AM625: Signal format at DSS parallel interface (DISPC VP2)

Expert 2851 points

Tool/software:

May I have qustion about AM625x DISPC VP2?

I think this port supporting 24, 18,...-bit parallel display interface.

Question1

If useing 24-bit mode, the LSB is VOUT1_DATA[0]? or VOUT1_DATA[23]?

Question2

If set 24-bit mode, and not use low 6-bit, it be allowed?

Processor side set as 24-bit mode, but Display side use 18-bit.

Question3

If useing 18-bit mode, it may be unconnected DATA[23:18].

Is this mean DATA[23:18] was LSB in 24-bit mode? (signal is same as 24bit mode?)

Or hardware will shift 6-bit such as DATA[23:6](@24-bit mode) shift to DATA[18:0] ?

Thanks,

7 months ago

0 Kallikuppa Sreenivasa 7 months ago

TI__Guru**** 168764 points

Hello GR

Thank you for the query.

I am reviewing the inputs.

One quick note is the 24 bit is a combination of 8 bits X RGB.

I am not sure what you mean by LSB or MSB.

Please elaborate.

Can you please share the use case for the queries to support better.

Regards,

Sreenivasa

0 GR 7 months ago in reply to Kallikuppa Sreenivasa

Expert 2851 points

Hi Sreenivasa,

Thanks for your supporting.

I missread customer's question.

Correct question is this.

LSB is Least Significant Bit of the data.

If I want to down scale the data resolution, It need to discard least bit.

Best regards,

+1 Kallikuppa Sreenivasa 7 months ago in reply to GR

TI__Guru**** 168764 points

Hello GR,

Thank you.

GR said:
LSB is Least Significant Bit of the data.

data 0 is B0

data 8 for G0

Data 16 for R0

(+) [FAQ] AM625 / AM623 / AM625SIP / AM625-Q1 Custom board hardware design – Display Parallel Interface (DPI) 24-bit RGB - Processors forum - Processors - TI E2E support forums

GR said:
If I want to down scale the data resolution, It need to discard least bit.

I assume 24 bit connect to 18 bit. discarding the least bit would minimize the effect on performance.

Regards,

Sreenivasa

0 GR 7 months ago in reply to Kallikuppa Sreenivasa

Expert 2851 points

Hi Sreenivasa,

Kallikuppa Sreenivasa said:
GR said:
LSB is Least Significant Bit of the data.

data 0 is B0

data 8 for G0

Data 16 for R0

Do you mean B0 is LSB of blue data?

Rarely, there is semiconductor that maybe B0 is MSB for blue.

So I want to check it.

e.g. Lattice bridge IC

https://www.latticesemi.com/view_document?document_id=51675

Thanks,

0 Kallikuppa Sreenivasa 7 months ago in reply to GR

TI__Guru**** 168764 points

Hello GR,

Thank you.

Did the FAQ not address the query?

Please refer below section of the FAQ

12.9.1.2.1.1 Pixel Data Formats

The below FAQ has links to key collaterals including the TRM

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1183910/faq-am625-custom-board-hardware-design-collaterals-to-get-started

Regards,

Sreenivasa

0 GR 7 months ago in reply to Kallikuppa Sreenivasa

Expert 2851 points

Hello Sreenivasa,

I saw the TRM 12.9.1.2.1.1 Pixel Data Formats.

I found DATA[0] is B0(blue data 0) in RGB mode.

But I can not find "B0" will be LSB or MSB for blue data.

Normally, B0(blue bit-0) would indicate LSB, but the customer wants to make sure this is correct, just in case.

And the E2E link written information for RGB data format?

Best regards,

+1 Kallikuppa Sreenivasa 7 months ago in reply to GR

TI__Guru**** 168764 points

Hello GR,

Thank you.

GR said:
Normally, B0(blue bit-0) would indicate LSB

This is correct.

I suspect this is standard LCD terminology.

Regards,

Sreenivasa

0 GR 7 months ago in reply to Kallikuppa Sreenivasa

Expert 2851 points

Hello Sreenivasa,

Thank you!

I understand.

Best regards,

+1 Kallikuppa Sreenivasa 7 months ago in reply to GR

TI__Guru**** 168764 points

Hello GR,

Thank you for the note.

Regards,

Sreenivasa