DS90UB947-Q1EVM: DS90UB947-Q1 + DS90UB940-Q1

Hi Team,

I really need your help.

Brs,

Bang

Hello Bang,

The pass on 940 just indicates no fault detected on input display timing. You may follow the following steps to evaluate the links:
1. Check the processor-947 link: you may read the Reg 0x5A[3,0] on 947 to make sure there's OLDI (LVDS) signal input and the frequency is stable. Then, you may get the OLDI frequency from the Reg 0x5F of 947 to make sure the frequency is what you expect.
2. Check the 947-940 link:
Firstly, check the lock and pass from the register on 940.
Secondly, do BIST to check the forward channel error and back channel error.

After checking Step1 and Step2, the output of 940 should be right. You can just read the CSI signal to make sure the whole link is all right.

Best regards,
Cera

Hello Cera,

Thank for your help. BIST you mean BISTEN or BISTC?. How to do BIST to check the forward chanel error and back chanel error as you said?. 

Which page in datasheet help to do this?

Best regards, 

Bang Duong

Hello Bang,

BIST means Built-In Self Test. When doing BIST, the serializer generates a pattern, and deserializer knows what the pattern should be, and they compare and list any differences as errors. BISTEN means BIST enable and BISTC means BIST clock select. You may refer to 8.3.13 section in 940 datasheet.

When doing BIST, you should set the register 0x24 on 940 to 0x01 (bist configure through register, use internal 50MHz clock for BIST, enable BIST). Do BIST as long as you want, and disable BIST by setting Reg 0x24 to 0x00. And check forward channel error by reading 0x25 on 940 and check back channel errors on 947.

Best regards,
Cera

Hello Cera,
I must use internal 50Mhz clock for BIST (BISTC) or which frequency i should use?. Pin fucntions said Bist Clock Select 0: PCLK; 1: 33Mhz.
After reading 0x25,I think Reg 0x25 only count error, right?.How to I know what error?. I do not understand how to check back chanel errors on 947. Can you give idea about it, pls?.
Finally, my email is bangdd@viettel.com.vn, can you give me your email so I can easily to request your help?.
Thank you so much,
Bang

Hello Cera,
I use FR4 trace connect DS90UB947 output to DS90UB940 on same PCB, so which mode I need config DS90UB947?. Set Cable Type FPD-Link III for twisted pair cabling or FPD-Link III for coaxial cabling? .
Thank you,
Bang

Hello Cera,
I need your help again.
I've followed your instruction and no error found ( Reg 940 0x25 = 0x00 ).
947 Reg 0x5A = 0xCD (11001101) ; 0x5F = 95 ( frequency is 148.5 Mhz like as I want)
940: BIST is enable, 0x25 = 0x00
Now I still cant read CSI-2 data from 940.
Have you written driver to read MIPI CSI-2 signal outputted from 940?. If not, can you support me write driver, please?.
Thank you so much,
Bang Duong

Hi Bang,

1. I must use internal 50Mhz clock for BIST (BISTC) or which frequency i should use?

    You may use either the internal clock or PCLK to do BIST. When using PCLK by selecting BISTC pin is set to 0, you can set the PCLK by Reg0x14 on 947.

2. After reading 0x25,I think Reg 0x25 only count error, right?.How to I know what error?

   Yes, it is the error count. When doing BIST, 947 compares the received data with the data 940 sent, and listed any difference as an error. So the error counter is the number of different bits. 

3. I do not understand how to check back chanel errors on 947. Can you give idea about it, pls?

    You can check 0x1B on 947 for back channel errors.

4. I use FR4 trace connect DS90UB947 output to DS90UB940 on same PCB, so which mode I need config DS90UB947?

   You mean you just use PCB connect 947 and 940? You use 947/940 pair just to convert LVDS to CSI? If so, did you configure the connection to single ended or pair? If single ended, please choose Coax Mode. If there's a cable between 947 and 940, the mode is determined by the type of the cable.

5. Now I still cant read CSI-2 data from 940.

   Did you check the errors after BIST? If you checked, and there's no errors. The fault may be from the processor or script.

Best regards,

Cera

Hi Bang,

If you want to verify the script for reading CSI, you may enable the pattern generator on 940 (disconnect 947) and read CSI data using processor.

Best regards,
Cera