BREAKPOINT OPERATION FLOW
CPU32
PERIPHERAL
ACKNOWLEDGE BREAKPOINT
IF BREAKPOINT INSTRUCTION EXECUTED:
1) SET R/W TO READ
2) SET FUNCTION CODE TO CPU SPACE
3) PLACE CPU SPACE TYPE 0 ON ADDR[19:16]
4) PLACE BREAKPOINT NUMBER ON ADDR[4:2]
5) CLEAR T-BIT (ADDR1) TO ZERO
6) SET SIZE TO WORD
7) ASSERT AS AND DS
IF BKPT PIN ASSERTED:
1) SET R/W TO READ
2) SET FUNCTION CODE TO CPU SPACE
3) PLACE CPU SPACE TYPE 0 ON ADDR[19:16]
4) PLACE ALL ONES ON ADDR[4:2]
5) SET T-BIT (ADDR1) TO ONE
6) SET SIZE TO WORD
IF BKPT INSTRUCTION EXECUTED:
1) PLACE REPLACEMENT OPCODE ON DATA BUS
2) ASSERT DSACK
OR:
7) ASSERT AS AND DS
1) ASSERT BERR TO INITIATE EXCEPTION PROCESSING
IF BKPT ASSERTED:
1) ASSERT DSACK
IF BREAKPOINT INSTRUCTION EXECUTED AND
DSACK IS ASSERTED:
OR:
1) LATCH DATA
2) NEGATE AS AND DS
3) GO TO (A)
1) ASSERT BERR TO INITIATE EXCEPTION PROCESSING
4
IF BKPT PIN ASSERTED AND
DSACK IS ASSERTED:
1) NEGATE AS AND DS
2) GO TO (A)
IF BERR ASSERTED:
1) NEGATE AS AND DS
2) GO TO (B)
(B)
(A)
IF BKPT INSTRUCTION EXECUTED:
1) PLACE LATCHED DATA IN INSTRUCTION PIPELINE
2) CONTINUE PROCESSING
1) NEGATE DSACK OR BERR
IF BKPT PIN ASSERTED:
1) CONTINUE PROCESSING
IF BKPT INSTRUCTION EXECUTED:
1) INITIATE ILLEGAL INSTRUCTION PROCESSING
IF BKPT PIN ASSERTED:
1) INITIATE HARDWARE BREAKPOINT PROCESSING
1110A
Figure 4-12 Breakpoint Operation Flowchart
MC68331
SYSTEM INTEGRATION MODULE
MOTOROLA
4-29
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
