DS90UB947-Q1: Why screen can not be recovered even short is over

Hello：

I set 947 register 0x64 to 0x05 when blank screen. But  the screen can not display Color bar. Then I set 948  register 0x64 to 0x05 using I2C command through FPD-Link. Screen can display color bar.(I use 947-948 paired in the project). So I think problem is happened on link 947 to 948. But I do not know why this will happen even I2C data can transmit correct from 947 to 948. Any suggestions ? Thanks

Hello,

What happens if you do a digital reset on the 947 after shorting the D2 lines?

Best Regards,
Casey 

The display is OK if I reset 947 PDB pin.  But screen can not be recovered if I only set register 0x01 to 0x01 or 0x02.

Hello,

You can use these steps to reset the OLDI interface clock including restarting the input PLL:

0x40 = 0x10

0x41 = 0x49

0x42 = 0x16

0x41 = 0x47

0x42 = 0x20

0x42 = 0xA0

0x42 = 0x20

0x42 = 0x00

0x41 = 0x49

0x42 = 0x00

Can you see if that also fixes the problem?

Best Regards,

Casey 

No. The screen blank after set these registers. 

Hello,

This is quite strange. What about resetting the 948 using register 0x01 instead of the 947?

Best Regards,

Casey 

The screen also blank using 948 register 0x01.

By the way. The 947 is set 24-bit Color Single Pixel Mapping mode.  The other project the 947 is set 24-bit Color Dual Pixel Mapping and the screen can recover when move tweezers. 

So there are some differences in these two modes?

Hello,

The main difference is that in dual pixel mode, both D2 and D6 carry sync information, so maybe shorting one or the other does not cause the display to blank permanently. In single pixel mode shorting D2 causes an interruption of all sync signals temporarily which may cause a bigger problem with your display. 

Is it possible to restart the OLDI source going to 947 after the tweezer test? What happens under that sequence? 

Best Regards,

Casey 

Hi Casey,

Double confirmed with customer, shorting d2+/- cause 948 enter AV mute mode, sending 0x555555 pattern could exit the black screen status. However, even we set 947 gate RGB (0x04 bit[4]) and 948 gate RGB (0x03 bit[1]), as well as fix the 948 AEQ status, it can't recover automatically after the short of D2 is removed.

Could you kindly explain why this happens and how to prevent 948 enter AV mute? Thanks.

Dongbao

Hello Dongbao,

I'm sorry but we do not have an explanation for this behavior. The device has not been tested for the condition of hard shorting one signal line during operation so unfortunately the behavior is unknown. 

Best Regards,

Casey