Freescale Semiconductor MC9S12ZVM series, Справочное руководство

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Chapter 5 Background Debug Controller (S12ZBDCV2)
MC9S12ZVM Family Reference Manual Rev. 1.3
Freescale Semiconductor 151
4
OVRUN
Overrun Flag — Indicates unexpected host activity before command completion.
This occurs if a new command is received before the current command completion.
With ACK enabled this also occurs if the host drives the BKGD pin low whilst a target ACK pulse is pending
To protect internal resources from misinterpreted BDC accesses following an overrun, internal accesses are
suppressed until a SYNC clears this bit.
A SYNC clears the bit.
0 No overrun detected.
1 Overrun detected when issuing a BDC command.
3
NORESP
No Response Flag — Indicates that the BDC internal action or data access did not complete. This occurs in
the following scenarios:
a) If no free cycle for an access is found within 512 core clock cycles. This could typically happen if a code loop
without free cycles is executing with ACK enabled and STEAL clear.
b) With ACK disabled or STEAL set, when an internal access is not complete before the host starts
data/BDCCSRL retrieval or an internal write access is not complete before the host starts the next BDC
command.
c) Attempted internal memory or SYNC_PC accesses during STOP mode set NORESP if BDCCIS is clear.
In the above cases, on setting NORESP, the BDC aborts the access if permitted. (For devices supporting
EWAIT, BDC external accesses with EWAIT assertions, prevent a command from being aborted until EWAIT
is deasserted).
d) If a BACKGROUND command is issued whilst the device is in wait mode the NORESP bit is set but the
command is not aborted. The active BDM request is completed when the device leaves wait mode.
Furthermore subsequent CPU register access commands during wait mode set the NORESP bit, should it
have been cleared.
e) If a command is issued whilst awaiting return from Wait mode. This can happen when using STEP1 to step
over a CPU WAI instruction, if the CPU has not returned from Wait mode before the next BDC command is
received.
f) If STEP1 is issued with the BDC enabled as the device enters Wait mode regardless of the BDMACT state.
When NORESP is set a value of 0xEE is returned for each data byte associated with the current access.
Writing a “1” to this bit, clears the bit.
0 Internal action or data access completed.
1 Internal action or data access did not complete.
2
RDINV
Read Data Invalid Flag — Indicates invalid read data due to an ECC error during a BDC initiated read access.
The access returns the actual data read from the location.
Writing a “1” to this bit, clears the bit.
0 No invalid read data detected.
1 Invalid data returned during a BDC read access.
1
ILLACC
Illegal Access Flag — Indicates an attempted illegal access. This is set in the following cases:
When the attempted access addresses unimplemented memory
When the access attempts to write to the flash array
When a CPU register access is attempted with an invalid CRN (
Section 5.4.5.1 ).
Illegal accesses return a value of 0xEE for each data byte
Writing a “1” to this bit, clears the bit.
0 No illegal access detected.
1 Illegal BDC access detected.
Table 5-6. BDCCSRL Field Descriptions (continued)
Field Description