MC908MR16CFUE Datasheet, PDF (260/282 Pages) Freescale Semiconductor, Inc – On-chip programming firmware for use with host personal computer, Clock generator module (CGM)

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18.3.1.5 Echoing
As shown in Figure 18-11, the monitor ROM immediately echoes each received byte back to the PTA0
pin for error checking.
SENT TO
MONITOR
READ
READ ADDR. HIGH ADDR. HIGH ADDR. LOW ADDR. LOW DATA
ECHO
RESULT
Figure 18-11. Read Transaction
Any result of a command appears after the echo of the last byte of the command.
18.3.1.6 Break Signal
A start bit followed by nine low bits is a break signal. See Figure 18-12. When the monitor receives a break
signal, it drives the PTA0 pin high for the duration of two bits before echoing the break signal.
MISSING STOP BIT
2--STOP-BIT DELAY BEFORE ZERO ECHO
01234567
01234567
Figure 18-12. Break Transaction
18.3.1.7 Commands
The monitor ROM uses these commands (see Table 18-3–Table 18-8):
• READ, read memory
• WRITE, write memory
• IREAD, indexed read
• IWRITE, indexed write
• READSP, read stack pointer
• RUN, run user program
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
260
Freescale Semiconductor