參數(shù)資料
型號(hào)： P80C52SFPN
廠商： NXP SEMICONDUCTORS
元件分類： 微控制器/微處理器
英文描述： 80C51 8-bit microcontroller family 8K.64K/256.1K OTP/ROM/ROMless, low voltage 2.7V.5.5V, low power, high speed 33 MHz
中文描述： 8-BIT, MROM, 16 MHz, MICROCONTROLLER, PDIP40
封裝： 0.600 INCH, PLASTIC, MO-015, SOT129-1, DIP-40
文件頁數(shù)： 31/56頁
文件大小： 337K
代理商： P80C52SFPN
Philips Semiconductors
Product specification
8XC52/54/58/80C32
8XC51FA/FB/FC/80C51FA
8XC51RA+/RB+/RC+/RD+/80C51RA+
80C51 8-bit microcontroller family
8K–64K/256–1K OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33MHz)
1999 Apr 01
31
(8XC51FX and 8XC51RX+ ONLY)
––
ECOMn
CAPPn
CAPNn
MATn
TOGn
PWMn
ECCFn
CCAPM4
(DEH)
CH
CL
CCAP4H
CCAP4L
RESET
PCA TIMER/COUNTER
X
0
0
0
16–BIT COMPARATOR
MATCH
ENABLE
WRITE TO
CCAP4H
RESET
WRITE TO
CCAP4L
0
1
1
CMOD
(D9H)
CIDL
WDTE
––
––
––
CPS1
CPS0
ECF
X
SU00832
MODULE 4
Figure 25. PCA Watchdog Timer m(Module 4 only)
PCA Watchdog Timer
An on-board watchdog timer is available with the PCA to improve
the reliability of the system without increasing chip count. Watchdog
timers are useful for systems that are susceptible to noise, power
glitches, or electrostatic discharge. Module 4 is the only PCA
module that can be programmed as a watchdog. However, this
module can still be used for other modes if the watchdog is not
needed.
Figure 25 shows a diagram of how the watchdog works. The user
pre-loads a 16-bit value in the compare registers. Just like the other
compare modes, this 16-bit value is compared to the PCA timer
value. If a match is allowed to occur, an internal reset will be
generated. This will not cause the RST pin to be driven high.
In order to hold off the reset, the user has three options:
1. periodically change the compare value so it will never match the
PCA timer,
2. periodically change the PCA timer value so it will never match
the compare values, or
3. disable the watchdog by clearing the WDTE bit before a match
occurs and then re-enable it.
The first two options are more reliable because the watchdog timer
is never disabled as in option #3. If the program counter ever goes
astray, a match will eventually occur and cause an internal reset.
The second option is also not recommended if other PCA modules
are being used. Remember, the PCA timer is the time base for
all
modules; changing the time base for other modules would not be a
good idea. Thus, in most applications the first solution is the best
option.
Figure 26 shows the code for initializing the watchdog timer.
Module 4 can be configured in either compare mode, and the WDTE
bit in CMOD must also be set. The user’s software then must
periodically change (CCAP4H,CCAP4L) to keep a match from
occurring with the PCA timer (CH,CL). This code is given in the
WATCHDOG routine in Figure 26.
This routine should not be part of an interrupt service routine,
because if the program counter goes astray and gets stuck in an
infinite loop, interrupts will still be serviced and the watchdog will
keep getting reset. Thus, the purpose of the watchdog would be
defeated. Instead, call this subroutine from the main program within
2
16
count of the PCA timer.
相關(guān)PDF資料
PDF描述
P87C52SFPN 80C51 8-bit microcontroller family 8K.64K/256.1K OTP/ROM/ROMless, low voltage 2.7V.5.5V, low power, high speed 33 MHz
P80C52UFAA 80C51 8-bit microcontroller family 8K.64K/256.1K OTP/ROM/ROMless, low voltage 2.7V.5.5V, low power, high speed 33 MHz
P87C52UFAA 80C51 8-bit microcontroller family 8K.64K/256.1K OTP/ROM/ROMless, low voltage 2.7V.5.5V, low power, high speed 33 MHz
P80C52UFBB 80C51 8-bit microcontroller family 8K.64K/256.1K OTP/ROM/ROMless, low voltage 2.7V.5.5V, low power, high speed 33 MHz
P87C52UFBB 80C51 8-bit microcontroller family 8K.64K/256.1K OTP/ROM/ROMless, low voltage 2.7V.5.5V, low power, high speed 33 MHz
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
P80C52T-12 制造商:未知廠家 制造商全稱:未知廠家 功能描述:8-Bit Microcontroller
P80C52T-16 制造商:未知廠家 制造商全稱:未知廠家 功能描述:8-Bit Microcontroller
P80C52T-20 制造商:未知廠家 制造商全稱:未知廠家 功能描述:8-Bit Microcontroller
P80C52T2-1 制造商:未知廠家 制造商全稱:未知廠家 功能描述:8-Bit Microcontroller
P80C52T-25 制造商:未知廠家 制造商全稱:未知廠家 功能描述:8-Bit Microcontroller
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