MC68HC908LJ24 Datasheet, PDF (172/464 Pages) Motorola, Inc – Microcontrollers

Monitor ROM (MON)
Table 10-3 lists external frequencies required to achieve a standard
baud rate of 9600 BPS. Other standard baud rates can be accomplished
using proportionally higher or lower frequency generators. If using a
crystal as the clock source, be aware of the upper frequency limit that the
internal clock module can handle.
Table 10-3. Monitor Baud Rate Selection
External
Frequency
4.9152 MHz
9.8304 MHz
9.8304 MHz
32.768 kHz
IRQ
V_TST
V_TST
V_DD
V_SS
PTC1
0
1
X
X
Internal
Frequency
2.4576 MHz
2.4576 MHz
2.4576 MHz
2.4576 MHz
Baud Rate
(BPS)
9600
9600
9600
9600
10.4.5 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)
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.
Data Sheet
172
Monitor ROM (MON)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor