TVP5154 image too bright

Eric Lammerts

Other Parts Discussed in Thread: TVP5154

Hi,

sometimes the picture I get from the TVP5154 is way too bright. When I read register 0x8a (AGC) I will see values >100 (I've seen 151, 251, etc). When the picture is OK it's usually 24 or so. The input circuit is as recommended (37R4 + 37R4 divider, followed by 100n cap). The input signal is PAL and comes from either a Sony EVI-D70P or Dallmeier DF3000AS so should be fine (I've seen it happen with both cameras).

When this happens I can fix it by powering down and up (-> write 3 to register 2, wait 1 second, write 2 to register 2).

Settings:

reg 0=0x00

reg 2=0x02

reg 3=0x0d

reg 5=0x08

reg 8=0x40

reg 0xd=0x07

reg 0x28=0x04

I have the luma peak processing disabled because otherwise the picture starts to flicker after a while (sometimes).

Readback from status registers when I was seeing the problem:

reg 0x88=0x6e

reg 0x89=0x38

reg 0x8a=0x97

reg 0x8b=0x6a

reg 0x8c=0x83

Is it normal for the AGC to be "frozen" (bit 3 of reg 0x89)? Because this bit seems to be always set, even if the picture is fine.

regards,

Eric

over 15 years ago

0 Viet Dinh over 15 years ago

TI__Genius 15310 points

Hello Eric,

You are running with AGC and ALC disabled. Please change the register 00h to 15h which will enable AGC and ALC. The ALC (bit 3 and 2) is required to be enabled to get the TVP5154 work properly.

Regards,

Viet

0 Eric Lammerts over 15 years ago in reply to Viet Dinh

Prodigy 40 points

Hi Viet,

thanks for the quick reply. In the datasheet I see that 15h is the default value for register 01h (I assume you mean register 01h not 00h). And when I read register 01h back I get 15h. Do you recommend programming all registers even if the defaults are fine for my application? (right I only program the registers that need values that are different from the defaults)

regards,

Eric

0 Viet Dinh over 15 years ago in reply to Eric Lammerts

TI__Genius 15310 points

Hello Eric,

I am sorry, it is my mistake. The register 00h should be 0 for CVBS1 so you are right. The register 01h supposes to be 15h so you are OK. You donot need to programming all the registers if it is same as defaults. Can you also try to disable white peak to see if it helps (set bit 3 of register 02h).

Sorry Eric, please ignore the patch I sent earlier. That patch is from other device, not TVP5154.

Regards,

Viet

P5150A_048CAA.zip

0 Eric Lammerts over 15 years ago in reply to Viet Dinh

Prodigy 40 points

Hi Viet,

does a patch exist for the TVP5154?

The chip rom version is reg 82h=02h, reg 83h=00h

thanks,

Eric

0 Viet Dinh over 15 years ago in reply to Eric Lammerts

TI__Genius 15310 points

Hi Eric,

Yes, we do have patch for TVP5154 which fix the problem the brightness need to be change after contrast get modify but not the one you seen. We havenot seen or get any reported from the field with the image too bright.

Regards,

Viet

0 Eric Lammerts over 15 years ago in reply to Viet Dinh

Prodigy 40 points

Hi Viet,

should I give that patch a try? Can I download it somewhere?

thanks,

Eric

0 Viet Dinh over 15 years ago in reply to Eric Lammerts

TI__Genius 15310 points

Hello Eric,

Attached is patch version v0202. Please give is a try to see if it helps.

Regards,

Viet

v0202.zip

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TVP5154 image too bright