AK5371A Datasheet, PDF (27/32 Pages) Asahi Kasei Microsystems – 2ch A/D Converter with USB I/F

ASAHI KASEI
[AK5371A]
5.1.2 Get Feature Unit Control Request
AKM USB Microphone supports only one form of parameter block.
a) Mute Control
Offset Field
Size Value
Description
0
bmRequestType 1 0xA1
1
bRequest
1 0x81
GET_CUR
2
wValue
2 0x0100
MUTE_CONTROL | CHANNEL_0
4
wIndex
2 0x0300
Upper Byte : bUnit ID field in Feature Unit
Descriptor.(0x03)
Lower Byte : Audio Control Interface(0x00)
6
wLength
2 0x0001
The Length of Mute Control Parameter Block
The device outputs the current setting of mute status.
Offset Field
Size Value
Description
0
bMute
1 0x01
TRUE
0x00
FALSE
b) Volume Control
Offset Field
Size
0
bmRequestType 1
1
bRequest
1
2
wValue
2
4
wIndex
2
Value
0xA1
0x81
0x82
0x83
0x84
0x0201
0x0202
0x0300
6
wLength
2 0x0002
Description
GET_CUR
GET_MIN
GET_MAX
GET_RES
VOLUME_CONTROL | CHANNEL_1
VOLUME_CONTROL | CHANNEL_2
Upper Byte : bUnit ID field in Feature Unit
Descriptor.(0x03)
Lower Byte : Audio Control Interface(0x00)
Volume Control
The parameter block of Volume Control is the following.
Offset Field
Size Value
Description
0
wVolume
2 0xZZYY
bRequest = GET_CUR : returns current volume.
YY must be 00h
0xE100
bRequest = GET_MIN : -31dB
0x1800
bRequest = GET_MAX : +24dB
0x0100
bRequest = GET_RES : 1.0dB
Table 1 is the conversion map of USB class and internal volume register.
When host requests the volume value which is larger than the MAX value in the device, the device is set the MAX
value to the volume. When host requests the volume value which is smaller than the MIN value in the device, the
device is set the MIN value to the volume. RES value is 1.0dB.
MS0546-E-00
MS0103-E-00
27
2007/02