TVP5150AM1: How to setup 7.5IRE ?

Just curious... are you trying to decode a non-standard video signal?

The TVP will usually detect the correct video format and automatically adjust the digital output range to correspond to the source analog video format.

Usually the only time you need to force the pedestal setting is if you have a non-standard signal.

How are you determining that the pedestal setting is having no effect?

BR,

Steve

Hi Steve,

We use the pattern generator ASTRO-VG872C and the SMPTE color bar as test pattern to check the black level. The three dark bar should be superdark(0 IRE), dark(7.5IRE) and gray.

So, if we use NTSC-M and set pedestal(7.5IRE), we should only see two dark bar at lower right.

We always see the three bar whatever the register 07h[6] is one or zero, so it seems the registers is useless.

Could you give us some suggestions? or how to debug the issue?

Thank you,
BR,
Maxli

Do the digital video data values change when you toggle the pedestal register?

BR,
Steve

Hi Steve,

We use the NTSC-M and full black screen to read the digital data values of YUV422.
They are alwyas the "19 80 20 80" when we toggle the pedestal register! (0x60 switch to 0x40 and switch to 0x60)
We also write the pedestal register then read back to check the value.

We dump all the TVP reigsters for you.
"r" means the reserved and skip to read it.
=======================================================================
- : 0 1 2 3 4 5 6 7 8 9 a b c d e f
0 : 0 15 0 6d 0 0 10 40 0 80 80 0 80 47 0 a
10 : 0 0 0 0 0 25 5f 80 0 0 c 14 0 0 0 r
20 : r r r r r r r r 0 r r r 99 6d r r
30 : 0 r r r r r r r r r r r r r r r
40 : r r r r r r r r r r r r r r r r
50 : r r r r r r r r r r r r r r r r
60 : r r r r r r r r r r r r r r r r
70 : r r r r r r r r r r r r r r r r
80 : 51 50 4 0 2 d df 0 e 28 18 2 81 r r r
90 : 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
a0 : 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
b0 : 3a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
c0 : 80 0 4 r r r r r r r r r r r r r
d0 : r r r r r r r r r r r r r r r r
e0 : r r r r r r r r r r r r r r r r
f0 : r r r r r r r r r r r r r r r r
=======================================================================

Thank you,

Best regards,
Maxli

Hi Steve,

The same issue is in PAL / NTSC-J.
We also use the full black screen, the digital value is "11 80 10 80" whatever the pedestal register is 1 or 0 .
So, it seems that TVP detect the black level automatically without reference to the pedestal reigster setting.

Please help us to check the TVP registers in previous message.

Thank you,

Best regards,
Maxli

Hi Steve,

Do you have any update ?

Best regards,
Max

Dear Steve,

Thanks for your help.

Best regards,

Max

Hi Chris,

Thank you!

You are right! I made a big mistake..

The pedestal setting is bit 6 , it should be mask 0x40, not set 0x40.

We set register 07H is 0x20 to check the black level of the NTSC-M and it is workable.

Best regards,

Max

Good catch Chris. :-)

Sometimes the problems are not nearly as complicated as expected and solutions simple !!!

BR,
Steve

Dear Steve & Chris,

We sholud check the register settings again to find the obviously mistake.

Thanks for your useful support again!

The issue can be closed!

Best regards,

Max