Motorola CPU32 Reference Manual page 307

BKPT_TAG
- - - - - I ~)__-~~
SHIFT_ClK
-.------~~
RESET
FORCE_BGND
--~t!!...._~~
BKPTiOSClK
Figure 7-9. BKPT/DSCLK Logic Diagram
BKPT _TAG should be timed to the bus cycles since it is not latched. If extended
past the assertion of FREEZE, the negation of BKPT _TAG appears to the
CPU32 as the first OSCLK.
OSCLK is the gated serial clock. Normally high, it pulses low for each bit to be
transferred. At the end of the seventeenth clock period, it remains high until the
start of the next transmission. Clock frequency is implementation dependent
and may range from OC to the maximum specified frequency. Although
performance considerations might dictate a hardware implementation, software
solutions are not precluded, provided serial bus timing is maintained.
7.2.8 Command Set
Following is a description of the command set available in BOM.
7.2.8.1 Command Format
The following standard bit format is utilized by all BOM commands.
15
10 9 5 4 2 0
OPERATION REGISTER
EXTENSION WORD(S)
Operation Field:
Commands are distinguished by the operation field. This 6-bit field provides
for a maximum of 64 unique commands.
MOTOROLA
7-14
DEVELOPMENT SUPPORT CPU32 REFERENCE MANUAL