TVP5150APBS Active Video Cropping

Hi JEB,

Are you using the TVP5150A or TVP5150AM1?  The TVP5150AM1 has more recent firmware and the TVP5150A is NRND.   We will check to see if this bug existed in the TVP5150A and get back to you.

Hi JEB,

The negative values for AVID are used to expand out the number of active pixels, or in other words increase the number of active pixels from 720 to a greater number.

Part of the problem you are seeing is most likely due to an error in the datasheet and a bug in our Firmware.  The text for the Vertical Blanking Start and Stop Registers (page 2-29) should be as follows:

Vertical blanking (VBLK) start:

0111 1111 = 127 lines after start of vertical blanking interval

0000 0001 = 1 line after start of vertical blanking interval

0000 0000 = Same time as start of vertical blanking interval (default) (see Figure 2−2)

1111 1111 = 1 line before start of vertical blanking interval

1000 0000 = 128 lines before start of vertical blanking interval
Vertical blanking (VBLK) stop:

0111 1111 = 127 lines after stop of vertical blanking interval

0000 0001 = 1 line after stop of vertical blanking interval

0000 0000 = Same time as stop of vertical blanking interval (default) (see Figure 2−2)

1111 1111 = 1 line before stop of vertical blanking interval

1000 0000 = 128 lines before stop of vertical blanking interval

The Active Video Cropping Stop Pixel registers are not working properly.  The Active Video Cropping Start Pixel registers are working properly.  Is it OK for you to crop all of the pixels from the beginning of the line, rather than some from the beginning and some at the end?  If not, then we can work with you on a work-around by writing to the TVP5150A's indirect registers.  The example below crops all of the pixels from the beginning of the line.

Example - To crop your image from 720x243 to 704x240, please follow these steps.  We verified this in the lab.

1.     Write a “1” to bit 2 of register 12h.

2.     Write 0x01 to register 19h.  This will crop the first line.

3.     Write 0xFE to register 18h.  This will crop the last 2 lines.  Note: The 243 lines are actually 242½ lines, so dropping 3 lines would give you 239½ lines.  You can write 0xFF if you want to only drop the last line, giving you 240½ lines.

4.     Write 0x04 to register 11h.  This will crop the first 16 pixels of the line, taking you from 720 to 704.

TVP5150A.  Understood that this is NRND.  This is an existing design that we are still shipping.

http://focus.ti.com/docs/prod/folders/print/tvp5150a.html

I want to crop pixels at just the end of the line.  I would prefer not having to crop pixels at the beginning of the line.  If you have a work around where we can only crop pixels at the end of the line, I would appreciate having that information if it isn't too much trouble.

Thanks for the support.

Hi JEB,

Below is the address and default value for AVID_START and AVID_STOP.  This work around requires these registers reload every time the system power up and standard change.

Indirect Register              Address              NTSC default            PAL default

AVID_START                      34Bh                               8Bh                        93h

AVID_STOP                        34Ch                               01h                        03h

Attached is the document show you how to read/write to these indirect registers.

Regards,

Viet

The attached document was for the TVP5150AM1.  We are not using the TVP5150AM1.  We are using the TVP5150A.  Do those instructions apply to the TVP5150A as well?

JEB,

This app note is apply to TVP5150A and TVP5150AM1.  Sorry for the confusion.

Regards,

Viet

Hey Viet,

Thanks for the help yesterday.  Using the indirect registers for the horizontal AVID cropping did work for me. 

We use embedded syncs.  When using the horizontal AVID cropping registers, the location of the embedded syncs DO change which is what we want.  However, using the AVID vertical cropping registers (18h and 19h), the line number that the V bit transitions in the embedded sync does not appear to change, hence I can't crop active lines using those registers from what I observed when using embedded syncs.  Is there a way to change the line numbers where the V bit transitions off/on in the embedded sync so that we end up with the same effect that we achieve with horizontal AVID cropping i.e. the vertical lines can be cropped using embedded syncs?

Hi JEB,

Below is the address and default value for AVID_FIELD_START and AVID_FIELD_STOP.  This work around requires these registers reload every time the system power up and standard change.

Indirect Register                            Address              NTSC default            PAL default

AVID_FIELD1_START                      229h                            13h                        24h

AVID_FIELD2_START                      22Ah                            13h                        25h

AVID_FIELD1_STOP                        22Bh                            03h                        02h

AVID_FIELD2_STOP                        22Ch                            02h                        02h

Please give it a try to see if they work for you.

Regards,

Viet

OK thanks.

Is it possible to blank pixels and/or lines without changing the position of the syncs?

JEB,

The TVP5150 can blank the whole screen but could not change to blank pixels and/or lines.

Regards,

Viet

Can you give me a little more insight on the range of allowable values for each register and what the values mean?

Hello JEB,

Sorry for a delay but those registers are for active field start and stop.  The range for each field in NTSC is 1 to 525/2 and PAL is 1 to 625/2.

Regards,

Viet

Hey Viet,

Once again, thanks for the help.  Ideally what I would like to do is control for each field:

The line number where the V bit in the embedded sync transitions to 1,

The line number where the V bit in the embedded sync transitions to 0,

The line number where the F bit in the embedded sync toggles. 

Is it possible to control those, and if so, can you give me those registers.