Manual page 115

Electronic volume control
電子ボリュームコントロール
Y1 Y2 Y4
VR VR VR
φL15(4)
CH1 CH2 MUTE
The electronic volume pins are also used as port 5 and port P4-3 pins.
These pins are switched to electronic volume pins by using the VR CH1 and VR CH2 bits. Set this bit to "1" to use the
pin as an electronic volume pin. The electronic volume has two channels. Channel 1 (VR CH1 bit) and Channel 2 (VR CH2
bit); corresponding to VRout1/VRin1 and VRout2/VRin2 pins respectively, and the channels are individually adjustable.
The electronic volume attenuation is set by the electronic volume data, which has 5 bits. Setting the most significant bit
updates the lower 4 bits of the electronic volume data, meaning the most significant bit must be accessed; even if only the
lower bits are changed.
The volume can be muted only by setting the −∞ dB bit. When this bit is set to −∞ dB, the electronic volume data will be
retained, and the previous attenuation recovered when −∞ dB is released again. Note that the −∞ dB state obtained by setting
all the electronic volume data to "0" is the same operation as the state obtained by the −∞ dB bit setting.
The electronic volume can also be set to −∞ dB, depending on changes in the I/O port input. When there are changes in
the inputs of the I/O port that has been enabled to break and the MUTE bit is set to "1", the volume will be in muted
( −∞ dB) state. This is used for quick muting, for example, when band switching. This setting is enabled be setting the VR
MUTE bit to "1". This is set by the internal MUTE bit, it is also effective to set the MUTE/P9-1 pin as the I/O port.
( → Refer to the sections on MUTE output.)
The electronic volume control port is assigned to data port 5, and is accessed by using the OUT1 instruction with [CN
= 4H] specified in the operand. The electronic volume control port is reset to "0" after a system reset.
Y8
-∞dB
0: Normal operation (Electronic volume data attenuation)
0 通常動作 電子ボリュームデータ減衰量 ：
-∞dBビット
- ∞ dB bit
1: - ∞ dB (Mute)
： 1 -∞dB(ミュート)
Permission of - ∞ dB bit
MUTEビットによる-∞dBビット制御許可
control by the MUTE bit
Electronic volume pin setting
電子ボリューム端子設定
P4-3/
CH1 CH2
VRout1
0 0
1 0
0 1 I/Oポート
I/O port
1 1
115
（
0:禁止
0: prohibition
1:許可
1: Enabled
P5-0/ P5-1/ P5-2/
VRin1 VRcom VRin2
I/Oポート
I/O port
電子ボリューム
Electronic volume
電子ボリューム
Electronic volume
電子ボリューム
Electronic volume
TC9349AFG
）
P5-3/
VRout2
I/Oポート
I/O port
2006-02-24