adau1442 Analog Devices, Inc., adau1442 Datasheet - Page 63

• Manufacturer Part Number: adau1442
• Description: Sigmadsp Digital Audio Processor With Flexible Audio Routing Matrix
• Manufacturer: Analog Devices, Inc.

RAMS
The ADAU144x has 4k words of program RAM, 4k words of
parameter RAM, and 8k words of data RAM.
Program RAM
Table 45. Register Details of Program RAM
Decimal
8192
The program RAM contains the 43-bit operation codes that are
executed by the core. It is important to note that although the
length of the RAM is 4096, only 3584 instructions can be
executed in the span of a single frame for normal rate signals.
For double rate processing, the maximum allowable instruction
count is 1792, and for quad rate processing, the maximum
allowable instruction count is 896. For more information on
setting the DSP core rate, see the DSP Core Rate Select Register
(Address 0xE220) section.
The additional program space can be utilized with optimized
algorithms and jump commands. The SigmaStudio compiler
calculates maximum instructions per frame for a project and
generates an error when the value exceeds the maximum allowable
instructions per frame based on the sample rate of the signals in
the core.
Because the end of a program contains a jump-to-start
command, the remaining program RAM space does not need to
be filled with no-operation (NOP) commands.
Program Counter Peak Count Register (Address 0xE229)
Table 46. Bit Descriptions of Register 0xE229
Bit Position
[15:0]
This 16-bit, read-only register keeps track of how many cycles
have elapsed from the start of the program until the program
counter is reset. The register is updated on every start pulse.
This register should not be used if the watchdog error sticky bit
has been activated, which indicates that the maximum allowable
clock cycles per frame have been exceeded. In this case, the
program counter peak value may be inaccurate.
Address
Hex
2000
Description
Program counter peak count (read only)
Name
Program RAM
Read/Write
Word Length
43 bits (6 bytes)
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Parameter RAM
Table 47. Register Details of Parameter RAM
Decimal
0
The parameter RAM contains all 28-bit values that are utilized
by algorithms running in the DSP core. SigmaStudio
automatically assigns the first eight positions to safeload
parameters; therefore, project-specific parameters start at
Address 0x0008.
Data RAM
Table 48. Register Details of Data RAM
Decimal
16384
The data RAM stores audio data that needs to be accessed by
the core for more than one frame. Unlike previous generations
of SigmaDSP architectures, which utilized a hardware-based
modulo structure, the ADAU144x has a software-based modulo
scheme that is controlled by the programmer.
The data RAM should be initialized to all 0s before a boot-up
operation is performed to avoid an undefined startup state.
SigmaStudio inserts the appropriate data RAM initialization
code into projects by default.
Modulo Data Memory Register (Address 0xE21F)
Table 49. Bit Descriptions of Register 0xE21F
Bit
Position
[15:14]
[13:0]
This is a single 14-bit register that sets the start of the
nonmodulo space of the data memory. The default value is
7936 decimal. SigmaStudio sets this value by default based on
the addressing scheme used in the SigmaStudio project. The
value should not be modified by the user.
Address
Address
Description
Reserved
Nonmodulo data memory start.
The setting is the address in
memory.
Hex
0000
Hex
4000
Name
Parameter RAM
Name
Data RAM
Read/Write
Word Length
28 bits (4 bytes)
Read/Write
Word Length
28 bits (4 bytes)
Default
01111100000000