I am designing a VGA to HDMI board.for adapting 30 meters extension cable, firstly input VGA signals into video amplifier LMH6739 3 channels and 74LVC1G125DCKRE4, turn out to AD9984,then adv7513 HDMI transmitter, the current problem: 1.Is ADV7850 better？2. Can AD9984 or ADV7850 automatically adjust the vertical and the horizontal position ?3. I use MCU to measured and estimate the frequency of horizontal and vertical sync to know the input video resolution, is there any better method?
1.Is ADV7850 better？ AD9984 is only a display interface with 10-bit ADC whereas ADV7850 is a video and graphics digitizer and a 3D comb decoder.Generally,other solutions would require 2 chips to implement your requirement.But ADV7850 is capable of digitizing RGB graphics signals from VGA to UXGA rates into an HDMI output.2. Can AD9984 or ADV7850 automatically adjust the vertical and the horizontal position ? In AD9984,the logic sense of VSYNC and HSYNC pins can be automatically determined by the chip or manually controlled by Serial Register 0x12, Bits[5:4] and 0x14, Bits[5:4].3. I use MCU to measured and estimate the frequency of horizontal and vertical sync to know the input video resolution, is there any better method? In ADV7850,the register VID_STD[5:0] is used to indicate the input video standards.Further,the registers in CP map like CH1_BL (Address 0xB1,0xB2) ,CH1_LCVS ( Address 0xB3) and CH1_FCL (address 0xB8,0xB9) can also be used to read the status of the input syncs. In AD9984,the HSYNC count can be determined by using registers 0x26 and 0x27.
1.The company I'm working for isn't HDCP adopter,can we purchase ADV7850 and use it？
3.I think the sequence of configuration is to know the input format first,then configure AD9984 and ADC7513 according to the input format.Right?
I set AD9984 register 0x12 "0x18",0x14 "0x18",don‘t set register 0x01 and 0x02,the position is incorrect.
Please try to change the value of registers 0x12 and 0x14 as 0x00 and 0x04 as per reference script at 8372.AD9984AEvalBrdfiles.zip and check the sync position.
Note: The input polarity can be manually set only if the Bit-7 of both the registers is set to 1.
ADV7850 has HDCP keys which require you to be an HDCP adopter for purchase. Anyhow check with FAE/Sales team for ADV7850 non-keyed part availability.
And also please review our guidelines on HDCP enabled boards and devicesRestrictions Relating to the Distribution of HDCP-Enabled Parts
But If you are not an HDCP adopter you might consider an ADV7842 which has the basic same features as the ADV7850 but comes and a non-HDCP adopter
AD9984 registers 0x01,0x02,and 0x03 register value is derived from the video timing.Please refer table 10 for the Pll divider,VCO range and charge pump current register configuration for corresponding video format.
Note that increasing the gain setting results in an image with less contrast.And also offset control shifts the analog input, resulting in a change in brightness. For more details refer section -GAIN AND OFFSET CONTROL.
ADV7842: HDMI receiver Support, Four 170 MHz 12-bit ADCs,3D ,External SDRAM Support and also other features has described in datasheet.