Datasheet

Monitor ROM (MON)
Technical Data MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
170 Monitor ROM (MON) Freescale Semiconductor
10.4.3 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. (See Figure 10-3 and Figure 10-4.)
Figure 10-3. Monitor Data Format
Figure 10-4. Sample Monitor Waveforms
The data transmit and receive rate can be anywhere from 4800 baud to
28.8k-baud. Transmit and receive baud rates must be identical.
10.4.4 Echoing
As shown in Figure 10-5, the monitor ROM immediately echoes each
received byte back to the PTA0 pin for error checking.
Figure 10-5. 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. HIGHREADREAD ADDR. HIGH ADDR. LOW ADDR. LOW DATA
ECHO
SENT TO
MONITOR
RESULT