Adlink USB-2405 Bedienungsanleitung PDF herunterladen (Seite 49)

Operation 39

USB-2405

re-trigger number are valid from 1 to the buffer size allocated in

kernel space. The process repeats until the specified amount of

re-trigger signals is detected.

3.4 Programmable Function I/O

The USB-2405 supports powerful programmable I/O function pro-

vided by an FPGA chip, configurable as static digital input/output,

32-bit frequency counters, pulse output, synchronization sample

clock IN, and trigger IN. These signals are single-ended and 3.3 V/

TTL-compliant.

3.4.1 Static Digital Input/Output

Programmable function I/O can be used as static digital inputs or

outputs, with I/O lines readable and writeable by software polling,

with sample and update rate fully controlled by software timing.

3.4.2 Frequency Counter

Calculates base clocks occurring within a period (rising edge to

rising edge or falling edge to falling edge) of the repetitive input

signal, which is then converted to frequency value. Counter polar-

ity can be adjusted to rising edge active or falling edge active, with

maximum frequency measurable of 4MHz.

3.4.3 Pulse Output

The GPIO can also simulate a pulse output. By setting a varying

amount of Pulse_initial_cnt and Pulse_length_cnt, varying pulse

frequencies and duty cycles can be obtained. The maximum out-

put frequency is 4MHz, as shown.

Pulse_initial_count=7 Pulse_length_count=8

Timebase

PWM OUT

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Adlink USB-2405 Bedienungsanleitung Seite 49