MC68HC08AZ32A Datasheet, PDF (165/456 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Monitor ROM (MON)
Functional description
bytes. If the reset was not a power-on reset, security remains bypassed
regardless of the data that the host sends.
If the received bytes do not match the data at locations $FFF6–$FFFD,
the host fails to bypass the security features. The MCU remains in
monitor mode, but reading ROM/EEPROM locations returns undefined
data, and trying to execute code from ROM causes an illegal address
reset. After the host fails to bypass security, any reset other than a
power-on reset causes an endless loop of illegal address resets.
After receiving the eight security bytes from the host, the MCU transmits
a break character signalling that it is ready to receive a command.
NOTE: The MCU does not transmit a break character until after the host sends
the eight security bytes.
V_DD
4096 + 32 CGMXCLK CYCLES
RST
24 BUS CYCLES (MINIMUM)
FROM HOST
PA0
FROM MCU
1
4
1
1
2
4
1
NOTE: 1 = Echo delay (2 bit times)
2 = Data return delay (2 bit times)
4 = Wait 1 bit time before sending next byte.
Figure 11-6. Monitor Mode Entry Timing
MC68HC08AZ32A — Rev 1.0
MOTOROLA
Monitor ROM (MON)
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Technical Data
165