NSC800N-1 National Semiconductor, NSC800N-1 Datasheet - Page 71

• Manufacturer Part Number: NSC800N-1
• Description: IC CPU 8BIT 1MHZ 40-DIP
• Manufacturer: National Semiconductor

Specifications of NSC800N-1

• Processor Type: 8-Bit CMOS
• Speed: 1MHz
• Voltage: 4.5 ~ 5.5V
• Mounting Type: Through Hole
• Package / Case: 40-DIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Other names: *NSC800N-1; NSC800; NSC800-1

13 0 Data Acquisition System
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
Crystal Frequency
2 097152 MHz
3 276800 MHz
4 194304 MHz
4 915200 MHz
CPU Clock Output
1 048576 MHz
1 638400 MHz
2 097152 MHz
2 457600 MHz
Typical Timer Output Frequencies
(Continued)
71
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 to Figure 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
Timer 0 Output
262 144 kHz
327 680 kHz
262 144 kHz
491 520 kHz
divisor
divisor
divisor
divisor
e
e
e
e
4
5
8
5
Timer 1 Output
divisor
divisor
32 768 kHz
divisor
32 768 kHz
32 768 kHz
divisor
32 768 kHz
e
e
e
e
10
15
8
8