CM108 Datasheet, PDF (14/29 Pages) C-Media Electronics – USB Audio I/O Controller

CM108
Integration Dual DAC, Earphone Driver, ADC,
Microphone Booster, PLL, Regulator, and USB Transceiver
7. FUNCTION DESCRIPTIONS
7.1 USB Interface
CM108 integrates USB transceiver, PLL, and regulator. So only a few passive
components are necessary for the USB interface connection. Default USB descriptors are
embedded in CM108; therefore no additional design effort is needed for USB operation. PID
will be changed with the MODE pin setting, so different setting will have different PID. For
customized product, customer can attach a 93C46 EEPROM to override the embedded VID,
PID and provide addition serial number for each set. CM108 will automatically detect the
93C46 existence and performs the overwrite function during power up.
7.1.1 Device Descriptor
Offset
Field
Size
0
bLength
1
1
bDescriptorType
1
2
bcdUSB
2
4
bDeviceClass
1
5 bDeviceSubClass 1
6
bDeviceProtocol
1
7 bMaxPacketSize0 1
8
idVendor
2
10
idProduct
2
12
bcdDevice
2
14
iManufacturer
1
15
iProduct
1
16
iSerialNumber
1
17 bNumConfigurations 1
Value
(Hex)
Description
12 _{Total 18 Bytes}
01 _{Device Descriptor}
0110 _{USB 1.1 compliant.}
00
00
00
40 _{Endpoint zero Size = 64 bytes}
0d8c _{Vendor ID}
0008 ~ _{Product ID}
000F _{Programmable by MSEL and MODE pin}
0100 _{Device compliant to the Audio Device}
Class specification version 1.00
01 _{Index of string descriptor describing}
manufacturer
02 _{Index of string descriptor describing}
product
03 _{Index of string descriptor describing the}
device’s serial number
01 _{Configurations number = 1}
Note: VID, PID, and serial number can be overridden by external EEPROM content
Date: Nov/01/2004
- 13 -
Version: 1.5