MC68HC908GR16 Datasheet, PDF (276/310 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Development Support
19.3.1.7 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)
NOTE:
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.
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
DATA
4
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.
RETURN
Figure 19-15. Read Transaction
FROM HOST
WRITE
WRITE
ADDRESS ADDRESS ADDRESS ADDRESS
HIGH
HIGH
LOW
LOW
DATA
DATA
3
1
3
1
3
1
3
1
2, 3
ECHO
Notes:
1 = Echo delay, 2 bit times
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
Figure 19-16. Write Transaction
Data Sheet
276
Development Support
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MC68HC908GR16 — Rev. 1.0
MOTOROLA