
Chapter 6 Background Debug Module (BDMV4) Block Description
Freescale Semiconductor
MC9S12Q128
171
Rev 1.10
Table 6-2. BDMSTS Field Descriptions
Field
Description
7
ENBDM
Enable BDM — This bit controls whether the BDM is enabled or disabled. When enabled, BDM can be made
active to allow rmware commands to be executed. When disabled, BDM cannot be made active but BDM
hardware commands are allowed.
0 BDM disabled
1 BDM enabled
Note: ENBDM is set by the rmware immediately out of reset in special single-chip mode. In secure mode, this
bit will not be set by the rmware until after the EEPROM and FLASH erase verify tests are complete.
6
BDMACT
BDM Active Status — This bit becomes set upon entering BDM. The standard BDM rmware lookup table is
then enabled and put into the memory map. BDMACT is cleared by a carefully timed store instruction in the
standard BDM rmware as part of the exit sequence to return to user code and remove the BDM memory from
the map.
0 BDM not active
1 BDM active
5
ENTAG
Tagging Enable — This bit indicates whether instruction tagging in enabled or disabled. It is set when the
TAGGO command is executed and cleared when BDM is entered. The serial system is disabled and the tag
function enabled 16 cycles after this bit is written. BDM cannot process serial commands while tagging is active.
0 Tagging not enabled or BDM active
1 Tagging enabled
4
SDV
Shift Data Valid — This bit is set and cleared by the BDM hardware. It is set after data has been transmitted as
part of a rmware read command or after data has been received as part of a rmware write command. It is
cleared when the next BDM command has been received or BDM is exited. SDV is used by the standard BDM
rmware to control program ow execution.
0 Data phase of command not complete
1 Data phase of command is complete
3
TRACE
TRACE1 BDM Firmware Command is Being Executed — This bit gets set when a BDM TRACE1 rmware
command is rst recognized. It will stay set as long as continuous back-to-back TRACE1 commands are
executed. This bit will get cleared when the next command that is not a TRACE1 command is recognized.
0 TRACE1 command is not being executed
1 TRACE1 command is being executed