Motorola MCF5282, MCF5281 user manual Write Control Register Wcreg, Wcreg Command/Result Formats

Models: MCF5282 MCF5281

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Background Debug Mode (BDM)

As an example, any BDM read of an accumulator register (ACCn) must be preceded by two commands accessing the MAC status register. Specifically, the following BDM sequence is required:

BdmReadACCn (

 

 

 

 

 

 

rcreg

macsr;

//

read

macsr contents & save

wcreg

#0,macsr;

//

disable

all rounding

modes

rcreg

accn;

//

read

the desired accumulator

wcreg

#saved_data,macsr;//

restore

the original

macsr

)

Likewise, the following BDM sequence is needed to write an accumulator register:

BdmWriteACCn

(

 

 

 

 

rcreg

macsr;

//

read macsr contents & save

wcreg

#0,macsr;

//

disable

all rounding

modes

wcreg

#data,accn;

//

write the desired accumulator

wcreg

#saved_data,macsr;//

restore

the original

macsr

)

Additionally, it is required that writes to the accumulator extension registers be performed after the corresponding accumulators are updated. This is needed since a write to any accumulator alters the contents of the corresponding extension register.

For more information on saving and restoring the complete EMAC programming model, see appropriate section of the EMAC specification.

29.5.3.3.10 Write Control Register (WCREG)

The operand (longword) data is written to the specified control register. The write alters all 32 register bits.

Command/Result Formats:

15

12

11

8

7

4

3

0

Command

 

0x2

 

0x8

0x8

 

 

0x0

 

 

 

 

 

 

 

 

 

 

 

0x0

 

0x0

0x0

 

 

0x0

 

 

 

 

 

 

 

 

 

 

 

0x0

 

 

Rc

 

 

 

 

 

 

 

 

 

 

 

 

Result

 

 

 

D[31:16]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D[15:0]

 

 

 

 

 

 

 

 

 

 

 

 

Figure 29-35. WCREG Command/Result Formats

29-34

MCF5282 User’s Manual

MOTOROLA

Page 706
Image 706
Motorola MCF5282, MCF5281 user manual Write Control Register Wcreg, Wcreg Command/Result Formats