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OnCE Module Architecture

12.3.3 OnCE State Machine and Control Block

The OnCE state machine has the following states:

IDLE—Do nothing

STATCOM—Poll status and get command

DEC1—Decode 1

DEC2—Decode 2

RWREG—Read/write a OnCE register

WPDBR—Write OPDBR

Figure 12-5 shows the possible paths through the OnCE state machine. Table 12-3 on page 12-11 gives a description of each state transition (as shown in Figure 12-5).

 

OnCE™ Module

12-9

OnCE™ Module

 

 

 

 

19

 

 

1

 

IDLE

 

 

 

 

 

 

18

 

 

 

 

2

 

 

 

 

 

 

 

17

 

 

 

STATCOM

 

 

 

3

(Poll Status &

 

 

 

 

Get Command)

 

 

 

 

 

 

12

13

 

 

 

4

 

 

20

10

 

 

 

 

 

 

 

 

 

RWREG

 

 

 

11

(Read/Write a

 

 

 

 

OnCE Register)

 

 

 

 

7

8

 

 

 

DEC1

 

 

 

 

5

6

 

 

 

 

 

DEC2

 

 

 

 

 

 

 

9

15

 

 

 

 

14

 

 

 

 

 

16

 

 

 

 

WPDBR

 

 

 

 

 

(Write OPDBR)

 

 

 

 

 

AA0116

Figure 12-5. OnCE State Machine

12-10

DSP56824 User’s Manual

 

 

OnCE Module Architecture

 

Table 12-3. OnCE State Machine Transitions

 

 

Transition

Description

 

 

 

 

1

Chip is in normal mode.

 

 

2

Chip enters debug mode. Go to STATCOM state.

 

 

3

Get command. Wait for the external controller to finish sending an 8-bit command.

 

 

4

External controller has finished sending the command. Start decoding OnCE command.

 

 

5

OnCE will not access any registers. The core is to repeat executing the previous instruction.

 

 

6

OnCE is to access a dedicated register. This is the default state when the OnCE command

 

selects a reserved option.

 

 

7

Read or write any OnCE dedicated register besides the PDB register, OBDBR. The core will not

 

be asked to execute any instruction.

 

 

8

Read OPDBR. The core will not be asked to execute any instruction.

 

 

9

Write to the OPDBR. The core will eventually be asked to execute an instruction.

 

 

10

OnCE is to clear either the OnCE breakpoint counter (OMBC) or the OnCE trace counter (OTC).

 

 

11

Read or write the OnCE dedicated register. Wait for 16 input or output bits to be shifted.

 

 

12

Finished writing a OnCE register. Send an acknowledge pulse.

 

 

13

Finished writing a OnCE register. Do not send an acknowledge pulse.

 

 

14

Write to the OPDBR. Wait for the 16-bit core command or operand to be shifted.

 

 

15

Finished writing to the OPDBR. Execute a one-word core instruction, but do not exit from debug

 

mode.

 

 

16

Finished writing to the OPDBR. Execute a two-word core instruction, but do not exit from debug

 

mode.

 

 

17

Finished writing to the OPDBR. Transfer its contents to the PDB. This is the first word of a

 

two-word instruction. Get the second word.

 

 

18

Finished writing to the OPDBR. Execute a one-word core instruction while exiting the OnCE

 

debug mode.

 

 

19

Finished writing to the OPDBR. Execute a two-word core instruction while exiting the OnCE

 

debug mode.

 

 

20

The core has finished executing the current instruction. Get the next OnCE command.

 

 

 

OnCE™ Module

12-11

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