Datasheet

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
122 Monitor ROM (MON) MOTOROLA
Monitor ROM (MON)
NON-DISCLOSURE AGREEMENT REQUIRED
9.4.6 Commands
The monitor ROM firmware uses these commands:
• READ (read memory)
• WRITE (write memory)
• IREAD (indexed read)
• IWRITE (indexed write)
• READSP (read stack pointer)
• RUN (run user program)
The monitor ROM firmware echoes each received byte back to the PTA0
pin for error checking. An 11-bit delay at the end of each command
allows the host to send a break character to cancel the command. A
delay of two bit times occurs before each echo and before READ,
IREAD, or READSP data is returned. The data returned by a read
command appears after the echo of the last byte of the command.
NOTE: Wait one bit time after each echo before sending the next byte.
Figure 9-7. Read Transaction
Figure 9-8. Write Transaction
READREAD
ECHO
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
RETURN
13, 2114
4
Notes:
2 = Data return delay, 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
44
1 = Echo delay, 2 bit times
WRITEWRITE
ECHO
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
Notes:
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
113113
3
32, 3
1 = Echo delay, 2 bit times