MC68HC908JK8CP Freescale Semiconductor, MC68HC908JK8CP Datasheet - Page 88

• Manufacturer Part Number: MC68HC908JK8CP
• Manufacturer: Freescale Semiconductor

Specifications of MC68HC908JK8CP

• Cpu Family: HC08
• Device Core Size: 8b
• Frequency (max): 8MHz
• Interface Type: SCI
• Program Memory Type: Flash
• Program Memory Size: 8KB
• Total Internal Ram Size: 256Byte
• # I/os (max): 15
• Number Of Timers - General Purpose: 4
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 13-chx8-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 20
• Package Type: PDIP
• Lead Free Status / Rohs Status: Not Compliant

Monitor ROM (MON)
including the PTB3 frequency divisor selection, are not in effect. This is to reduce circuit requirements
when performing in-circuit programming.
Entering monitor mode with the reset vector being blank, the COP is always disabled regardless of the
state of IRQ or the RST.
Figure
= V
Enter monitor mode with the pin configuration shown above by pulling RST low and then high. The rising
edge of RST latches monitor mode. Once monitor mode is latched, the values on the specified pins can
change.
Once out of reset, the MCU waits for the host to send eight security bytes. (See
security bytes, the MCU sends a break signal (10 consecutive logic zeros) to the host, indicating that it is
ready to receive a command. The break signal also provides a timing reference to allow the host to
determine the necessary baud rate.
In monitor mode, the MCU uses different vectors for reset, SWI, and break interrupt. The alternate vectors
are in the $FE page instead of the $FF page and allow code execution from the internal monitor firmware
instead of user code.
Table 7-2
88
DD
. An OSC1 frequency of 9.8304MHz is required for a baud rate of 9600.
7-2. shows a simplified diagram of the monitor mode entry when the reset vector is blank and IRQ
is a summary of the vector differences between user mode and monitor mode.
MC68HC908JL8/JK8 • MC68HC08JL8/JK8 • MC68HC908KL8 Data Sheet, Rev. 3.1
Figure 7-2. Low-Voltage Monitor Mode Entry Flowchart
MONITOR MODE
TRIGGERED?
POR RESET
IS VECTOR
EXECUTE
MONITOR
BLANK?
CODE
POR
YES
YES
NO
NO
NORMAL USER
MODE
7.4
Freescale Semiconductor
Security.) After the