DS90UB948-Q1: DS90UB941AS-Q1+948 output lvds

Hello, 

Can you provide me with more information on the set up? Please share the operating mode of the 948 ie, dual lane/link input/output, PLCK rate, timing coming from the SoC, screen parameters etc... 

If possible can you share the specifications/datasheet of the display as well?

Best,

Shu

Thank you, below is my 941+948 configuration.

941:
WriteOfI2c_Byte(0x01,0x08); //Disable DSI
WriteOfI2c_Byte(0x1E,0x01); //Select FPD-Link III Port 0
WriteOfI2c_Byte(0x40,0x04);//DSI/D-PHY Port0 Digital Register
WriteOfI2c_Byte(0x4F,0x8C); //Set DSI_CONTINUOUS_CLOCK, 4 lanes, DSI Port 0
WriteOfI2c_Byte(,0x5B,0x01); //Force single FPD-Link III Transmitter mode
WriteOfI2c_Byte(0x0D,0x03); //GPIO0 Config
WriteOfI2c_Byte(0x0E,0x33); //GPIO1 GPIO2 Config
WriteOfI2c_Byte(0x17,0x9E);//i2c pass all
WriteOfI2c_Byte(0x07,0x58);
WriteOfI2c_Byte(,0x70,0x5A);

948:
WriteOfI2c_Byte(0x1D,0x05); //GPIO0 Config
WriteOfI2c_Byte(0x1E,0x55); //GPIO1 GPIO2 Config
WriteOfI2c_Byte(0x37,0xac); //MODE_SEL 20 Mbps
WriteOfI2c_Byte(0x49,0x80);//Dual FPD/OLDI output
WriteOfI2c_Byte(0x41,0x1f); //for esd

Then, is the configuration of my soc.

pclok 66.3MHZ 4Lane size：1920*480
hor total:570
hor.sync time :13
hor.back porch :14
hor.front porch :63

ver total:1938
ver.sync time :6
ver.back porch :6
ver.front porch :6

Display slowly goes from dark to light with dark spots  like:

948 video single output

lvds to mipi

screen parameters:

Hi, 

Thank you for providing this information, I will look into this and get back to you by the end of the week. 

Best,

Shu

Hi,

In DE only mode, I measured the lvds signal waveform output by the 948 as shown in the attachment, the amplitude does not seem to be very stable, does the 948 have the ability to enhance the lvds drive? If I want to turn into Sync Mode output, what do I need to do besides writing 0x80 to register 0x29?

Best,

Luuel
948_LVDS.rar

Hi,

Below is the circuit diagram of the 948 output

LVDS TO MIPI

I found that if I reset the lcd screen, the display briefly shows a 2 equal division soc output video, is this related to the problem I am experiencing now?

Hi，

I changed the 948 from De only Mode to Sync Mode Write948i2c (0x29, 0x80). If the 948 has been continuously powered off, the 948 will output the lvds signal, and the value of the read register 0x29 is 0x80, which is correct. If the 948 is powered on again, the 948 will not output the lvds signal. This can judge that the sync mode I set is abnormal, and how do I configure the 948 to output the Sync Mode?

Best,

luuel

Hi Luuel, 

You have the correct configuration for setting the 948 to Sync Mode. I recommend that you refer to the Application Note - DS90UB941AS-Q1 DSI Bringup Guide and trying section 3 the 941 Bring-up and debug flow to help isolate/eliminate the 941 from the system.  Then we can take a look at what is happening on the 948 side. 

Best,

Shu