MC908JB12DWE Datasheet, PDF (130/332 Pages) Freescale Semiconductor, Inc – MC68HC908JB16 Technical Data

Monitor ROM (MON)
9.4.5 Commands
The monitor ROM uses the following 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.
FROM
HOST
READ
READ
ADDRESS ADDRESS ADDRESS ADDRESS
HIGH
HIGH
LOW
LOW
4
1
4
1
4
1
3, 2
ECHO
Notes:
1 = Echo delay, 2 bit times
2 = Data return delay, 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
Figure 9-5. Read Transaction
DATA
4
RETURN
Technical Data
130
Monitor ROM (MON)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor