External Sources; Divider (Osc Divider); Counter Operation - Measurement Computing USB-4301 User Manual

USB-4301 User's Guide
FREQ1
FREQ2
FREQ3
FREQ4
FREQ5

External sources

In addition to the five internal sources, the frequency source for the oscillator can be an input signal connected
to any of the five counter input pins (
can have a maximum frequency of 20 MHz on the counter input pins, and a maximum frequency of 7 MHz on
the gate pins.
The table below applies to all internal and external sources.
Source
CTRINPUT1
CTRINPUT2
CTRINPUT3
CTRINPUT4
CTRINPUT5
GATE1
GATE2
GATE3
GATE4
GATE5
FREQ1
FREQ2
FREQ3
FREQ4
FREQ5

Divider (OSC divider)

The signal output from the
16. For example, if you select a base frequency of 5.0000 MHz in InstaCal, and choose FREQ3 as the internal
frequency source (50.000 kHz from the Internal frequency values table above), and 8 as the oscillator divider,
the frequency of the signal at the OSC pin is (50.000 kHz / 8) = 6.2500 kHz.

Counter operation

Each of the five counters performs essentially the same function: their internal value either increments or
decrements on each rising or falling edge of their source signal. Since they are all 16-bit counters, they can
16
count up from 0 to 2
(TC); when counting down, 0 is the TC. There are a variety of configuration options that can
Terminal Count
be used to unlock the power of this basic functionality.
Internal frequency values for different base frequencies
1.0000 MHz 1.6667 MHz
1.0000 MHz 1.6667 MHz
100.00 kHz 166.67 kHz
10.000 kHz 16.667 kHz
1.0000 kHz 1.6667 kHz
100.00 Hz 166.67 Hz
–
INP1 INP5
Oscillator sources
Description
Counter 1 input pin
Counter 2 input pin
Counter 3 input pin
Counter 4 input pin
Counter 5 input pin
Counter 1 gate pin
Counter 1 gate pin
Counter 1 gate pin
Counter 1 gate pin
Counter 1 gate pin
Internal base frequency
Internal base frequency/10
Internal base frequency/100
Internal base frequency/1000
Internal base frequency/10,000
pin is the same frequency as the frequency source divided by a value from 1 to
OSC
-1 = 65,535, or down from 65,535 to 0. When counting up, 65,535 is considered to be the
3.3333 MHz
3.3333 MHz
333.33 kHz
33.333 kHz
3.3333 kHz
333.33 Hz
) or any of the five gate pins (
16
Functional Details
5.0000 MHz
5.0000 MHz
500.00 kHz
50.000 kHz
5.0000 kHz
500.00 Hz
– ). The input signal
GAT1 GAT5