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Debug Module
34-31
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34.4.1.3.3
Extension Words as Required
Some commands require extension words for addresses and/or immediate data. Addresses require two
extension words because only absolute long addressing is permitted. Longword accesses are forcibly
longword-aligned and word accesses are forcibly word-aligned. Immediate data can be 1 or 2 words long.
Byte and word data each requires a single extension word, while longword data requires two extension
words.
Operands and addresses are transferred most-significant word first. In the following descriptions of the
BDM command set, the optional set of extension words is defined as address, data, or operand data.
34.4.1.4
Command Sequence Diagrams
The command sequence diagram in
shows serial bus traffic for commands. Each bubble
represents a 17-bit bus transfer. The top half of each bubble indicates the data the development system
sends to the debug module; the bottom half indicates the debug module’s response to the previous
development system commands. Command and result transactions overlap to minimize latency.
Figure 34-20. Command Sequence Diagram
3
A/D
Address/Data. Determines whether the register field specifies a data or address register.
0 Data register.
1 Address register.
2–0
Register
Contains the register number in commands that operate on processor registers. See
Table 34-24. BDM Field Descriptions (continued)
Field
Description
XXX
’NOT READY’
READ (LONG)
???
MS ADDR
’NOT READY’
LS ADDR
’NOT READY’
NEXT CMD
’NOT READY’
NEXT CMD
’NOT READY’
NEXT CMD
LS RESULT
Commands transmitted to the debug module
Command code transmitted during this cycle
High-order 16 bits of memory address
Low-order 16 bits of memory address
Non-serial-related
Next
Command
Code
Sequence taken if operation
has not completed
activity
READ
MEMORY
LOCATION
XXX
BERR
XXX
MS RESULT
XXX
’ILLEGAL’
Responses from the debug module
Results from previous command
Sequence taken if illegal command
is received by debug module
Data used from this transfer
Sequence taken if bus error
occurs on memory access
High- and low-order 16 bits of result
Summary of Contents for MCF54455
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Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
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