参数资料
型号: MC68HC05V7CB
厂商: FREESCALE SEMICONDUCTOR INC
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PDIP56
封装: SDIP-56
文件页数: 124/170页
文件大小: 980K
代理商: MC68HC05V7CB
SECTION 6: RESETS
MOTOROLA
Page 43
MC68HC05V7 Specification Rev. 1.0
Table 6-1:
COP Watchdog Timer Recommendations
6.2.3.5
COP REGISTER
The COP register is shared with the MSB of an unimplemented User Interrupt Vector as
shown in Figure 6-3. Reading this location will return whatever user data has been
programmed at this location. Writing a “0” to the COPR bit in this location will clear the COP
watchdog timer.
Figure 6-3:
COP Watchdog Timer Location
6.2.4
LOW-VOLTAGE RESET (LVR)
The internal low voltage (LVR) reset is generated when VDD falls below the LVR threshold
VLVRI and will be released following a POR delay starting when VDD rises above VLVRR.
The LVR threshold is tested to be above the minimum operating voltage of the
microcontroller and is intended to ensure that the CPU will be held in reset when the VBATT
supply voltage is below reasonable operating limits. However, it should be noted that the
LVR monitors VDD not VBATT. A mask option is provided to disable the LVR when the
device is expected to normally operate at low voltages. Note that the V
DD rise and fall slew
rates (S
VDDR and SVDDF) must be within the specification for proper LVR operation. If the
specification is not met, the circuit will operate properly following a delay of V
DD/Slew rate.
The LVR will generate the RST signal that will reset the CPU and other peripherals. As it is
not possible to determine the level of the internal VDD at the point VBATT recovers (and POR
is not intended to detect a loss of VDD), an LVR will always recover using a POR delay. The
low voltage reset will activate the internal pulldown device connected to the RESET pin.
WAIT Time Less than
COP Time-Out
STOP Instruction
WAIT Time
THEN the
COP Watchdog Timer
should be as follows:
Disable COP
by mask option
converted to reset
Enable or disable COP
by mask option
WAIT Time More than
COP Time-Out
any length
WAIT Time
Acts as STOP
Disable COP
by mask option
converted to reset
IF the following conditions exist:
UNIMPLEMENTED VECTOR &
COP WATCHDOG TIMER
x
$3FF0
W
R
COPR
UNIMPLEMENTED
READ
WRITE
ADDR
1
0
2
3
4
5
6
7
REGISTER
x
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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