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USB-2623 User's Guide Functional Details
Counter input
The four counter inputs (
CNT0
to
CNT3
) are 32-bit event counters that can accept frequency inputs up to
20 MHz.
Figure 11. Typical counter input
Counter input connections are available on the SCSI connector and header connector J4.
Trigger input
The external digital trigger input (
TTLTRIG)
is software selectable for edge or level sensitive.
Edge sensitive mode is configurable for rising or falling edge.
Level sensitive mode is configurable for high or low level.
The default setting at power up is edge sensitive, rising edge. The trigger input connection is available on the
SCSI connector and header connectors J4 and J5.
Timer output
The four timer outputs (
TMR0
to
TMR3
) are pulse width modulation (PWM) outputs that can generate a square
schematic.
Figure 12. Typical timer output
Timer output connections are available on the SCSI connector and header connectors J4 and J5. TMR0 and
TMR1 are available on the SCSI connector and header connector J4. TMR2 and TMR3 are available on header connector J5.
Ground
The analog ground (
AGND
) pins provide a common ground for all analog channels. The digital ground (
GND
) pins provide a common ground for the digital, counter, timer, and clock channels and the power terminal.
Power output
The
+VO
pin can output up to 10 mA maximum. Use this terminal to power external devices or circuitry. Power output connections are available on the SCSI connector and header connectors J4 and J5.
Caution! The
+VO
(+5V) terminal is an output. Do not connect to an external power supply or you may damage the device and possibly the computer.
USB power
The maximum current that can be drawn by the device is 500 mA. This maximum applies to most personal computers and self-powered USB hubs. Bus-powered hubs and notebook computers may limit the maximum available output current to 100 mA. If the current requirement of the device exceeds the current available from the computer, connect to a self-powered hub or power the computer with an external power adapter.
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