Typewriter User Manual

5- 78 MC68340 USER’S MANUAL MOTOROLA
Result Data:
Always returns 32 bits of data, regardless of the size of the register being read. If the
register is less than 32 bits, the result is returned zero extended.
Register Field:
The system control register is specified by the register field (see Table 5-24).
Table 5-24. Register Field for RSREG and WSREG
System Register Select Code
Return Program Counter (RPC)
0000
Current Instruction Program Counter (PCC)
0001
Status Register (SR)
1011
User Stack Pointer (USP)
1100
Supervisor Stack Pointer (SSP)
1101
Source Function Code Register (SFC)
1110
Destination Function Code Register (DFC)
1111
Temporary Register A (ATEMP)
1000
Fault Address Register (FAR)
1001
Vector Base Register (VBR)
1010
5.6.2.8.7 Write System Register (WSREG). Operand data is written into the specified
system control register. All registers that can be written in supervisor mode can be written
in BDM. Several internal temporary registers are also accessible.
Command Format:
1514131211109876543 0
001001001000 REGISTER
Command Sequence:
MS DATA
XXX
"ILLEGAL"
LS DATA
"NOT READY"
NEXT CMD
"NOT READY"
"CMD COMPLETE"
NEXT CMD
WSREG
???
"NOT READY"
Operand Data:
The data to be written into the register is always supplied as a 32-bit long word. If the
register is less than 32 bits, the least significant word is used.
Result Data:
“Command complete” status is returned when register write is complete.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
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