5-20
MCF5272 User’s Manual
Background Debug Mode (BDM)
5.5.3.1 ColdFire BDM Command Format
All ColdFire Family BDM commands include a 16-bit operation word followed by an
optional set of one or more extension words, as shown in Figure 5-15.
Table 5-18 describes BDM fields.
5.5.3.1.1 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 and 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.
15
10
9
8
7
6
5
4
3
2
0
Operation
0
R/W
Op Size
0
0
A/D
Register
Extension Word(s)
Figure 5-15. BDM Command Format
Table 5-18. BDM Field Descriptions
Bit
Name
Description
15–10
Operation Specifies the command. These values are listed in Table 5-17.
9
0
Reserved
8
R/W
Direction of operand transfer.
0 Data is written to the CPU or to memory from the development system.
1 The transfer is from the CPU to the development system.
7–6
Operand
Size
Operand data size for sized operations. Addresses are expressed as 32-bit absolute values.
Note that a command performing a byte-sized memory read leaves the upper 8 bits of the
response data undefined. Referenced data is returned in the lower 8 bits of the response.
Operand Size
Bit Values
00 Byte
8 bits
01 Word
16 bits
10 Longword
32 bits
11 Reserved
—
5–4
00
Reserved
3
A/D
Address/data. Determines whether the register field specifies a data or address register.
0 Indicates a data register.
1 Indicates an address register.
2–0
Register
Contains the register number in commands that operate on processor registers.
Содержание DigitalDNA ColdFire MCF5272
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Страница 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Страница 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Страница 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
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