STA304 STMicroelectronics, STA304 Datasheet - Page 7

• Manufacturer Part Number: STA304
• Description: Audio DSPs Digital Audio Proc
• Manufacturer: STMicroelectronics

Specifications of STA304

• Mounting Style: SMD/SMT
• Package / Case: TQFP-44
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

STA304
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For more details regarding a specific bit please refer to the appropriate paragraph.
In order to be as much compliant to the specification as possible two different mode of operation has been in-
troduced. Using the AC97_FC_Mode configuration bit the interface can be configured in Full-Compliant mode
(default): in this mode the value returned as response to a read operation will be properly masked in order to
set ‘reserved’ bits to 0, as from specification. This operation is performed on all registers included the Standard
or Extended Audio address space. If the Full-Compliant mode is not selected the full 16 bits data from the cor-
responding RAM register will be returned with no further manipulation.
If an odd-addressed register reading operation is performed the following scheme is adopted:
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2.2 Writing AC `97 Registers
When a write operation into one of the available AC`97 registers is performed the entire 16 bits data word is
written into the related RAM register (also reserved bits are passed through). Some bits of some register may
have a corresponding hardware register (Flip-Flop), used to control the internal status of the device: in this case
the value of the FF is also updated every time a write to the related RAM register is performed. The status of
these FF is reverted to their default values after a hardware reset or a software reset (writing to reg. 00h) request
has been issued; as a consequence also the DSP will have to reset the RAM register contents.
Some register may have a different behaviour from the one depicted above. Here is a brief summary of those
registers.
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to a read request the actual value of this signal is returned, not the RAM content. Due to this fact the relative
RAM register content can be incongruous.
Regs. 2Ch, 2Eh and 30h (Audio Sample Rate Control):
These three registers are used to setup the sample rate when the Variable Rate Mode is enabled. In re-
sponse to a read request on one of these registers the actual value returned can be either BB80h or AC44h,
depending on the status of an internal hardware signal; the status of this signal is updated every time a write
operation into one of these register is performed.
Slot 0:
Slot 1 (address): report the odd address
Slot 2 (data):
Regs. 7Ch and 7Eh:
These are the Vendor ID1 and ID2 registers. Any write request to one of these will be ignored.
Regs. 28h:
The ‘Extended Audio ID Register’ is read only. Therefore any write request will be ignored.
Regs. 26h:
When a write request is issued the actual data written into the RAM register is ‘xxxxxxxxxxxx1110’, where
‘x’ stands for the incoming data.
Regs. 2Ah:
When a write request is issued the actual data written into the RAM register is ‘xxxxxx0111xxxxxx’, where
‘x’ stands for the incoming data.
Regs. 32h and 34h:
Any write request into one of these ADC sample rate register will result in the value BB80h written into the
corresponding RAM register.
report valid bit set to 1 for both slot 1 and slot 2
report all 0s