MAS 35x9F
DATA SHEET
3.3.2. Data Formats
The entry point of the default software will be accessed
automatically after a reset, thus issuing a Run or
Freeze command is only necessary for starting down-
loaded software or special program modules which are
not part of the standard set.
The internal data word size is 20 bits. All RAM-
addresses can be accessed in a 20-bit mode via I C
bus. Because of the 16-bit width of the I C data regis-
ter the full transfer of all 20 bits requires two 16-bit I C
2
2
2
words. Some commands only access the lower 16 bits
of a cell. For fast access of internal DSP states the
processor core also has an address space of 256 data
registers.
3.3.2.2. Read Register (Code A
)
hex
1) send command
S
DW
W
A
data_write
A
a,r1
A
r0,0
W
W
A
N
P
P
The internal data format is a 20 bit two’s complement
denoted “r”. If in some cases a fixed point notation “v”
is necessary. The conversion between the two forms
of notation is done as follows:
2) get register value
S
DW
x,x
W
A
A
data_read
A
A
S
DR
W
A
x,d4
W
d3,d2
A
d1,d0
r = v*524288.0+0.5; (−1.0 ≤ v < 1.0)
v = r/524288.0; (−524288 < r < 524287)
The MAS 35x9F has an address space of 256 DSP-
registers. Some of the registers (r = r1,r0 in the figure
above) are direct control inputs for various hardware
blocks, others control the internal program flow. In
Table 3–7, the registers of interest are described in
detail. In contrast to memory cells, registers cannot be
accessed as a block but must always be addressed
individually.
3.3.2.1. Run and Freeze (Codes 0
to 3
)
hex
hex
S
DW
W
A
data_write
A
a3,a2
A
a1,a0
W
A
P
The Run command causes the start of a program part
at address a = (a3,a2,a1,a0). Since nibble a3 is also
the command code (see Table 3–5), it is restricted to
values between 0 and 3. This command is used to
start alternate code or downloaded code from a RAM-
area that has been configured as program RAM.
Example:
Read the content of register C8
:
hex
<DW 68 ac 80>
<DW 69 <DR xx xd dd dd >
define register
and read
If the start address is 1000
≤ a < 3FFF
and the
hex
hex
3.3.2.3. Write Register (Code B
)
hex
respective RAM area has been configured as program
RAM (see Table 3–7 on page 31), the MAS 35x9F
continues execution with a custom program already
downloaded to this area.
S
DW
W
A
data_write
A
b,r1
A
A
r0,d4
d1,d0
W
W
A
A
d3,d2
P
Example 1: Start program execution at address
The controller writes the 20-bit value (d = d4,d3,d2,
d1,d0) into the MAS 35x9F register (r = r1,r0). A list of
registers needed for control purposes is given in Table
3–7.
345
:
hex
<DW 68 03 45>
Example 2: Start execution of a downloaded code at
Example: Writing the value 81234
into the register
hex
address 1000
:
hex
with the number AA
:
hex
<DW 68 10 00>
<DW 68 ba a8 12 34>
Freeze is a special run command with start address 0.
It suspends all normal program execution. The operat-
ing system will enter an idle loop so that all registers
and memory cells can be watched. This state is useful
for operations like downloading code or contents of
memory cells because the internal program cannot
overwrite these values. This freezing will be required if
alternative software is downloaded into the internal
RAM of the MAS 35x9F.
2
Freeze has the following I C protocol:
<DW 68 00 00>
28
June 30, 2004; 6251-505-1DS
Micronas
MICRONAS [ MICRONAS ]
