Help needed: Custom PCB - Connecting OV5640 to ESP32-S3-WROOM-1U

[MPsaradellis]

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Issue or Suggestion Description

Hi everyone,
I am currently working on a robotics project and designing my a custom PCB. I don't have a lot of experience with custom board design yet, so I want to make sure I get the schematics right before ordering. I’m trying to make the design as robust as possible and include hardware fallbacks in case I make mistakes.
My Setup:
Power: LiPo Battery (4.2V max) -> LDO to 3.3V for the ESP32.
MCU: ESP32-S3-WROOM-1U-N16R8.
Camera: OV5640 module (connecting only via FPC cable).
Camera Power: 3 adjustable LDOs to ensure the voltages are strictly within the datasheet ranges.
Here are the links to my current schematics (ESP, FPC connector, Power supply) and the OV5640 FPC (NOT PCB BOARD ) datasheet (it's a datasheet from China):

(Note: I have already read through this thread about the OV2640, but my application is specifically for the OV5640, which has may different requirements and a different datasheet......if you consider that it is the same please tell me)
I have a few specific questions regarding the schematic and would really appreciate your guidance:

1. Camera Power Supplies (3 LDOs vs 2 LDOs) According to the OV5640 datasheet, the camera requires 3 specific voltage supplies with certain ranges. I added 3 separate adjustable LDOs set to 3.0V (AVDD), 2.75V (DOVDD), and 1.5V (DVDD) to be absolutely sure I am within the limits. Is this the right approach, or is it overkill? Should I just use 2 supplies (e.g., 2.8V and 1.5V) like I see many others doing in their designs?
2. 0-Ohm Series Resistors on Camera Pins Looking at the official ESP32-S3-EYE schematic, I noticed they placed 0-ohm resistors on all the camera pins (D0-D7, PCLK, VSYNC, etc.). Is it necessary or highly recommended for me to do this as well for debugging/testing? Should I put them on all pins, or maybe just on the I2C lines for example (in case the traces get long) just to be safe?
3. External Oscillator for XCLK I came across this issue on GitHub (#706) regarding the XCLK, and it got me really worried. Is there a chance I will need an external hardware oscillator for the camera's XCLK instead of relying on the ESP32's internal clock? I was thinking of adding a footprint for an external oscillator as a bypass circuit, using 0-ohm resistors to select between the ESP's clock and the external one. This way, I can test both on the actual PCB if something goes wrong. Is this a good/standard idea?
   Thank you so much for your time and help! I really want to build something reliable and anticipate any potential errors.

[WangYuxin-esp]

@MPsaradellis
1）Each of the three power supplies needs to provide a stable LDO.

2）These resistors are only for reserving test points. VSYNC and PCLK can be reserved, but the others are not necessary.
3）You can use the SOC (configure XCLK) or an external crystal oscillator to provide the clock (configure xclk_pin = -1).

[MPsaradellis]

@WangYuxin-esp Thank you for the clear and helpful response!

Based on your feedback, I will keep the three separate LDOs to ensure maximum stability. Just to be completely sure, is it best to target the exact "typical" values from the datasheet table you provided (e.g., 2.8V for VDD-A and 1.5V for VDD-D)? I will also remove the 0-ohm resistors from the D0-D7 lines to simplify the board, keeping them only on VSYNC, PCLK, and the I2C lines for debugging purposes.

Finally, I will implement the hardware fallback for the XCLK using 0-ohm resistors to easily switch between the ESP32's SOC clock and an external crystal oscillator. Regarding the external oscillator, would you recommend tying its EN (Enable) pin permanently HIGH, or is it better to connect it to a spare ESP32 GPIO so I can control ?

Thanks again for your time and excellent support!

[WangYuxin-esp]

If there are any unused pins, it is recommended to use GPIO to provide the XCLK clock to the sensor.