Chapter 5 Background Debug Controller (S12ZBDCV2)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
Freescale Semiconductor
167
command following a single ERASE_FLASH initializes the sequence, such that thereafter the
ERASE_FLASH must be applied twice in succession to request a mass erase. If 512 BDCSI clock cycles
elapse between the consecutive ERASE_FLASH commands then a timeout occurs, which forces a soft
reset and initializes the sequence. The ERASE bit is cleared when the mass erase sequence has been
completed. No ACK is driven.
During the mass erase operation, which takes many clock cycles, the command status is indicated by the
ERASE bit in BDCCSR. Whilst a mass erase operation is ongoing, Always-available commands can be
issued. This allows the status of the erase operation to be polled by reading BDCCSR to determine when
the operation is finished.
The status of the flash array can be verified by subsequently reading the flash error flags to determine if
the erase completed successfully.
ERASE_FLASH can be aborted by a SYNC pulse forcing a soft reset.
NOTE: Device Bus Frequency Considerations
The ERASE_FLASH command requires the default device bus clock
frequency after reset. Thus the bus clock frequency must not be changed
following reset before issuing an ERASE_FLASH command.
5.4.4.20
STEP1
This command is used to step through application code. In active BDM this command executes the next
CPU instruction in application code. If enabled an ACK is driven.
If a STEP1 command is issued and the CPU is not halted, the command is ignored.
Using STEP1 to step through a CPU WAI instruction is explained in
.
5.4.5
BDC Access Of Internal Resources
Unsuccessful read accesses of internal resources return a value of 0xEE for each data byte. This enables a
debugger to recognize a potential error, even if neither the ACK handshaking protocol nor a status
command is currently being executed. The value of 0xEE is returned in the following cases.
•
Illegal address access, whereby ILLACC is set
•
Invalid READ_SAME or DUMP_MEM sequence
•
Invalid READ_Rn command (BDM inactive or CRN incorrect)
•
Internal resource read with timeout, whereby NORESP is set
Step1
Active Background
0x09
host
target
D
A
C
K
