參數(shù)資料
型號(hào)： NSC800E
廠商： National Semiconductor Corporation
英文描述： NSC800TM High-Performance Low-Power CMOS Microprocessor
中文描述： NSC800TM高性能低功耗CMOS微處理器
文件頁(yè)數(shù)： 71/76頁(yè)
文件大?。?/td> 785K
代理商： NSC800E
13.0 Data Acquisition System
(Continued)
ing. When in the power-save mode, the system power re-
quirements are decreased by about 50%, thus extending
battery life.
Communication with the peripheral devices (MM58167 and
ADC0816) is accomplished through the I/O ports of the
NSC810A and NSC831. The peripheral devices are not con-
nected to the bus of the NSC800 as they are not directly
compatible with a multiplexed bus structure. Therefore, ad-
ditional components would be required to place them on the
microprocessor bus. Writing data into the MM58167 is per-
formed by first putting the desired data on Port A, followed
by selecting the address of the internal register and applying
the chip select through the use of Port B. A bit set and clear
operation is performed to emulate a pulse on the bit of Port
B connected to the WR input of the MM58167. For a read
operation, the same sequence of operations is performed
except that Port A is set for the input mode of operation and
the RD line is pulsed. Similar techniques are used to read
converted data from the A/D converter. When a conversion
is desired, the CPU selects a channel and commands the
ADC0816 to start a conversion. When the conversion is
complete, the converter will produce an End-of-Conversion
signal which is connected to the RSTA interrupt input of the
NSC800.
When operating, the system shown consumes about 125
mw. When in the power-save mode, power consumption is
decreased to about 70 mw. If, as is likely, the system is in
the power-save mode most of the time, battery life can be
quite long depending on the amp-hour rating of the batteries
incorporated into the system. For example, if the battery
pack is rated at 5 amp-hours, the system should be able to
operate for about 400-500 hours before a battery charge or
change is required.
As shown in the schematic (refer toFigure 20), analog input
IN0 is connected to the battery source. In this way, the CPU
can monitor its own power source and notify the host that it
needs a battery replacement or charge. Since the battery
source shown is a stacked array of 7 NiCads producing
8.4V, the converter input is connected in the middle so that
it can take a reading on two or three of the cells. Since
NiCad batteries have a relatively constant voltage output
until very nearly discharged, the CPU can sense that the
‘‘knee’’ of the discharge curve has been reached and notify
the host.
Typical Timer Output Frequencies
Crystal Frequency
CPU Clock Output
Timer 0 Output
Timer 1 Output
2.097152 MHz
1.048576 MHz
262.144 kHz
divisor
e
4
32.768 kHz
divisor
e
8
3.276800 MHz
1.638400 MHz
327.680 kHz
divisor
e
5
32.768 kHz
divisor
e
10
4.194304 MHz
2.097152 MHz
262.144 kHz
divisor
e
8
32.768 kHz
divisor
e
8
4.915200 MHz
2.457600 MHz
491.520 kHz
divisor
e
5
32.768 kHz
divisor
e
15
71
相關(guān)PDF資料
PDF描述
NSC800N NSC800TM High-Performance Low-Power CMOS Microprocessor
NSC800V NSC800TM High-Performance Low-Power CMOS Microprocessor
NSC858 NSC858 Universal Asynchronous Receiver/Transmitter
NSC858D NSC858 Universal Asynchronous Receiver/Transmitter
NSC858E NSC858 Universal Asynchronous Receiver/Transmitter
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NSC800E-1M 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:8-Bit Microprocessor
NSC800E-3/883 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:8-Bit Microprocessor
NSC800E-3M 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:8-Bit Microprocessor
NSC800E-4 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:8-Bit Microprocessor
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