Post Go back to editing

ADV7341 application problems 1

Adv7341 chip is used to output color stripe video. The oscilloscope collects and outputs waveforms where the positive level at the lowest point is not the negative level. According to the manual, the minimum level of waveform is -300mv. The lowest level of our output waveform is 0mV. How to adjust the lowest level of output waveform from 0mV to -300mv?

Parents
  • Hi,

      Could you please share your register configuration and we want to check your format & I2C related configuration ?

    Thanks,

    Poornima

  • SD
    CVBS
    I2C:
    ADDR1 = 8'h17,DATA1 = 8'h02,//reset
    ADDR2 = 8'h00,DATA2 = 8'hFC,
    ADDR3 = 8'h80,DATA3 = 8'h11,
    ADDR4 = 8'h82,DATA4 = 8'hCB,
    ADDR5 = 8'h84,DATA5 = 8'h40,
    ADDR6 = 8'h8C,DATA6 = 8'hCB,
    ADDR7 = 8'h8D,DATA7 = 8'h8A,
    ADDR8 = 8'h8E,DATA8 = 8'h09,
    ADDR9 = 8'h8F,DATA9 = 8'h2A;

  • Hi,

       If is an PAL test pattern, Please make sure with below register settings,

         0x17  - 0x02

        0x00 - 0xFC

        0x82 - 0xC9  // Your configuration is different

        0x84 - 0x40

        0x80 - 0x11

        0x8C - 0xCB

        0x8D - 0x8A

        0x8E - 0x09

        0x8F - 0x2A

    If it is an NTSC color test pattern, Please make sure with below register settings,

        0x17  - 0x02

        0x00 - 0xFC

        0x82 - 0xC9

    Please note as per specification for SD pattern(Page 82), CVBS output is available on DAC 4, S-Video (Y-C) output is on DAC 5 and DAC 6, and YPrPb output is on DAC 1 to DAC 3. So you should configure 0x82 register as 0xC9 but you have configured it as 0xCB. Please refer Table37 in ADV734x datasheet.

    Thanks,

    poornima.S

  • Configure and adjust the circuit according to the idea you provided, but the lowest level of the output waveform is still not reduced from 0mV to -300mv. Why?

Reply Children