ADV7610 - Dark horizontal lines

Hi,

 Below register configurations seems different from reference one. Please configure accordingly and let us know after that,

     // 0x98, 0x02, 0xF2 98 02 F5  Auto CSC, RGB out, Set op_656 bit

     // 0x98, 0x06, 0xA2 98 06 A6 ; Invert VS, HS pins

     // 0x44, 0xBA, 0x00 44 BA 01 ; Set HDMI FreeRun

 According to reference script 0x06 register is configured as A6 (i.e Positive polarity Hs/Vs/Field).But in your configuration it seems as negative polarity(98 06 A2).

 Please note that, by changing the polarity of the LLC clock output may be necessary in order to meet the setup and hold time expectations of the downstream devices processing the output data of the ADV7610. It is expected that these parameters must be matched regardless of the type of video data that is transmitted. Therefore, INV_LLC_POL is designed to be mode independent.

Thanks,

Poornima

Hi Poornima,

Thanks for your fast reply.

We modified register 0x02 of the IO map taking into consideration the reference value as below:

0x98, 0x02, 0xF7, // Auto CSC mode, no conversion, limited 16 to 235 output range, RGB color space output, data saturator disabled

We cannot set the register value exactly to 0xF5 because the downstream video pipeline does not operate in YPbPr color space but in RGB.

However, even after modifying the content of this register, the dark band issue was not solved.

Concerning the two other registers you pointed out, we did not modify them because of the following reasons:

• We use a negative polarity VSYNC to match with the downstream video pipeline (developed on FPGA). That is why we write 0xA2 instead of 0xA6 in register 0x06 of the IO map.
• We do not want the HDMI free run mode to be enabled as the input signal is properly controlled and we do not want a video stream to be injected when no data is at the input. 

Do you have any other idea on how to solve this dark horizontal line issue? I indeed believe it is something related to color, contrast, brightness...

Thanks,

Mattia

Hi,

Please crosscheck with your source whether RGB limited or Full range is coming from the source.

Register - 0x53(Readback of the HDMI input color space decoded from several fields in the AVI Info Frame) which is available to check whether RGB limited or full range coming from the source So accordingly set the input source to either RGB Limited Range or RGB Full Range input mode .

Full range sets the RGB levels (0-255): So set the input source to RGB full range and then the IO map 0x02, would be 0xF2.
Limited range sets the RGB levels (16-235): So set the input source to RGB limited range and IO map, 0x02 would be 0xF6.

Please note that,HDMI color space which is decoded from AVI Infoframe. The input range is set by control register INP_COLOR_SPACE and the read back register HDMI_COLORSPACE[3:0] ,The output color space is determined the control bit OP_656_RANGE.

Also by configuring the OP_656_RANGE between 0 & 1, We can increase or decrease the brightness.
For example: By setting "OP_656_RANGE to 0" and the display appears full brightness and to reduce the brightness, Set "OP_656_RANGE to 1".
Kindly note, If the HDMI receiver is configured for RGB output, Use CP_MODE_GAIN_ADJ to increase brightness (Affects all the three channels simultaneously)
If the HDMI receiver is configured for YCbCr output, BRIGHTNESS_CNTRL to increase brightness (affects only the luma channel).

Thanks,

Poornima

Hello,

we finally managed to solve this horizontal lines issue (for a reminder check the video in attachment).

The problem was caused by the digital fine clamp block present inside the CP. From page 103 of the Hardware User Guide (Rev.0) we understood that:

"The incoming video signal level is measured at the back porch. The level error, that is, clamp error, is compensated for by subtracting or adding a digital number."

This explains why what we saw on the video was looking like a filter applied to the whole line as soon as we had something touching/crossing the left edge of the frame (first pixel of each line).

To solve the issue we set to '1' the value of the CLMP_FREEZE field in register 0x6C[5] in the CP block (address 0x44). Observe that this register is not documented in the Software Manual (Rev.0). 

Kind regards,

Mattia

Hello,

we finally managed to solve this horizontal lines issue (for a reminder check the video in attachment).

The problem was caused by the digital fine clamp block present inside the CP. From page 103 of the Hardware User Guide (Rev.0) we understood that:

"The incoming video signal level is measured at the back porch. The level error, that is, clamp error, is compensated for by subtracting or adding a digital number."

This explains why what we saw on the video was looking like a filter applied to the whole line as soon as we had something touching/crossing the left edge of the frame (first pixel of each line).

To solve the issue we set to '1' the value of the CLMP_FREEZE field in register 0x6C[5] in the CP block (address 0x44). Observe that this register is not documented in the Software Manual (Rev.0). 

Kind regards,

Mattia