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Original question:

SN65DSI83: SN65DSI83 TEST

SN65DSI83: Only test patterns can be displayed, and MIPI images cannot be displayed

hailei yang
Prodigy 20 points
Part Number: SN65DSI83


We upgade our PCB board, and the new version using 25M ref clk, the old using 32M ref clk.
I set i2c register as old one, see nothing.The screen is just completely black. Limited by the CPU's clock source, I am unable to provide an accurate 32M clock source, but the 25M clock source is accurate.

1. Will the same I2C sequence cause the screen to fail to light up when the clock source is different?

Under the 25M clock condition, I tried to make SN65DSI83 send out a test pattern, and it could display normally. This proves that the LVDS side circuit is normal.
In a 25M environment, I regenerated the I2C initialization sequence using the software, but the screen still showed no change.
We also measured the signals on the MIPI side, and the two pairs of differential lines, DO and D1, always have data.

2. I have attached the new 25M initialization sequence. Is there an obvious problem with this?lvds-time-porch.JPEGlvds-time.JPEGmipi.JPEGlvds.JPEG
  • 0
    TI__Mastermind 26320 points

    Hi Hailei,

    Using the 25 MHz clock source with a multi0plier of 2 outputs 50 MHz LVDS clock. Could you check what value is set on the 0xA register?

    After programming these values, please enable test pattern to verify that these timings are valid and output to the display. If this is confirmed, then the next step would be to use the DSI input as video source instead of generating test pattern.

    After programming these values, is there an output on the LVDS output? Please check the waveform on the LVDS clock output using a logic analyzer or oscilloscope, to verify activity and frequency on the output.

    Best regards,
    Ikram