CM118B Datasheet, PDF (10/25 Pages) C-Media Electronics – Highly Integrated & Configurable USB Audio Single Chip

CM118B
Highly Integrated & Configurable USB Audio Single Chip
4. Function Description
4.1 Content Format for EEPROM (93C46)
The CM118B integrates USB transceiver, internal oscillator and regulator so that only several passive
components are necessary for the USB interface connection. Default USB descriptors are embedded in the CM118B;
therefore there is no additional design effort needed for a generic USB operation. For customized product,
customer can attach a SPI interface 93C46 EEPROM to override the embedded VID, PID and initial/max/min volume
settings. The CM118B automatically detects 93C46 existence and performs the overwrite function during power up.
Each address has 2-byte data, prefix `0x` means hex number
Address
(Hex)
0x00
0x01
0x02
0x03
0x04 ~ 0x09
0x0A
0x0B ~ 0x19
0x1A
0x1B ~ 0x29
0x2A
0x2B
0x2C
0x2D
0x2E
0x2F
0x30
0x31
0x32
Description
bit[15:4] Magic Word -- 0x670X where X = bit 4, 3, 2, 1
bit[3] The value within address 0x2A, 0x2B, 0x32 is valid 1: valid 0: invalid
bit[2] reserved, should be 1
bit[1] serial number enable control 1: enable, 0: disable(default)
bit[0] reserved, should be 1
VID 2-byte
PID 2-byte
Serial number 1st byte
Serial number length
(bit15-bit8, first character) (bit7-bit0)
Serial number 12-byte
Product string 1st byte
Product string length
(bit15-bit8, first character) (bit7-bit0) [0x3E->30,0x40->31Char]
Product string 30-byte (default: USB Audio Device)
Manufacturer string 1st byte Manufacturer string length
(bit15-bit8, first character) (bit7-bit0) [0x3E->30,0x40->31Char]
Manufacturer string 30-byte (default: C-Media Electronics Inc.)
bit[15: 9] DAC initial volume (7-bit, default = -10dB)
bit[8: 3] ADC initial volume (6-bit, default = 8dB)
bit[2] DAC EEPROM MAX/MIN volume valid
bit[1] ADC EEPROM MAX/MIN volume valid
bit[0] AA EEPROM MAX/MIN volume valid
bit[15:11] AA initial volume (5-bit, default = -7dB)
bit[10] Reserved, should be 0
bit[9] Boost mode 0: 22dB 1:12dB (default)
bit[8] Reserved, should be 0
bit[7] Total Power Control 1:enable, 0:disable(default)
bit[6] Reserved, should be 0
bit[5] MIC High Pass Filter 1:enable(default), 0:disable
bit[4] MIC PLL Adjust
1:enable, 0:disable(default)
bit[3] MIC BOOST
1:enable (default), 0:disable
bit[2] DAC Output Terminal property 1: Headset, 0: Speaker(default)
bit[1] HID, 1: enable (default), 0: disable
bit[0] Remote wakeup, 1:enable, 0:disable(default)
bit[15:0] DAC Minimum Volume (0xD300, DAC-Min.=-45dB, default=-37dB)
bit[15:0] DAC Maximum Volume (0x0000, DAC-Max.=0dB, default=0dB)
bit[15:0] ADC Minimum Volume(0xEA00, ADC-Min.=-22dB, default=-12dB)
bit[15:0] ADC Maximum Volume(0x1700, ADC-Max.=+23dB, default=+23dB)
bit[15:0] AA Minimum Volume (0xE900, AA-Min.=-23dB, default=-23dB)
bit[15:0] AA Maximum Volume (0x0800,AA-Max.+8dB, default=+8dB)
EE_OPTION2 Register
bit[3] Reserved, should be 0
bit[2] Reserved, should be 0
bit[1] Reserved, should be 1
bit[0] EE_Stereo, 1: stereo ADC for headset topology, 0: mono ADC for headset
Datasheet Revision: 1.00
Page 10 / 25
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