DLPC3478: DLPC3478 External Pattern Streaming Mode

Masayuki Iwata

Part Number: DLPC3478

Hello,

I have developed a projector board using DLPC3478.
It operates in external pattern streaming mode that transfers data from FPGA to DLPC3478.

As shown in the figure, when one frame is transferred and then the next frame is transferred after a while (approximately 10 to 15 seconds), the previous frame is projected from DLPC3478.
At this time, granular noise is superimposed on the entire projection data.
The longer the interval, the greater the amount of noise.
Please tell me the reason.
Has the DLPC internal memory been refreshed correctly?
Also, if this behavior is a chip specification, what is the allowable interval time?

Regards, Masa

over 4 years ago

0 Kyle Rakos over 4 years ago

TI__Mastermind 20045 points

Hello Masayuki,

Taking a look at section 7.2 of the DLPC3478 datasheet the minimum input frame rate is 10 Hz. Therefore, I do not think you can wait that long to input the next frame. Additionally, the controller expects a periodic input. Would you be able to continuously input the first image for the 10 - 15 seconds until the next frame appears? If so, perhaps this could work? Or are you projecting dark time for those 10 - 15 seconds?

Thanks,

Kyle

0 Masayuki Iwata over 4 years ago in reply to Kyle Rakos

Intellectual 710 points

Hello Kyle,

This response is disappointing because we received a response from e2e.ti.com/.../3148312 that Vsync can be delayed.
When I transferred frames in succession, there was no noise except for the first frame.

Regards, Masa

0 Kyle Rakos over 4 years ago in reply to Masayuki Iwata

TI__Mastermind 20045 points

Hello Masa,

Sorry about any confusion. I believe we are still trying to figure out if this can be supported or not. Could you please help by answering if you were you able try the image freeze command as suggested in that post? Or is this attempted without the image freeze command?

Thanks,

Kyle

0 Masayuki Iwata over 4 years ago in reply to Kyle Rakos

Intellectual 710 points

Hi Kyle,

I have not tried the image freeze command.
Teach me Please. Is it OK to execute the image freeze command as shown in the figure?
I want to try it.

Regards, Masa

0 Philippe Dollo over 4 years ago in reply to Masayuki Iwata

TI__Mastermind 28005 points

Masa,

If you are able to hold the VSYNC stable (no edges during the freeze duration), you should technically be able to retain the parallel data that you received (frame N+1) and display it after the image freeze turns OFF. If any VSYNCs trigger, however, that data will be written to the frame buffer and lost.

Regards,

Philippe Dollo

0 Masayuki Iwata over 4 years ago in reply to Philippe Dollo

Intellectual 710 points

Hi Philippe,

I'm sorry, I don't understand your answer very much.
I'll hope that my figure timing is correct.
In short, can the noise eliminated in the way shown figure?
(During freeze, VSYNC is not input and data enable is not enabled).

Regards, Masa

0 Vivek Thakur over 4 years ago in reply to Masayuki Iwata

TI__Mastermind 22880 points

Hello Masa-san,

Do you still need help with this problem?

regards,

Vivek

0 Masayuki Iwata over 4 years ago in reply to Vivek Thakur

Intellectual 710 points

Hi Vivek,

We haven't tried the freeze command yet.
If we need more help, we will ask again at the time.

Please close this thread.
Thank you.

Regards, Masa

0 Vivek Thakur over 4 years ago in reply to Masayuki Iwata

TI__Mastermind 22880 points

Masa-san,

Thank you.

regards,

Vivek

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DLPC3478: DLPC3478 External Pattern Streaming Mode