MC68HC908RF2 Datasheet, PDF (156/254 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Monitor Read-Only Memory (MON)
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.
Any result of a command appears after the echo of the last byte of the
command.
SENT TO
MONITOR
ECHO
READ
READ
ADDR. HIGH ADDR. HIGH ADDR. LOW ADDR. LOW
1
3
1
3
1
2
Notes: 1 = Echo delay (2 bit times)
2 = Data return delay (2 bit times)
3 = Wait 1 bit time before sending next byte.
DATA
RESULT
Figure 10-4. Read Transaction
10.4.4 Break Signal
A start bit followed by nine low bits is a break signal. (See Figure 10-5.)
When the monitor receives a break signal, it drives the PTA0 pin high for
the duration of two bits before echoing the break signal.
MISSING STOP BIT
2-STOP-BIT DELAY BEFORE ZERO ECHO
01234567
01234567
Figure 10-5. Break Transaction
Advance Information
156
Monitor Read-Only Memory (MON)
MC68HC908RF2 — Rev. 1
MOTOROLA