s908ey8ad4cfjer Freescale Semiconductor, Inc, s908ey8ad4cfjer Datasheet - Page 236

• Manufacturer Part Number: s908ey8ad4cfjer
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Development Support
Table 19-1
effective baud rate is the bus frequency divided by 278. If using a crystal as the clock source, be aware
of the upper frequency limit that the internal clock module can handle. See
limit.
19.3.1.7 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.
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•
•
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READ (read memory)
WRITE (write memory)
IREAD (indexed read)
IWRITE (indexed write)
READSP (read stack pointer)
RUN (run user program)
also lists external frequencies required to achieve a standard baud rate of 7200 bps. The
3
Wait one bit time after each echo before sending the next byte.
ECHO
Notes:
ECHO
Notes:
4
WRITE
1 = Echo delay, approximately 2 bit times
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
FROM
HOST
1 = Echo delay, approximately 2 bit times
2 = Data return delay, approximately 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
FROM
HOST
READ
1
1
WRITE
READ
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
3
ADDRESS
4
HIGH
ADDRESS
Figure 19-14. Read Transaction
Figure 19-15. Write Transaction
HIGH
1
ADDRESS
1
HIGH
ADDRESS
HIGH
3
ADDRESS
NOTE
4
LOW
ADDRESS
LOW
1
ADDRESS
1
LOW
ADDRESS
LOW
3
DATA
3, 2
1
DATA
20.6 Control Timing
DATA
RETURN
4
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2, 3
for this