Chapter 4
Specifications
Typical for 25 °C unless otherwise specified.
Specifications in
italic text
are guaranteed by design.
Digital input/output
Table 4-1. Digital I/O specifications
Digital type
82C55
Number of I/O
24 (Port A Bit 0 through Port C Bit7)
Configuration
2 banks of 8 and 2 banks of 4 or
3 banks of 8
Pull up/pull-down configuration
All pins pulled up to Vs via 47K resistors (default). Selection available for
pull down to ground. Hardware selectable via zero ohm resistor.
Input high voltage
2.0 V min, 5.5 V absolute max
Input low voltage
0.8 V max, –0.5 V absolute min
Output high voltage (IOH = -2.5 mA)
3.0 V min
Output low voltage (IOH = -2.5mA)
0.4V max
Power up / reset state
Input mode
Counter
Table 4-2. Counter specifications
Pin name (Note 1)
CTR
Counter type
Event counter
Number of channels
1
Input source
CTR screw terminal
Resolution 32
bits
Schmidt trigger hysteresis
20 mV to 100 mV
Input leakage current
±1 µA
Maximum input frequency
1 MHz
High pulse width
500 ns min
Low pulse width
500 ns min
Input low voltage
0 V min, 1.0 V max
Input high voltage
4.0 V min, 15.0 V max
Note 1:
CTR is a Schmitt trigger input
Data transfer rates
Table 4-3. Data transfer rate specifications
Digital I/O transfer rates (software paced)
Digital input
62 port reads or single bit reads per second (typical)
Digital output
125port writes or single bit writes per second (typical)
Counter/timer read/write rates (software paced)
Counter read
62 port reads per second (typical)
Counter clear
125 port writes per second (typical)
4-1
Содержание USB-DIO24/37
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