Motorola ColdFire MCF5281 - Manual (Page 652)

Debug Support
30-34 Freescale Semiconductor
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
Section 3.3.1.2, “Saving and Restoring the EMAC Programming Model ”.
30.5.3.3.10 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 30-35. WCREG Command/Result Formats
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3