ESP32s Wroom reliability

Projects General Guidance
1

Hello all

I have designed a breakout board for some ESP32s Wroom boards I have been using.

I have supplied the ESP with a decent quality Meanwell 3A PSU and added a further 100nf and 100uf cap after that supply close to the Vin pins of the ESP32.

I still however get fluctuations shown in the 5v power led I added on the board when you add a decent load that shares the ground connection.

For example, I have a second Meanwell PSU that feeds a couple of large D845WP servos.
They share a ground connection with my pcb and obviously the servo signal.
The servos moving will make the 5v PSU led that only feeds the ESP32s slightly flicker.

What else can I add to my PCB design that will help eliminate this ground interference?
I did think of a ferrite? Not sure how I implement that.

I may also move the commoned ground terminal nearer the Meanwell PSU. I am however surprised I get this issue.

My second question is ESP32 boot pins. I read in various places that people have issues with the ESP booting because EN isn't held to 0v (internal pulldown not cutting the mustard).

Also conflicting reports on whether GPI02 should be held high or low (again, issues with the quality of the onboard pullup/down resistor).

This list says different:
ESP32 Pinout Reference: Which GPIO pins should you use? | Random Nerd Tutorials

Any guidance? Thank you

2

I suspect it's a layout issue, poor routing of grounds and power, traces to thin, etc.

1 Like
3

Hmm. My ground is the whole bottom layer (pour). +5v is a 2mm track over about 70mm

4

For anyone here to do any debugging we would need to see your schematics and layout

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I will try and get that uploaded.
Just wondered what other smoothing options there were for the PSU

6

Usual rule of thumb for electrolytic smoothing capacitor is 1000uF per amp load.

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A ground plane is good but the ground currents will still take the path of least resistance. You may still have ground current problems depending on the layout.

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Post the data sheets for the PSUs you are using.
I'm sure you will have many suggestions

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未命名 -1 (rs-online.com)

10

Blimey. Never knew that? 1000uf per 1A?
I have always used the 100nf + 100uf combo no matter what the load.

The only times I have added a 1000uf is when my project has either a directly driven servo off the same supply (try to avoid that), or a HC-06 Bluetooth module (they are horribly noisy)

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That is for line (50-60 Hz) based supplies. For switchers the frequency is higher so lower value capacitors can be used.

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The usual approach is a "star" ground configuration, to avoid ground loops or voltage drops. Every major component is grounded separately to a single point, common to all.

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@anon64083092

The D845WP servos have a stall current of 10A and an idle current of 1.6A. The actual running current will be somewhere in between. You should have a supply that can provide at least 15A but your meanwell is only 3A. Running the servos would cause an overload and the PSU would go into hiccup mode. Depending on our layout, other circuits could be affected.

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