mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 137

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

15.3.5 Commands
The monitor ROM firmware uses these commands:
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.
Freescale Semiconductor
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READ (read memory)
WRITE (write memory)
IREAD (indexed read)
IWRITE (indexed write)
READSP (read stack pointer)
RUN (run user program)
ECHO
Notes:
3
4
Wait one bit time after each echo before sending the next byte.
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.
ECHO
Notes:
WRITE
1 = Echo delay, 2 bit times
FROM
HOST
FROM
HOST
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
READ
1
1
WRITE
READ
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
3
4
ADDRESS
ADDRESS
HIGH
HIGH
Figure 15-5. Read Transaction
Figure 15-6. Write Transaction
1
1
ADDRESS
ADDRESS
HIGH
HIGH
4
3
ADDRESS
ADDRESS
NOTE
LOW
LOW
1
1
ADDRESS
ADDRESS
LOW
LOW
3
DATA
3, 2
1
DATA
DATA
RETURN
4
2, 3
Functional Description
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