Part Number: DS90UB926Q-Q1
Tool/software:
Hi,
Please feedback the following questions.
Hi Kevin,
Is it unreasonable that how much time to produce how much CRC error count?
I don't fully understand your question? What is unreasonable?
How long is reset CRC error register 0x04 bit 5?
Register 0x4 on 926 is BCC timer
CRC error count 11000 per second, no flickering on the screen?
It's expected to see CRC errors typically at power up those are transient errors, you need to clear them after power up and monitor to see if you see any accumulation.
Regards,
Fadi A.
Hi William,
Question (3), it is not in power up stage , CRC error reach max around 6 seconds, Video looks stable (no flash), but , still see CRC error count to 11,000 even we rest CRC every second .
How are you clearing the CRC errors? How do you know it's not happening at power-up stage?
1. if we see stable Video, can we ignore the high CRC error count / which up to 11,000 per second ?
No, Common CRC error causes: Poor signal integrity, power supply glitch, startup errors. Back channel CRC errors indicate there is some sort of HW issue or schematic/layout issue, etc. This has nothing to do with video - Video signal is carried through the forward channel.
Could you monitor the CRC error count on the SER in registers 0x0A ,0x0B and 0x0C? Please clear initial errors by setting register 0x04[5] = 1, and then 0x04[5] = 0. After that, monitor registers 0x0A, 0x0B and 0x0C to see if there are any error accumulating.
If they are getting BC CRC errors then we need to figure out why by reviewing schematic, layout, cable type, cable length, connector, etc. One reason could be due to the cable insertion and return loss characteristics, particularly in the frequency range of the back channel communications. Usually we recommend high quality automotive cabling such as Dacar 535 to ensure the link can operate properly. Also, there could be an influence from the connector/layout as well.
Here is the SER registers that needs clearing and needs to be monitored
2. what maximum CRC error count can be accepted under what certain times ? ( error must under 100 or 1000 or what number per second or per ? seconds) for QC ( quality control) point of view ?
There is no max number, typically in our designs after you clear transient CRC errors you shouldn't see any accumulation. However, if you see one or 2 errors after hours of operation that might be ok as well but you shouldn't be seeing 1000s of errors accumulate after short period of time.
Regards,
Fadi A.
