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Debug Module
34-29
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between each bit exchange. The msb is sent first. Because DSO changes state based on an internally
recognized rising edge of DSCLK, DSO cannot be used to indicate the start of a serial transfer. The
development system must count clock cycles in a given transfer. C0–C4 are described as:
•
C0: Set the state of the DSI bit
•
C1: First synchronization cycle for DSI (DSCLK is high)
•
C2: Second synchronization cycle for DSI (DSCLK is high)
•
C3: BDM state machine changes state depending upon DSI and whether the entire input data
transfer has been transmitted
•
C4: DSO changes to next value
NOTE
A not-ready response can be ignored except during a memory-referencing
cycle. Otherwise, the debug module can accept a new serial transfer after 32
processor clock periods.
34.4.1.3
Receive Packet Format
The basic receive packet consists of 16 data bits and 1 status bit
.
34.4.1.3.1
Transmit Packet Format
The basic transmit packet consists of 16 data bits and 1 reserved bit.
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
S
Data
Figure 34-17. Receive BDM Packet
Table 34-22. Receive BDM Packet Field Description
Field
Description
16
S
Status. Indicates the status of CPU-generated messages listed below. The not-ready response can be ignored
unless a memory-referencing cycle is in progress. Otherwise, the debug module can accept a new serial transfer
after 32 processor clock periods.
15–0
Data
Data. Contains the message to be sent from the debug module to the development system. The response message
is always a single word, with the data field encoded as shown above.
S
Data
Message
0
xxxx
Valid data transfer
0
FFFF
Status OK
1
0000
Not ready with response; come again
1
0001
Error-Terminated bus cycle; data invalid
1
FFFF
Illegal Command
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
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 ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...