CM108 Datasheet, PDF (20/29 Pages) C-Media Electronics – USB Audio I/O Controller

CM108
Integration Dual DAC, Earphone Driver, ADC,
Microphone Booster, PLL, Regulator, and USB Transceiver
7.4 Internal Registers
All internal registers of CM108 can be accessed via generic HID functional calls without
the need to develop kernel mode driver. Totally 4 bytes of data can be read or write from HID.
Input report is for read and output report is for write. Internal registers of CM108 are used to
control GPIO, S/PDIF output, and EEPROM data access.
HID_IR0 (HID input report byte 0)
Offset : 0x00
Bits Read/Write
Description
Default
7-6
R
00: HID_IR1 is used as GPI
0x0
10: Values written to HID_IR0-3 are also
mapped to EEPROM_DATA0-1,
EEPROM_CTRL
Others: Reserved
5-4
R
Reserved
0x0
3
R
0: No activity on Record-Mute button
0x0
1: Record-Mute button pressed then released
2
R
0: No activity on Playback-Mute button
0x0
1: Playback-Mute button pressed then
released
1
R
0: Volume-Down button released
0x0
1: Volume-Down button pressed
0
R
0: Volume-Up button released
0x0
1: Volume-Up button pressed
HID_IR1 (HID input report byte 1)
Offset : 0x01
Bits Read/Write
Description
7-0
R
When HID_IR0[7:6] == 2’b00:
HID_IR1[3:0] is the input from GPIO4 ~
GPIO1 in input mode
When HID_OR0[7] == 1’b1:
Mapped from EEPROM_DATA0
Default
0x00
Date: Nov/01/2004
- 19 -
Version: 1.5