Studying ESP-EYE V2.1 ref design. A few questions...

[zliudr]

So I'm trying to make my own board with a camera. I am using ESP-EYE reference design:
https://www.espressif.com/en/support/d ... s?keys=EYE

In the design, if you go to the camera section, you see lots of 0 ohm shunts.

Ref design

Screenshot 2021-08-28 181536.jpg (54.34 KiB) Viewed 4206 times

Here is a photo of the board.

Dev board

MFG_ESP-EYE_Bottom.jpg (81.68 KiB) Viewed 4206 times

If you look above the ESP32 module, there is a row of 12 shunts in a long and narrow white rectangle. So why do they want those shunts everywhere? It's not just on these pins. It's also on the power supplies etc. if you download and open the schematics .pdf file.

I originally thought they wanted different net names across the resistors which might not be resistors at all but the photo shows the resistors are indeed there.
More on power and ground:

More shunts for agnd-gnd and power supplies

Screenshot 2021-08-28 182554.jpg (48.97 KiB) Viewed 4204 times

[username]

This is typically done on new designs. In many of those 0 Ohm locations adding say a 200 ohm resistor on a data line will help reduce EMI. On power supply lines adding a valued resistor in those 0 Ohm places will act like a filter circuit to make the supply rail
more clean from noise / spikes. SOoooo. you start off with 0 Ohm, and if later you find out you need to use these options by adding a valued resistor, you can without making a board redesign.

[zliudr]

Thanks @username!

I'll read more on this especially on the EMI reduction. So as a designer you can have test engineers test and vary the resistance until they achieve best results?

[username]

So as a designer you can have test engineers test and vary the resistance until they achieve best results?

Yup.

[ESP_Sprite]

Also, given that these are devboards, they provide for an easy way to modify the board without having to resort to cutting traces. Want to measure a power rail? Just desolder the 0 ohm resistor and replace it with a low-value shunt, then measure the voltage drop to get the current. Want to disconnect a part because you need to use the GPIO for something else? Simply knock off the 0-ohm resistor. Need to probe a signal? Solder a wire to one side of the 0 ohm resistor. Etc.

[username]

Good point ESP_Sprite

[zliudr]

Great! Thanks @ESP_Sprit! I guess I can skip a few of them since I could do a solder jumper if I need to maintain separate net names across connections and still have the option to more easily cut the trace or solder it back. For anyone not comfortable with that, a 0 ohm resister is easier.

[zliudr]

Good point ESP_Sprite

You can learn something everyday!