Dear all,
This is Chris. Recently, my customer met some question on DS90UB948-Q1 and I hope you can give me some kindly help on it.
When PCLK is out of 48MHz, the DE signal of the screen will shake and the screen will shake, too.
But if we set PCLK<40MHz, the DE signal of the screen will not shake and the screen will not shake, too.
Below is some parameters of video timing:
|
SPEC |
customer's screen |
||
|
Typ |
Setting from UB941 |
Testing values |
|
|
DCLK |
48 |
47.98 |
49.5 |
|
HACT |
960 |
960 |
960 |
|
HBP |
16 |
32 |
31 |
|
HS |
16 |
32 |
15 |
|
HFP |
32 |
16 |
31 |
|
Htotal |
1024 |
1040 |
1037 |
|
Line Time(H) |
21.342 |
21.342 |
20.9 |
|
VACT |
720 |
720 |
720 |
|
VBP |
8 |
8 |
16 |
|
VS |
8 |
8 |
8 |
|
VFP |
45 |
45 |
46 |
|
Vtotal |
781 |
781 |
790 |
|
Frame ratio |
60.019 |
59.994 |
60.497 |
According to the datasheet of screen, it seems that once the width of DE signal reduces, one less line will be recognized inside the IC of the screen, which results that the blank interval is missing by 1H.
The display result is to shift up by one line as a whole.
Therefore, the DE signal plays a decisive role in the up and down jitter of the entire screen. But we cannot let PCLK >48MHz in this screen but in other screen, it seems OK.
Can you give me some suggestion on it?
Thanks and best regards!
Chris
