AK5371A Datasheet, PDF (26/32 Pages) Asahi Kasei Microsystems – 2ch A/D Converter with USB I/F

ASAHI KASEI
[AK5371A]
5 Device specific Requests
AKM USB Microphone supports ONLY SET_CUR as bRequest field in Set Request Values.
5.1 Audio Control Request
AKM USB microphone support ONLY Feature Unit Control Request, not support other requests. Addition to this,
it only supports SET_CUR value as bRequest field in Set Feature Unit Control Request Values. All Audio Control
Requests are applied to channel 0,1,2, which means master , left and right channel.
5.1.1 Set Feature Unit Control Request
AKM USB Microphone supports only one form of parameter block. Mute control is applied to master channel
(channel 0)
a) Mute Control
Offset Field
Size Value
Description
0
bmRequestType 1 0x21
1
bRequest
1 0x01
SET_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 parameter block of mute control is the following.
Offset Field
Size Value
Description
0
bMute
1 0x01
TRUE
0x00
FALSE
a) Volume Control
Left (channel 1) volume and right (channel 2) volume are controlled independently.
Offset Field
Size Value
Description
0
bmRequestType 1 0x21
1
bRequest
1 0x01
SET_CUR
2
wValue
2 0x0201
VOLUME_CONTROL | CHANNEL_1
0x0202
VOLUME_CONTROL | CHANNEL_2
4
wIndex
2 0x0300
Upper Byte : bUnit ID field in Feature Unit
Descriptor.(0x03)
Lower Byte : Audio Control Interface(0x00)
6
wLength
2 0x0002
Volume Control
The parameter block of mute control is the following.
Offset Field
Size Value
Description
0
wVolume
2 0xZZZZ
The value is mapped to the volume register value.
(refer to Table 1 conversion table )
ZZZZ is assigned by the host
If the wVolume exceeds the range, the AK5371A forces the value into the range. Please see the conversion table in
the Get Feature Unit Control Request.
MS0546-E-00
MS0103-E-00
26
2007/02