Motorola MC68340 manual Breakpoint Operation Flowchart

Freescale Semiconductor, Inc...

Freescale Semiconductor, Inc.

BREAKPOINT OPERATION FLOW EXTERNAL DEVICE

PROCESSOR

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 A19–A16

4.PLACE BREAKPOINT NUMBER ON A2–A4

5.CLEAR T-BIT (A1)

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 A19–A16

4.PLACE ALL ONE'S ON A4–A2

5.	SET T-BIT (A-1) TO ONE		IF BREAKPOINT INSTRUCTION EXECUTED:
			1.	PLACE REPLACEMENT OPCODE ON DATA BUS
6.	SET SIZE TO WORD
		2.		ASSERT DSACKx
7.	ASSERT AS AND DS
					-OR-
		1.		ASSERT BERR TO INITIATE EXCEPTION PROCESSING
			IF BKPT PIN ASSERTED:
		1.		ASSERT DSACKx
						-OR-
IF BREAKPOINT INSTRUCTION EXECUTED AND			1.	ASSERT BERR TO INITIATE EXCEPTION PROCESSING
DSACKx IS ASSERTED:

1.LATCH DATA

2.NEGATE AS AND DS

3.GO TO (A)

IF BKPT PIN ASSERTED AND DSACKx IS ASSERTED:

1.NEGATE AS AND DS

2.GO TO (A)

IF BERR ASSERTED:

1.NEGATE AS AND DS

2.GO TO (B)

(A) (B)

1. NEGATE DSACKx or BERR

IF BREAKPOINT INSTRUCTION EXECUTED:

1.PLACE LATCHED DATA IN INSTRUCTION PIPELINE

2.CONTINUE PROCESSING

IF BKPT PIN ASSERTED:

1. CONTINUE PROCESSING

IF BREAKPOINT INSTRUCTION EXECUTED:

1.INITIATE ILLEGAL INSTRUCTION PROCESSING IF BKPT PIN ASSERTED:

1.INITIATE HARDWARE BREAKPOINT PROCESSING

Figure 3-11. Breakpoint Operation Flowchart

3- 24MC68340 USER’S MANUALMOTOROLA

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