CM119B
USB Audio Single Chip
The CM119B regards the first DATA byte as the register address. The second DATA byte is the content that MCU writes
at the register address. If there is the third DATA byte, the CM119B will auto-increment this byte to the next register
address.
The figure below shows an example of two bytes read transfer. Because the CM119B has auto-increment function, the
second DATA byte will be the register data on the next address.
Note: The USB host tries to get new HID data every 2mS. It’s quite slow. If the continuous write transfers are too
close in terms of time, the former transfer may have no effect.
The figure below shows typical transactions between MCU and t h e CM119B. After a START, MCU should send 7-bit
slave address (0111000) first and then the 8th bit denotes a read transfer when it’s high; or a write transfer when it’s
low.
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Revised: Aug. 2013 Copyright© C-Media Electronics Inc.
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