Next pattern via software trigger

Hello Sanjeev,

thank you. I already used the workaround, it's ok for me so far.

Regards

Ole

I'm using this workaround too, but I'm finding it extremely unsatisfactory.  It results in a delay between each pattern that slows things down considerably.  The API calls also fail with some frequency, especially LCR_ValidatePatLutData(), in which case I have to retry them, slowing things down even further.

Is there a way to just load splash images, but with all image processing disabled?  That would at least avoid resetting the pattern lut on every image.

Thanks,

Benedict Brown

Hello Benedict,

Another possibility you could look into is creating a pseudo software trigger with the DLPC350 GPIO and input triggers. You could  connect the GPIO to the input triggers and then control the triggering via the GPIO control over software without needed to resend the LUTs every time.

Please note that I haven't verified this operation, but in theory it should work.

Best regards,

Blair

Thank you, I'll try this.  It seems like a simpler configuration than building a separate trigger.

If it's possible to introduce the ability to advance the pattern (or even to jump to an arbitrary pattern) via a firmware update, I think this would be a very nice feature to have for structured scanning applications. 

After looking into this further, I'm not sure how to connect the GPIO to the input triggers.  I can find the documentation for the controller pinouts, but not for the system board terminals on the 4500.  (I do see the pinout mapping for connecting the PandaBoard, but it only seems to document the pins that the PandaBoard actually uses.)

Is there complete documentation somewhere of these pinouts, or can you give me directions along the lines of "connect pin X of jumper A to pin Y of jumper B to tie GPIO Z to trigger_in_1"?  If I read the documentation correctly, I need to connect two GPIO signals as outputs to trigger_in_1 and trigger_in_2.

Thank you,

Benedict Brown

Hello Benedict,

The pinouts listed in section 6.1.1 "DLP LightCrafter 4500 to PandaBoard Interface" in the DLP LightCrafter 4500 User's Guide show the Pandaboard pinout on the left side of tables and the LightCrafter 4500 pinout on the right side.

Table 6-2 shows that the SYS_TRIGGER_IN_1 is on connector J3 pin 10 and SYS_TRIGGER_IN_2 is on connector J3 pin 12.

You'll need to set the SYS_TRIGGER_SEL pin on J6 to 1.8V to enable the level shifter between the DLPC350 and the system connectors.

After the level shifters are enabled, you are correct in connecting two of the GPIO to the trigger inputs. Let me know if there's anything else I can help with.

Best regards,

Blair

Thanks Blair.  The confirmation of these things is very helpful.  But I'm afraid the part I'm least clear on is where the GPIO outputs are.  Is that the JTAG connector for the DLPC350?

As I'm sure you've figured out, I'm a software person, and fiddle with hardware as little as possible.  But I will have someone more versed with this to help me connect everything up.  In the meantime, using LoadSplash to display images is working well, even for phase patterns.  It doesn't seem to give as much light as pattern mode, but the speed is fine and it seems to be photometrically linear.

Benedict

Hello Benedict,

The GPIO for the DLPC350 are on the J6 connector. Running the EVM in video mode causes the LEDs to sequence one after the other which leads to a lower brightness. Pattern sequence mode can turn all LEDs on simultaneously, which gives the brighter output.

Best regards,

Blair 

Don't I have to supply a 1.8V to Pin 1 of J3 or pin 2 of J4 in order to power the U9 so that I am able to use the GPIOs (and trigger_in)?

Hi John,

Are you using PandaBoard to drive the trigger input signals? If not you can use J11 directly.

If you are using the Panda Board you can refer to the 6.1.1 DLP LightCrafter 4500 to PandaBoard Interface section in the EVM user's guide.

Regards,
Sanjeev

Hi Sanjeev,

I was actually thinking of using the following approach:

PandaBoard J6(pin 10 - GPO 12) -> PandaBoard J3(pin 10 - SYS_TRIG_IN_1)

PandaBoard J6(pin 9 - GPO 11) -> PandaBoard J6(pin 19 - SYS_TRIGGER_SEL)

 This way I could control the GPO 12 and 11 though my software and trigger the frame change using the USB connection alone which will allow me to not use the J11 trigger. But in any case; either to use the GPO available with SYS_TRIG_IN_1 (on J3) or TRIG_IN_1 (on J11), I still need to use two of the GPO 0,2,11,12.

But according to the schematics I observed, it would seem that I need to connect a 1.8V source to PandaBoard J3(pin 1 - EXT1V8) in order to power the SN74AVC8T245's VCCB. This is my understanding. I am wondering three things actually:

1) Do I need to connect a 1.8V source into the PandaBoard J3(pin 1 - EXT1V8)?  

2)If the answer to Q1 is 'Yes', is it safe to use the PandaBoard J10(1.8V source) to directly connect to PandaBoard J3(pin 1 - EXT1V8)?  

and lastly 3) If the answer to Q1 is Yes,  why wasn't 1.8V connected to J3 already in the design?

Thank you in advance.

#1. yes if you are using the signals on the J3.

#2. I believe your intention is not to use the PandaBoard rather use GPIO from LCr4500 EVM itself as trigger signals. So answer is Yes.

#3. All the signals are 1.8V coming PandaBoard ; so the 1.8V is reference from the PandaBoard, so when PandaBoard is connected and operational it will turn the circuit on.

Thank you for the answer Sanjeev. Actually I am trying to use a different product called Pro 4500. I discuss it in terms of the PandaBoard because I thought may be it is not that popular. So yeah, I was trying to use the J33A and J33B on Pro 4500 which is equivalent to J3 and J4 on PandaBoard respectively.

So what you mean is that connecting 1.8V to Pin 1 of J3 (on PandaBoard) using a jumper wire is absolutely necessary and I cannot avoid that if I wanted to use the GPIO 0, 2, 11 and 12? There is no work around that is it?

My comments with reference to LightCrafter 4500 EVM, yes, there is no workaround.

Regards,
Sanjeev

Thank you Sanjeev. I guess I will have to go with a PandaBoard then.