USB-231-OEM User's Guide
Functional Details
16
Trigger input
The
TRIG
connector is an external digital trigger input. The trigger mode is software-selectable for rising edge-
or falling edge detection.
Counter input
The
CTR
connector is a 32-bit counter that can count rising edges. Edges can only be counted up from 0.
Counting down is not supported – you cannot set the initial count to 100 and count down to 99, 98, 97.
USB signals, power (D–, D+, VBUS)
When using a USB connector on your motherboard to connect the USB-231-OEM to the USB host through the
34-pin connector, do not connect to the USB connector.
Status LED driver (LED)
The LED signal indicates the device status as shown in the following table:
LED State
Device Status
Off
Device is not connected or is in suspend mode.
On, not blinking
Device is connected and functioning normally.
Blinking
Device has encountered an error.
An open collector output drives the LED signal. For applications that use the LED signal, connect an external
pull-up resistor from the LED signal to an external voltage.
LED electrical characteristics are listed in the
To drive a status LED, refer to the circuit in Figure 8.
Figure 8. Circuit to drive a status LED