DS90UB941AS-Q1: 941 communicate with 926/928/940

Amelie Zheng

Genius 10865 points

Part Number: DS90UB941AS-Q1

Hi Team,

My customer now meet a very strange question when using 941 and 926/928/940.

All of the following device 925/941/926/928/940 are the same and all are configured by hardware (resistances).

All of them, PCLK=66MHz/display are 1120*780/STP connect/Only use Lane0(Dout0 in941).

941*928, 925*926 and 925*928 are working normaly.

As for 941*926, the output of 926's RGB/lock/DE/PCLK are normal. But has no signal output in 926's HS/VS.

As for 941*928, the output of 928's CSI data and CSI clk are no signal at all.

When I talked with customer, they said 941/928 are the test board made by CAR OEM and my customers are responsible for the Display side(926/940).

They doubt whether because 941 has already assigned the specific ID, such as ID0. If 940/926 is ID1, they can't communicate with 941.

May I ask:

Whether the configuration are different when 941 connected with 928/926/940.
Why 926 only has no HS/VS output?
Is it possible that 941 has specific ID, such as ID1 so that it can't communicate with 926/940, which is,such as ID3?

Thanks!

over 5 years ago

0 Steven(Shenzhen) Shi over 5 years ago

TI__Mastermind 30515 points

please don't understand it from IDx number. in your case, only DE sync. is available and Hs/Vs is not active. this can work for panel so your 928 system can work. but 940 need hs/vs to recover.

pls dump the 941as register to us for analysis, it is better if you can tell us the 941as's reg. setting in your initialziation process.

regards,

Steven

0 user5977425 over 5 years ago in reply to Steven(Shenzhen) Shi

Prodigy 20 points

Hello!

Thank you for your suggestion. Now there is a problem. The video source uses ds90ub941. This video source is at the customer's place. We can't disassemble it or provide relevant startup information. The PCBA of the customer cooperates with this video source (using ds90ub941). Using ds90ub928 can drive the screen normally;

As described above, use the customer's video source (using ds90ub941):

1. Our PCBA can only output CLK, de and RGB data, not HS and vs when using ds90ub926;

2. Our company's PCBA uses ds90ub940, csi-2 has no output signal;

After returning to the company, we did the following verification:

1. We have made our own video source, using ds90ub925, cooperating with customer's PCBA (using ds90ub928), and our own PCBA of two schemes (ds90ub940, ds90ub926), which can work normally;

2. Our own video source (ds90ub925) removes HS and vs signals in hardware, and other signals remain normal. It is found that customer's PCBA (using ds90ub928) still works normally;

From the above description, we speculate that:

1. The video source used by the customer (ds90ub941) does not have HS or vs output after ds90ub926 decoding;

2. By modifying our own video source (ds90ub925), we can still drive customer's PCBA (ds90ub928) to light up the screen normally without inputting HS and vs in hardware;

In the end, our scenario is to use the customer's video source (ds90ub941) and our own PCBA (ds90ub940). In this case, how do we need to configure the ds90ub940?

0 Steven(Shenzhen) Shi over 5 years ago in reply to user5977425

TI__Mastermind 30515 points

i had replied to Ameilie for this same issue:

please don't understand it from IDx number. in your case, only DE sync. is available and Hs/Vs is not active. this can work for panel so your 928 system can work. but 940 need hs/vs to recover.

pls dump the 941as register to us for analysis, it is better if you can tell us the 941as's reg. setting in your initialziation process.

regards,

Steven

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DS90UB941AS-Q1: 941 communicate with 926/928/940