DLPDLCR2000EVM: EVM with Raspberry Pi3 B+ Screen Flicker / Glitch Issue

GOPINATHAN M

Part Number: DLPDLCR2000EVM
Other Parts Discussed in Thread: DLP2000, DLPC2607,

When I connected Raspberry Pi 3B+ with EVM 2000, I can able to see the desktop, but the screen is flickering / glitch. I saw a related article about changing the GND pin from EVM to Rpi3 pin 6 (GND).

https://e2e.ti.com/support/dlp/f/94/t/700072

I don't understand which GND pin from EVM? Please provide the exact pin number. There are 5 GND pins in EVM P2 side.

over 5 years ago

0 Kyle Rakos over 5 years ago

TI__Mastermind 20045 points

Hello Gopinathan,

The ground of the Pi should be connected to the ground of the EVM so the signals have a common ground. It doesn't matter which specific ground pin on the EVM is used as all of the grounds are electrically the same.

Thanks,

Kyle

0 GOPINATHAN M over 5 years ago in reply to Kyle Rakos

Prodigy 200 points

Thank you Kyle.

Is ang other troubleshooting guide to solve the screen flickering issue ?

This is annoying for me. Initially I tried with BeagleBond black, I felt the performance is not good, unable to play video or browser smoothly.

Later I integrated with Pi 4B, but the display never turned ON, i2c detects on address 7 instead of 3.

Again I tried with Pi3B+, now everything is Ok, except the flickering issue.

0 Kyle Rakos over 5 years ago in reply to GOPINATHAN M

TI__Mastermind 20045 points

Hello Gopinathan,

Did you attach the grounds of the two units? Additionally, if a different address is detected it should be simply changeable by software.

Thanks,
Kyle

0 Kyle Rakos over 5 years ago in reply to Kyle Rakos

TI__Mastermind 20045 points

Hi Gopinathan,

If you still need assistance please let me know. For now I will mark this thread resolved.

Thanks,
Kyle

0 Maxim Khazanov over 5 years ago in reply to Kyle Rakos

Prodigy 180 points

Hello, I think I have the same issue:

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

The issue above is very likely due to timing issue between the Raspberry Pi and BBB. The two easiest ways to resolve this:

> Relax video timings in the config.txt of Raspberry Pi

> Use an adapter board (such that this one from MickMake https://www.tindie.com/products/mickmake/pi-projector/) or equivalent to interface the systems without using jumpers

If you cannot do the above, you should check your jumpers and try to ensure they are all as close in length as possible to avoid timing problem.

I hope this helps.

Best Regards,

Philippe Dollo

0 GOPINATHAN M over 5 years ago in reply to Philippe Dollo

Prodigy 200 points

Thanks for the update.

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Thank you for reply, I checked the timings (made according to w*h*60 fixed the glitch)

But I'm getting this result with 854x480 resolution. With 720x480 it works with 0x0c to 0x09 at i2cset, but not using full width.

According to DLPC2601 Programmer's guide, it supposed to be 0x0c set to 0x19 for 854x480 but it gives something like 640x480 and strangely works with 0x13, but gives this issue from screenshot.

I'm looking forward for your recommendations

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

I've personally tested this behavior on a Raspberry Pi and produced a similar result as you.

In this case, choosing the incorrect resolution (on purpose) does appear to somehow accommodate the problems introduced by using jumpers for the Raspberry Pi connection. However, this does not resolve the root cause.

Changing the setup to use a PCB adapter along with a GPIO ribbon cable results in a much more stable connection. For further optimization, I also recommend adjusting the GPIO drive strength on your output:

> gpio drive 0 #

Where # is the desired drive strength (from 0 to 7). I hope this helps.

Regards,

Philippe Dollo

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Philippe, thanks for your reply.

I didn't expect any more answers in this tread so I opened a new one: https://e2e.ti.com/support/dlp/f/94/p/850392/3155530#3155530 with my own reply at the end of how I fixed that.

May I ask here if you know something about color banding issues?

Regards,

Maxim

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

Which color banding behavior are you referring to?

Thanks,

Philippe Dollo

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Philippe,

This one (using rgb666 as output and rgb888 as input at dlp2000)

So I thought it could happen because of missing colors between rgb666 and 888. Then I tried to output rgb888 with same result:

I even tried to swap rgb to bgr and got same red lines:

I can't understand where it come from...

I also saw that it is possible to set input to be rgb666 on dlpc2607 with i2c 0x0D set to 1, which gives me mixed colors result. Is that a different pinout for RGB666? Where can I find it?

24bit and 16bit info and bbb are easy to find, but no not 18bit.

I'm going to check rgb565 now...

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

On RGB666 and RGB888, you should not get any banding as long as you have everything hooked up properly. You might actually see some banding with RGB565 since the code transitions won't be even anymore (such as on the white ramp).

