s908ey16g2vfar Freescale Semiconductor, Inc, s908ey16g2vfar Datasheet - Page 246

• Manufacturer Part Number: s908ey16g2vfar
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Development Support
19.3.1.6 Baud Rate
The monitor communication baud rate is controlled by the frequency of the external or internal oscillator
and the state of the appropriate pins as shown in
Table 19-1
effective baud rate is the internal operating frequency divided by 256. If using a crystal as the clock
source, be aware of the upper frequency limit that the internal clock module can handle. See
Control Timing
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. 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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•
•
•
•
•
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 9600 bps. The
2
Wait one bit time after each echo before sending the next byte.
for this limit.
ECHO
Notes:
ECHO
Notes:
3
WRITE
1 = Echo delay, approximately 2 bit times
2 = Wait approximately 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 = Wait approximately 1 bit time before sending next byte
FROM
HOST
READ
1
1
WRITE
MC68HC908EY16A • MC68HC908EY8A Data Sheet, Rev. 1
READ
2
ADDRESS
3
HIGH
ADDRESS
Figure 19-14. Read Transaction
Figure 19-15. Write Transaction
HIGH
1
ADDRESS
1
HIGH
ADDRESS
HIGH
2
ADDRESS
NOTE
3
Table
LOW
ADDRESS
LOW
1
19-1.
ADDRESS
1
LOW
ADDRESS
LOW
2
DATA
2
1
DATA
DATA
RETURN
3
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2
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