DLPC3435: read Display Size (0x13) cmd returns zeros

Eriks Austrums

Part Number: DLPC3435
Other Parts Discussed in Thread: DLP2010LC

Hello,

Using programmers guide https://www.ti.com/lit/ug/dlpu020d/dlpu020d.pdf

I tried to read display size (0x13) and it returns all zeros, when I try to write the maximal display size of 854x480 as 0x5603e001 and try to read the size again It returns 0x03e00100.

Am I missing something? When I write this as External input image size (0x2E), It works and i can read the value back correctly .

What is the on reset value of this register? And does it affect the functions of the chip , if i leave the values as zeros?

Regards,

Eriks

over 5 years ago

0 Hirak Biswas over 5 years ago

TI__Genius 10925 points

Hi Eriks,

Welcome to TI E2E Forums! Kindly provide us some more info to understand your query better. Which EVM are you using? Are you using TI EVM or your own design?

Thanks & Regards,

Hirak.

0 Eriks Austrums over 5 years ago in reply to Hirak Biswas

Intellectual 675 points

Hello Hirak,

we are using our own design.

But does it really matter? The fact is that I cant set a register in DLPC3435.

Is there a sequence that i have to follow to write the Display Size register?

Regards,

Eriks

0 Hirak Biswas over 5 years ago in reply to Eriks Austrums

TI__Genius 10925 points

Hi Eriks,

Let me look into this and I will get back within a couple of days. Thanks for your patience!

0 Hirak Biswas over 5 years ago in reply to Hirak Biswas

TI__Genius 10925 points

Hi Eriks,

Could you please try reading/writing the Display Size register using the DLP2010LC GUI? This will confirm if the problem is in the FW.

0 Eriks Austrums over 5 years ago in reply to Hirak Biswas

Intellectual 675 points

Hi Hirak,

As we are using our own design, its not possible to write/read the Display size register using the GUI.

We are using our own implementation of the MSP430 code that reads/writes the Display Size register and others.

The fact is, that everything seemingly works, far as we can see. We can get the video stream out and change brightness and stuff.

The only problem as I can see is that we cant read/write to the Display Size register and it worries me because maybe later we will need this function and it won't work.

Any other tests or ideas of what could be the problem ?

Regards,

Eriks

0 Mark Locascio over 5 years ago in reply to Eriks Austrums

Prodigy 70 points

I see the same behavior with a DLP3433. I can send commands using the standard i2cget/i2cset utilities, but the 0x13 command always returns 0x00 0x00 0x00 0x00, even if I set the size using 0x12 first. I can set other properties, like the test pattern, but the image size command always stays zero.

-Mark

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

TI__Mastermind 28005 points

Mark,

It sounds like you are having issues with the I2CTools commands for read/write transactions.

There is a similar thread discussing the problem with potential solutions: https://e2e.ti.com/support/dlp/f/94/p/732735/2704927

Please review it and let us know if you have any questions on the same.

Regards,

Philippe Dollo

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

Prodigy 70 points

Hi Philippe,

Thank you for your response. I'm not sure that thread's solution is applicable here, though. In that thread, it is recommended to set the MSB of the write address to 1, which I do not currently do. However, many commands work without doing that (for example, changing the test pattern). In addition, that only makes sense if all write registers have addresses less than or equal to 0x7f, but several (like the DSI clock setting, 0xbd, and the DSI port enable, 0xd7) are using the MSB already.

So, to clarify, there are many values that I can set using the address as given in the DLP3433 documentation, without changing the MSB. However, this particular setting, the display size (0x12), does not get set.

Thanks,
-Mark

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

TI__Mastermind 28005 points

Mark,

There may be certain commands that ignore the read/write bit. You may want to try it both ways (with and without MSB bit) to see if your results differ.

Alternatively, you can also try sending the commands above using The LightCrafter GUI and probing the I2C bus to compare the data packets to yours sent through i2cset (https://www.ti.com/tool/DLPLCRD-GUI).

I hope this helps.

Regards,

Philippe Dollo

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

Prodigy 70 points

Hi Philippe,

I tried using 0x12 and 0x92. Afterward I read it back with 0x13, and I still just get zeros.

Thanks,
-Mark

0 Hirak Biswas over 5 years ago in reply to Mark Locascio

TI__Genius 10925 points

Hi Mark,

Please provide us some more time to look at the possible reasons for this issue. We will get back within 2 days.

0 Austin Snyder over 5 years ago in reply to Hirak Biswas

TI__Genius 12785 points

Hello Mark and Eriks,

The problem you are running into is likely due to an error in the programmer's guide. In place of sending and receiving 4 bytes, you should be sending and receiving 8 bytes to adjust and the display size.

Pages 27 and 28 of the DLPC3470 and DLPC3478 Programmer's Guide give the correct format of the commands to be sent to adjust and read the display size.

We apologize for the delay in getting this information to you.

Kind regards,

Austin

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DLPC3435: read Display Size (0x13) cmd returns zeros