Bose Companion 5 Service Manual page 44

USB Controller
DSP
USB Controller
Memory and I2C interface
The TAS1020 contains an internal ROM and all Data and Program RAM. An external EEROM, U6002, stores the
portion of the program code custom to the Companion 5 application. Once the TAS1020 has come out of reset,
it will read the code stored in U6002 via the Inter Integrated Circuit (I2C) communications path on pins 43 and
44. This buss is also used for transferring non-audio information between the USB controller and the DSP. The
TAS1020 is permanent master on this buss and provides the clock and command/address portions of all
instructions. The DSP always behaves as the slave device on this interface.
Booting, EEROM
The logic state of pins U7000.[108,110,111] are selected to permit booting from the external EEROM, U7001,
using the I2C protocol. The proper state of pins 108 and 111 depend on the I2C pins of U6000 being idle when
DSPRESET\ is released. The DSP will take approximately 2.8 seconds to read the EEROM contents and
complete internal initialization. In order to assure that the I2C state machine internal to the EEROM, U7001, is
in a known state, the components C7100, Q7100, and R7100 are used to momentarily remove the +3.3V
power from the EEROM each time the USB controller places the DSP into reset.
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