LightCrafter offers several flexible trigger configurations. The trigger connector (J7) lies at the back of the System board (top board):
The pinout of J7 connector is:
Two matching four pin mating connector part numbers are:
The corresponding crimps part numbers are:
LightCrafter's J7's trigger input and output pins are level translated or shifted to and from the I/O supply of circuits in the System board. Out of the factory, the output trigger signal is level shifted from the 1.8V I/O supply used by the System board FPGA to 3.3V. Below is a snapshot of the schematic of these circuits. U20 level shifts the trigger input. U23 level shifts the trigger output. Note that the supply on one side of these level shifters is tied to the internal 3.3V supply, while the other side is tied to 1.8V. The level shifter are open-drain outputs with internal 10Kohm pull-ups.
In this schematic, a resistor with a value of NA_0 indicates the resistor is not populated. A resistor value of 0 indicates that a zero ohm resistor is present.
If an external 5V trigger signal is desired, then the LightCrafter board must be modified to input an external supply and use that as the level shifter input voltage, as follows:
Then supply the external trigger voltage through Pin 1 of J7 (EXT_TRIG_VCC) and the external trigger through Pin 2 of J7 (TRIG_IN_CON).
Hi Pedro, I need some help interfacing a 5V MCU with the LghtCrafter Trigger inputs.
I would like to know if there is a simpler way of doing it, without modifying the system board.
I couldn´t find the R282 0ohm resistor. Where is it?
Unless you have a level shifter on the MCU to change the 5V signals to 3.3V, you will have to modify the board.
R282 is in the back of the SyStem Board (top board). It is in the group of three resistors that has a label next to the daughter card connector. It is between the daughtercard connector and screw hole, next to a ground test point. R282 is the middle resistor.
See the bottom left corner of this photo:
Pedro, I have a few quiestions about the trigger signals:
The threshold voltage for TRIG_IN_CON is handled by the TXS0101. From its data sheet, the Vil is 0.15V and Vih is Vcc - 0.2V where Vcc is the EXT_TRIG_VCC. Vcc can be anywhere between 2.3V to 5.5V.
You can power a circuit from EXT_TRIG_VCC. The amount of power is dependent on how much is consumed on the LightCrafter and the supply that is sourcing it. For instance, EXT_TRIG_VCC supports, 1.8V, 3.3V, and 5V options.
Note that the overall power budget is limited by the power supply into the LightCrafter system. This typically ranges between 2-3A. As you can see, there is enough current available on these supplies to power at least 100mA external circuit.
Thank you for the response Pedro.
I have a few more questions:
You will have to install 0 ohm resistor at R295, which is on the top of system board (above the J7 connector).
Here is the part number for 0 ohm resistor we used:
Digi-Key part number: P0.0AGCT-ND , Manufacture part number: ERJ-1GE0R00C
Could you please tell me how much current would the external circuit consume?
Please be aware of the current you can source from this pin. (Refer to Pedro's post above).
How would I be able to achieve a flexible output trigger configuration?
Industrial cameras currently use triggers of different voltage (e.g. Point Grey Flea 3V and IDS Imaging uEye 5V).
My idea would be to either move the zero-ohm resistor from R292 to R295, and source the appropriate trigger voltage from the camera itself, as most cameras provide some current at the right voltage.
The alternative would be a three position microswitch installed over R291, R292 and R293. Does anyone have experience with this and can you recommend a part that could be soldered directly onto these positions?
As most newer cameras use opto-isolated trigger ports, I wonder if one of these solutions offer an advantage in terms of current to drive the opto-isolated circuit? Also in the application note for "Imaging Source Cameras", it is suggested to output the trigger on pins 1 and 3, which reverses polarity. Does this mean more current?
Technical University of Denmark
We have tested the scenario mentioned in white paper i.e, externally triggering the LightCrafter by installing 0 ohm resistors at R292 and R295. But if your camera is capable of sourcing appropriate trigger voltage and current, you can apply idea 1 (U23 is an open-drain level shifter)
Unfortunately, I am not aware of a three position switch. LightCrafter E2E community might be able to help you.
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