Motorola MC68340 manual Chkstat MOVE.B SRA,D0

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Command Sequence:

CALL	MS ADDR	LS ADDR
???	"NOT READY"	"NOT READY"
	XXX	NEXT CMD
	"ILLEGAL"	"NOT READY"

STACK

RETURN PC

FREEZE

NEGATED

PREFETCH

STARTED

NORMAL

MODE

XXX	NEXT CMD
BERR/AERR	"NOT READY"

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Operand Data:

The 32-bit operand data is the starting location of the patch routine, which is the initial PC upon exiting BDM.

Result Data: None

As an example, consider the following code segment. It outputs a character from the MC68340 serial module channel A.

CHKSTAT:	MOVE.B	SRA,D0	Move serial status to D0
	BNE.B	CHKSTAT	Loop until condition true
	MOVE.B	TBA,OUTPUT	Transmit character

MISSING:	ANDI.B	#3,D0	Check for TxEMP flag
	RTS

BDM and the CALL command can be used to patch the code as follows:

1.Breakpoint user program at CHKSTAT

2.Enter BDM

3.Execute CALL command to MISSING

4.Exit BDM

5.Execute MISSING code

6.Return to user program

5.6.2.8.14Reset Peripherals (RST). RST asserts RESET for 512 clock cycles. The CPU is not reset by this command. This command is synonymous with the CPU RESET instruction.

MOTOROLAMC68340 USER’S MANUAL5- 85

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