This FAQ was generated from the following discussion: Black line on the Output from the ADV7282-M
I can't upload attachment to here, you can get attached file from the follwing link:
Hi Yuanyuan guo,
It looks like you are programming the ADV7282-M correctly.
One thing you state that with a PAL input, the output is 480 lines long. Is the output 480 lines long for NTSC inputs too?
The ADV7282-M outputs 487 lines of video in BT656-4 progressive NTSC mode. Could this be the cause of your issue?
Could you also try reading the registers 0x10 to 0x13 in the fail state.
Could you also try recreating the issue on an ADV7282-M evaluation board. If you do not have one you can contact your local Analog Device's sales office to have one shipped to you. I can forward you an email address if you do not have one.
thanks and regards,
[guoyuanyuan]: I can't confirm whether it is 480 lines long for NTSC inputs.
I used a PROMAX TV PATTERN GENERATOR GV-698+ as NTSC inputs.
The ADV7282-M outputs 487 lines of video in BT656-4 progressive NTSC mode. Could this be the cause of your issue?[guoyuanyuan]:I've always been confused. I must tell the receiver(backed device) the size of receiving data.
I set it to 1440x480,but in fact 1440x507 size of data is received.
[guoyuanyuan]:I used a NTSC-M inpus when issue occured.
Register 0x12---------0x10(sometimes it is 0x00 based on different pattern)
Register 0x13 ---------0x69
When I unplug the signal source,it automaticlly enters free-run mode(single blue color,and black line disappeared,receiving data is 474 lines) ,the register values is showed as follows:
Register 0x13 ---------0x78
[guoyuanyuan]:I have a ADV7282-M evaluation board in hand,and local Analog engineer Bob Gao have contacted me.
I think this may be parameters settings issue, I did a set of experiments as follows:
In order for the receiver to correctly receive video data, It is necessary to tell the szie of video data,also included video data + blanking data in platform side(receiver).
ADV7282-M output format video data video data + blanking data test results
BT656-4 1440x487 1728x525 Images is displayed correctly(no 10lines dark and a black line) ,but a error is receiver has received the 507 lines.
BT656-4 1440x507 1728x525 there is a black line at botton of image,no any software error
BT656-3 1440x487 1728x525 more than 10 dark lines at top of image,and a error is receiver has received the 507 lines
BT656-3 1440x507 1728x525 10 dark lines at botton of image,no any software error
Image is displayed correctly in the first set of experiments,and only has a software error.
The ADV7282-M outputs 487 lines of video in BT656-4 progressive NTSC mode,Why receiver does receive is 507 lines? I initialize ADV7282-M wiht parameters of "I2P AUTODETECT CVBS Single Ended In Ain 1, 480p/576p MIPI Out", Is it related to this settings?
Hello Yuanyuan Guo,
Thanks for reading those registers. Register 0x12 states that sometimes the ADV7282-M receives CVBS video of non-standard horizontal line length. This may be related to your issue.
You may be correct in this issue being due to a screen resolution issue. I will run some experiments in the lab to see if I can recreate your issue.
Note that when a CVBS source is disconnected from the ADV7282-M it will output a few frames of video of non-standard length (i.e. greater than 576 lines lines of video) until it enters free-run mode. These non-standard line lengths can sometimes cause input buffers on the MIPI receiving device to overflow.
I would advise implementing a line counter or similar control loop, to prevent issues in your back end processor.
Could you recreate this issue in the lab?
I think it is difficult to implement a detection mechanism in back end processor.
I'am checking it,thanks!