DATA SHEET
MAS 35x9F
2.3.1. RAM and Registers
selected, the Layer 2, Layer 3 or AAC bit stream is rec-
ognized and decoded automatically.
The DSP core has access to two RAM banks denoted
D0 and D1. All RAM addresses can be accessed in a
20-bit or a 16-bit mode via I C bus. For fast access of
To add/remove MPEG layers while running in MPEG
decoding mode (e.g. Layer 2, Layer 3 (0x0c) to
Layer 2, Layer 3, AAC (0x1c)), the application selec-
tion has to be reset before writing the new value.
2
internal DSP states the processor core has an address
space of 256 data registers which also can be
2
accessed via I C bus. For more details, please refer to
Section 3.3. on page 27.
For general control purposes, the operation system
provides a set of I C instructions that give access to
2
internal DSP registers and memory areas.
2.3.2. Firmware and Software
An auxiliary digital volume control and mixer matrix is
applied to the digital stereo audio data. This matrix is
capable of performing the balance control and a sim-
ple kind of stereo basewidth enhancement. All four
factors LL, LR, RL, and RR are adjustable, please
refer to Fig. 3–3 on page 44.
2.3.2.1. Internal Program ROM and Firmware,
MPEG-Decoding
The firmware implemented in the program ROM of the
MAS 35x9F provides MPEG 1/2 Layer 2, MPEG 1/2/
2.5 Layer 3 and MPEG 2 AAC-decoding as well as a
G.729 encoder and decoder.
2.3.2.2. Program Download Feature
The DSP operating system starts the firmware in the
“Application Selection Mode”. By setting the appropri-
ate bit in the Application Select memory cell (see
Table 3–8 on page 32), the MPEG audio decoder or
the G.729 Codec can be activated.
The standard functions of the MAS 35x9F can be
extended or substituted by downloading up to
4 kWords (1 Word = 20 bits) of program code and
additionally up to 4 kWords of coefficients into the
internal RAM.
The MPEG decoder provides an automatic standard
detection mode. If all MPEG audio decoders are
SDI
PIO
Encoder
Audio
Proc.
LINE IN
MIC IN
OUT
A/D
MIX
D/A
Fig. 2–2: Encoder signal flow
PIO
DSP
Volume
Matrix
S/PDIF
SDO
Decoder
SDIB
Audio
Proc.
LINE IN
MIC IN
OUT
A/D
MIX
D/A
Fig. 2–3: Decoder signal flow
Micronas
June 30, 2004; 6251-505-1DS
9
MICRONAS [ MICRONAS ]
