MAS3519F datasheet(28/92 Pages) MICRONAS

28 / 92 page

MAS 35x9F

DATA SHEET

June 30, 2004; 6251-505-1DS

Micronas

3.3.2. Data Formats

The internal data word size is 20 bits. All RAM-

addresses can be accessed in a 20-bit mode via I2C

bus. Because of the 16-bit width of the I2C data regis-

ter the full transfer of all 20 bits requires two 16-bit I2C

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.

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:

r = v*524288.0+0.5; (

−1.0 ≤ v < 1.0)

v = r/524288.0; (

−524288 < r < 524287)

3.3.2.1. Run and Freeze (Codes 0hex to 3hex)

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.

If the start address is 1000hex ≤ a < 3FFFhex and the

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.

Example 1: Start program execution at address

345hex:

Example 2: Start execution of a downloaded code at

address 1000hex:

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.

Freeze has the following I2C protocol:

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.

3.3.2.2. Read Register (Code Ahex)

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.

Example:

Read the content of register C8hex:

define register

and read

3.3.2.3. Write Register (Code Bhex)

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.

Example: Writing the value 81234hex into the register

with the number AAhex:

SDW

data_write

a3,a2

a1,a0

1) send command

2) get register value

SDW

data_write

a,r1

r0,0

SDW

data_read

d3,d2

d1,d0

x,d4

x,x

SDW

data_write

b,r1

r0,d4

d3,d2

d1,d0

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