Freescale Semiconductor MC68HC08KH12 - Manual (Page 154)

Advance Information MC68HC(7)08KH12 — Rev. 1.1
154 Freescale Semiconductor
10.4.2 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. (See
Figure 10-2 and Figure 10-3 .)
Figure 10-2. Monitor Data Format
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.
Figure 10-4. Read Transaction
Any result of a command appears after the echo of the last byte of the
command.
BIT 5
START
BIT BIT 0 BIT 1
NEXT
STOP
BIT
START
BIT BIT 2 BIT 3 BIT 4 BIT 6 BIT 7
BIT 5
START
BIT BIT 0 BIT 1
NEXT
STOP
BIT
START
BIT BIT 2 BIT 3 BIT 4 BIT 6 BIT 7
START
BIT BIT 0 BIT 1 NEXT
STOP
BIT
START
BIT
BIT 2
$A5
BREAK BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
ADDR. HIGH READ READ ADDR. HIGH ADDR. LOW ADDR. LOW DATA
ECHO
SENT TO
MONITOR
RESULT