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ADV7179 COLOR ISSUE

HI All,

    

I was facing issue with ADV7179 encoder(Some colors are missing,when we enable bar pattern.)

Input clock frequency to ADV7179 - 27MHz from FPGA.

Voltage levels are proper,Ref voltage to ADV7179 - 1.22V.

I am getting all the I2C read ack when i was writing into registers.

Below are the registers we are configuring.

#define I2C_MODE_0_VAL      0x45
#define I2C_MODE_1_VAL      0xB8
#define I2C_MODE_2_VAL      0x00
#define I2C_MODE_3_VAL      0x80
#define I2C_MODE_4_VAL      0x08
#define I2C_TIME_0_VAL        0x05
#define I2C_TIME_1_VAL        0x02

#define I2C_TIMERESET_VAL    0x89
#define I2C_SUB_FREQ_0_VAL    0xCB
#define I2C_SUB_FREQ_1_VAL    0x8A


/* Clear test pattern */
#define I2C_SUB_FREQ_2_VAL    0x09
/* Exit Power-down mode */
#define I2C_SUB_FREQ_3_VAL    0x2A
#define I2C_SUB_PHASE_VAL   0x00
/* Monitor polarity is handled via DVI Sync Polarity Register */
#define I2C_DVI_SYNC_POLARITY_VAL        0x00

Note: I tried configuring registers with different combinations but the above config is the best one.

What i want was PAL resolution internal color bar composite on channel A.

Output of DAC A connected to TV.

The same reference design provided in ADV7179 datasheet, i was using.

when i play the actual video on DAC A instead of Color bar.Only proper color i can see in the screen was from 70% to 100%. Remaining 0 to 70% is fixed color was light blue/green always fixed in that area.Attached images and video for reference.

The same problem with internal color bar pattern also.

Please help me out.

Parents
  • My first comment would be that FPGA clock outputs are not very stable or accurate.  This can cause color distortion.  This is why you will see all our reference designs using crystals or oscillators for the 27MHz source. 

    If the color burst is not exactly 3.579545MHz then the sink will have issue with the stream.

    If the 27MHz is PLL generated in the FPGA then it will not be accurate.

Reply
  • My first comment would be that FPGA clock outputs are not very stable or accurate.  This can cause color distortion.  This is why you will see all our reference designs using crystals or oscillators for the 27MHz source. 

    If the color burst is not exactly 3.579545MHz then the sink will have issue with the stream.

    If the 27MHz is PLL generated in the FPGA then it will not be accurate.

Children