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I have designed a custom PCB with an ESP32 and an OV2640 camera module. The image contains some noise and I don´t understand where the noise is coming from.

enter image description here

My suggestion is that the data lines from the camera module to the ESP32 are too long (shortest 45 and longest 54 mm), but I´m not sure. And I´m unsure how I can solve this issue.

enter image description here enter image description here

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  • \$\begingroup\$ The camera interface here is parallel. So data lines should have the same length in order to make sure datas are reached at the same time. \$\endgroup\$
    – emre iris
    Apr 12, 2021 at 7:46

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If you think the problem is the traces length you might want to enlarge the clock period in order for the data edges to complete their transients.

Also, slow down the image capture.

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The problem is not noise on the data line.

The problem is noise on the AVCC line (the 2.8v power supply), caused by the high power draw when wifi packets are transmitted from the esp on the 3.3v data line, from which the 2.8v is derived.

To fix it, design your board to have a dedicated analog ground and power supply, with its own voltage regulator and decoupling cap. Consider a series resistor too (although unfortunately I can't tell you a suitable value for that, and nor can the datasheet - I'd start with 1 ohm and go up and down as needed)

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