CM6308 C-Media Electronics, Inc., CM6308 Datasheet - Page 25

• Manufacturer Part Number: CM6308
• Description: Cm6308 Usb Audio Chip Specification
• Manufacturer: C-Media Electronics, Inc.

CM6308
Single-Chip USB Solution for
Audio and Voice Applications
It is important to notice that the contents of this register, after a write transaction completes,
have no meaning. However, after a read transaction completes, you should reference the
codec’s documentation to see how many bits in this register are valid. For example, if the codec
is Analog Device AD1837, then SPI_Data_Reg[9:0] will be valid data.
As the highest SPI clock frequencies are different for many codecs, two control bits are used to
adjust the spi_clk frequency to gain the maximum transfer speed. The CM6308 can control up
to six codecs through the SPI interface, as shown in Fig. F below.
Fig. F. The SPI connection topology
7.2.2
2-bit leading mode
2-bit leading mode is designated for LCM controllers. Its waveform is almost the same as the
general SPI except for two extra bits, RW and RS, in the beginning of each transaction. See the
following figure.
Date: 09/04/2007
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