DS90UB926 : I2C not responding when pattern generator used with internal clock.

Nicolas Pinault

Hi,

I use a DS90UB926 connected to a DS90UB925. My Host is connected to 925 through a I2C link. The video clock provided to 925 is 12.5MHz.. There are other I2C devices connected to 926. I can control them from host (through 925 and 926).

Everything is working fine.

Now, I would like to test the screen when there are no video clk and data provided to 925. For this, I setup 926 pattern generator. When I select internal divided clock (reg 0x65, bit 3 = 0), the pattern generator works as expected but I2C communications are broken till power cycle (or maybe reset but I can't control it from host).

Is there a way to keep I2C link working when pattern generator is running with internal divided clock ?

Regards,

Nicolas

over 9 years ago

0 Tamas Horvai over 8 years ago

Prodigy 30 points

Nicolas,

I am currently struggling with the same issue for DS90UB928. As soon as the pattern generator is enabled, I lose the link between the serializer and deserializer.

Did You manage to solve this?

Thanks,
Tamas

0 Nicolas Pinault over 8 years ago in reply to Tamas Horvai

Prodigy 130 points

Hi Tamas,

Unfortunately, I did'nt manage to solve this problem.

Nicolas

0 Nicolas Pinault over 8 years ago in reply to Tamas Horvai

Prodigy 130 points

However, if you fix this issue, I'll be interrested in the solution.

0 Jason Blackman over 8 years ago in reply to Nicolas Pinault

TI__Genius 14015 points

Hi Nicolas,

I suspect that it has to do with the combination of LF mode and the internal pattern generator. What clock divider are you using? This is set by indirect register 0x03 (accessed by 0x66 and 0x67). Here is an app note on the pattern generator that explains more: www.ti.com/.../snla132c.pdf

Thanks,
Jason

0 Tamas Horvai over 8 years ago in reply to Jason Blackman

Prodigy 30 points

Hello Jason,

I tried to follow Your suggestion from both sides. Setting the clock divider above and below the currently set value (8) has no effect, as soon as the pattern generator is enabled, the image is on the display, but all communication is lost.

I gave a try to overriding LF mode from the registers, with the same effect (except not even being able to enable the patgen after setting it).

Thanks,

Tamas

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DS90UB926 : I2C not responding when pattern generator used with internal clock.