This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DLP3010EVM-LC: DLP3010EVM only provide 3.26V trigger output signal. Not enough to trigger the camera

Part Number: DLP3010EVM-LC
Other Parts Discussed in Thread: SN74LV4T125

Hello, I was trying to trigger my camera using DLP3010EVM trigger output. I used J4 pin (4th pin) and ground for trigger output. However, the output voltage is on 3.26V and my camera require 3.3V. So it does not work. I tested my camera using a higher voltage source, and it worked. That means my camera is fine. It is just the output voltage is not enough. Any suggestions? Thank you guys!

  • Hello Bing,

    Welcome to DLP forum and thank you for your interest in DLP technology.  

    Typically, camera trigger level have small margin. The  3.26 V is close for 3.3V trigger level.  You may to want reconfirm the trigger level for camera.

    If the camera trigger level is higher then you need to add level shiftier circuitry.

    How did measure the output voltage level of the EVM trigger? Was camera connected or open? How does signal trace looks?

    regards,

    Vivek

  • Bin Yang,

    Some industrial cameras have optocoupled trigger inputs that require relatively high current (5-10mA) to operate the trigger signal.  If you are using one of these cameras then you may need to add an external buffer to drive the camera trigger because the trigger outputs on the DLP3010EVM-LC (while working very well for CMOS signaling) cannot supply enough current for optocouplers.  

    If you are sure that you just need a slightly higher voltage on the trigger output then you should be able to get it with the following hack (which may not meet with TI's official approval).  Remove the jumper on J11 on the main board--very important to do this--and apply an external voltage to J4 pin 8 on the display board. This voltage must not exceed 3.6V or you will risk damaging the output buffers on both the main and display boards.  You may have already tried this, but it is a simple way to get the trigger output voltage up to as much as 3.6V to see if that will drive your camera from the DLP3010EVM-LC.

  • Hi Layne, thank you for your reply! I think you probably are right about the current required. The camera require at least 3.5mA in additional to 3.3V.  Could you provide a bit more information about how I can achieve that requirement? You mentioned external buffer, however I don't have a strong background in electronics. With more information, I can seek help in my department. Thank you very much!

  • Hi Vivek, thank you for your reply! I think the issue might to related to that my camera requires 3.5mA to function properly. This could be the real source of the issue as Layne Jenkins mentioned in reply to my post. 

  • The fastest way to get up and running if you're only using this for R&D purposes is to use a plug-in breadboard and a buffer IC in a DIP package.  The Texas Instruments SN74LVC245 has plenty of drive current at 3.3V and is still available from distributors in DIP.  Most industrial cameras will accept higher-voltage inputs so if you can find a level translator with sufficient drive and in a DIP package then you could step up the output to 5V and increase your noise margin while still being able to prototype quickly...but I couldn't find anything appropriate with a quick search.

    Keynote Photonics has a product similar to the TI DLP3010EVM-LC but with optocoupled outputs to enable high voltage, high current interfacing to industrial cameras.  If later you are looking for a production-ready solution using the same TI chipset then please feel free to take a look at Keynote's LC3010 structured light projector.  

  • Hi Layne, again, thank you for your reply. I wish I knew there was an updated version.. I just took a look and it seems exactly what I need. For our future applications, we definitely will consider Keynote's LC3010. 

    I just wanted to confirm that with 3.26V input, the SN74LVC245 can output 3.3V with sufficient current (>=3.5mA) to trigger a camera, correct? Thanks again for your time answering my questions!

  • Actually the output voltage may be a little low on the 74LVC245.  If your camera can take 5V signaling then it would be better to use the SN74LV4T125 which you can power from the 5V on the display board J4 pin 2.  The only problem is the SN74LV4T125 is not available in a DIP package for easy prototyping but you can order the TSSOP version package and solder it to a DIP adapter, like DigiKey part number 1528-1069-ND.  Then you can plug it into a breadboard for easy wiring.  

  • Hi Layne, thank you for your detailed reply. I will try SN74LV4T125 and report back if it works. I guess there are users might encounter this similar issue.

  • Hello Layne,

    Thank you. Appreciate your help on this issue.

    regards,

    Vivek