The pin mappings on both the Raspberry Pi AND the DLPC2607 (the controller on the DLP2000 EVM) are different for each pin mapping. For the DLPC2607, you should check section 7.3.1 of the DLPC2607 datasheet:

http://www.ti.com/lit/ds/dlps030e/dlps030e.pdf

Meanwhile, you should check this page for the Raspberry Pi:

https://www.raspberrypi.org/documentation/hardware/raspberrypi/dpi/README.md

For the PI, you need to modify the hardware connections as well as the "mode" setting in config.txt. For the DLPC2607, you do need to send a command (0x0D) to change the image format.

I hope this helps. Let me know if you have further issues.

Regards,

Philippe Dollo

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Thank you Philippe,

May I ask you if I'm right with:

according to http://www.ti.com/lit/ds/dlps030e/dlps030e.pdf

connections (I took from https://elinux.org/24bit_LCD_for_BBB) should be updated:

(*not talking about rgb or bgr, numbers are from raspberry color assignments, mode 5 rgb666)

or may be this one:

0 Maxim Khazanov over 5 years ago in reply to Maxim Khazanov

Prodigy 180 points

Tried all of that with no luck... Of cause setting 0x0D to 0x01 (RGB666).

I'm really looking forward to your reply here and color mapping on GPIO on DLP2000EVM

I'm using this map:

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

The mapping used in the "updated" side of the first image looks like it should be correct for this RGB666 configuration.

Are you properly modifying the image format settings on the Pi's side? Furthermore, have you verified that you are getting signal (such as Vsync) from the Raspberry Pi?

Regards,

Philippe Dollo

0 Philippe Dollo over 5 years ago in reply to Philippe Dollo

TI__Mastermind 28005 points

Maxim,

Any updates on this issue? Let me know if you need further assistance.

Regards,

Philippe Dollo

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Philippe,

No, same banding issue. Checked all variants, seems like settings from "current" on the picture is the one according to http://frederickvandenbosch.be/?p=2948. Going to change cables now, will reply after.

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

Thanks for the update. If you continue having issues, I also recommend reviewing your GPIO drive settings. You can adjust the GPIO drive strength per the example command:

> sudo gpio drive 0 #

Where # is the drive strength (from 0 to 7).

Regards,
Philippe Dollo

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Philippe, I tried all variants of gpio drive settings (works without glitch if above 0),

but still I cant' get rid of color banding:

0 Philippe Dollo over 5 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

What color space are you using in your latest setup?

The most likely issue here is that data is getting lost somewhere in the pipeline, or expected but never received. In this case, I recommend you start from scratch and use a full width video output (RGB888) into the DLPDLCR2000EVM. You can configure the EVM before you attach the video input in this case.

From there, you should use your gradient output and test every bit. I also recommend you compare this output to the internal white ramp test pattern. From here you should be able to narrow down which bits aren't making it across.

I hope this helps.

Regards,

Philippe Dollo

0 Maxim Khazanov over 5 years ago in reply to Philippe Dollo

Prodigy 180 points

Philippe,

Color space I'm using is RGB888 from RPi's 18 pins, skipping first two bits. Color selftest by the DLPDLCR2000EVM is fine, even the gray ramp on splash screen is ok.

I'm looking now for a way for testing every bit, as you say. Do you have any recommendations?

Regards,

Maxim

0 Vivek Thakur over 4 years ago in reply to Maxim Khazanov

TI__Mastermind 23070 points

Hi Maxim,

Do you still need help with this issue?

regards,

Vivek

0 Maxim Khazanov over 4 years ago in reply to Vivek Thakur

Prodigy 180 points

Hi Vivek,

Yes, absolutely. I think I checked everything and I am at the same position of screen banding now...

regards,

Maxim

0 Vivek Thakur over 4 years ago in reply to Maxim Khazanov

TI__Mastermind 23070 points

Hello Maxim,

I appreciate update. Our team member will get back to you on this issue.

The response will slow and may take some time. Please understand that it is Holiday period.

Thank you for your understanding.

regards,

Vivek

0 Philippe Dollo over 4 years ago in reply to Vivek Thakur

TI__Mastermind 28005 points

Maxim,

"Color space I'm using is RGB888 from RPi's 18 pins, skipping first two bits. Color selftest by the DLPDLCR2000EVM is fine, even the gray ramp on splash screen is ok."

Can you elaborate on which "first two bits" you are skipping?

Regards,

Philippe

0 Maxim Khazanov over 4 years ago in reply to Philippe Dollo

Prodigy 180 points

Philippe,

My connections are similar to http://frederickvandenbosch.be/?p=2948

so I'm skipping Data18-23

Regards,

Maxim

0 Philippe Dollo over 4 years ago in reply to Maxim Khazanov

TI__Mastermind 28005 points

Maxim,

Thanks for your explanation. if you are using RGB666 mapping in hardware, have you tried also setting the Raspberry Pi to output RGB666 in software?

This may help you ensure your test images appear linear on the output. Since the internal test patterns on the DLP chipset are all clean, this shows that the issue lies either with the Raspberry Pi's configuration or the video interface between the Pi and the DLPC2607.

Regards,

Philippe Dollo

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DLPDLCR2000EVM: EVM with Raspberry Pi3 B+ Screen Flicker / Glitch Issue