Freescale Semiconductor MC68HC08KH12 manual Monitor Data Format, Sample Monitor Waveforms

10.4.2 Data Format

Communication with the monitor ROM is in standard non-return-to-zero

(NRZ) mark/space data format. (See Figure 10-2and Figure 10-3.)

										NEXT
START										START
	BIT 0	BIT 1	BIT 2	BIT 3	BIT 4	BIT 5	BIT 6	BIT 7	STOP
BIT										BIT
									BIT

$A5

BREAK

Figure 10-2. Monitor Data Format

										NEXT
START										START
	BIT 0	BIT 1	BIT 2	BIT 3	BIT 4	BIT 5	BIT 6	BIT 7	STOP
BIT										BIT
									BIT
START									STOP
	BIT 0	BIT 1	BIT 2	BIT 3	BIT 4	BIT 5	BIT 6	BIT 7		NEXT
BIT									BIT
										START
										BIT

Figure 10-3. Sample Monitor Waveforms

The data transmit and receive rate can be anywhere from 4800 baud to 28.8 kbaud. Transmit and receive baud rates must be identical.

10.4.3 Echoing

As shown in Figure 10-4, the monitor ROM immediately echoes each received byte back to the PTA0 pin for error checking.

SENT TO

MONITOR

READ READ ADDR. HIGH ADDR. HIGH ADDR. LOW ADDR. LOW DATA

ECHO RESULT

Figure 10-4. Read Transaction

Any result of a command appears after the echo of the last byte of the

command.

Advance Information	MC68HC(7)08KH12 — Rev. 1.1
154	Freescale Semiconductor