Feasa 20-F, User Manual

Page: 17 / 132

FEASA LED ANALYSER
FUNCTIONAL VERSION
Trigger Port Control
The Feasa Led Analyser includes a Trigger function that allows an external signal to trigger a
capture. For Trigger Function to operate the LED Analyser must be connected from the 2-pin
Trigger Connector to the PC or Controller using the supplied serial cable (LA-TR-01). The
Trigger function must first be enabled by sending commands to the Led Analyser. The
capture is triggered by a high-to-low transition on the Trigger Pin. See the
External Trigger
Mode section of this manual for the programming details.
The layout of the Trigger Connector is shown above. The trigger is activated on the Trigger Pin.
This pin has an internal pull-up resistor to 3.3V. The Trigger is activated by driving this pin to
GND. The Trigger timing sequence is shown below.
When the Trigger is activated there is a 550ns +/- 50ns delay before the light capture begins. The
commands must be transmitted through the USB or Serial Port of the Led Analyser. The Feasa Terminal
program can be used to perform this task.
Trigger Connector
Pin Signal
1 Trigger Pin
2 GND
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17
Trigger Pin GND Pin
Trigger
Measure
550ns
3.3V
0V
Integration
Time