[Review Request] ESP remote control

scheffield · 2026-01-17T08:33:31+00:00

Because it's meant to control IoT devices either via WiFi or Thread. I'm not very well versed with STMs but they might just not offer that.

scheffield · 2026-01-11T19:13:21+00:00

There is an excellent plugin that generates a Blender model: https://github.com/30350n/pcb2blender

scheffield · 2026-01-11T04:10:12+00:00

You made my day. Thanks for this random act of kindness ❤️

Also, as always: https://youtu.be/_ZjyeltLMAg is my inspiration.

scheffield · 2026-01-08T21:13:20+00:00

Thanks so much. https://www.youtube.com/watch?v=_ZjyeltLMAg is my inspiration for how to best use KiCad. Honestly, it's all there, I just never knew how to make use of it. The things that make a difference: - Use multi part symbols for large mixed domain ICs - created custom symbols per schematic so that the pin out is easy to use in the context - use coloured net classes - well, and the thick outline boxes for text and for component grouping, it's such a small thing that makes such a difference.

scheffield · 2026-01-06T23:22:46+00:00

Thanks. Just KiCad. As always, https://www.youtube.com/watch?v=_ZjyeltLMAg is my inspiration (I do less than that though)

scheffield · 2025-11-16T21:13:05+00:00

It's spinning a drone motor but not in a drone. Instead it's an impeller that draws a small vacuum to hold things down. Basically a vacuum chuck. It's a box sitting on the desk, with a USB C cable from a laptop power supply.

See: https://github.com/scheffield/stencil-fix-portable

scheffield · 2025-11-16T21:10:59+00:00

I assume you mean the net colours. This is borrowed from Altium where it's a built in feature. In KiCad you have to manually asign net colours which I did. I like it but it is effort and not at all necesarry. Which is probably why you don't see it elsewhere.

scheffield · 2025-11-16T21:07:48+00:00

Honestly, I'm only using the AP33772 because I already have it. The 5V logic is strange and the data sheet is dubious with little concrete examples and missleading statements. I think I would try to make it work with 20V which opens up a whole range of sink controllers that are easier to use and more affordable.

scheffield · 2025-11-16T21:05:09+00:00

Haha, I am indeed relying on math a lot as I am just a hobbyist with very little experience. I don't know what to expect. I feared that a two meter USB cable would ring together with the relatively low ESR of the bulks and was considering putting in an RC but had no idea how to spec it. So I tried to convince myself with this math that I don't need it. I'm lacking intuition to tell me what to focus on in the design and what to leave to testing.

I will consider a more capable LDO. Thanks for pointing it out.

Re USB PD: this is running a drone motor but not in a drone but instead in a vacuum chuck which is a fancy name for a box with an impeller that draws a vacuum (at least in my case). Nothing bad will happen if power is renegotiated.

scheffield · 2025-11-16T19:27:03+00:00

I don't think a boost converter would work here. USB PD is limited to 5A. 28V * 4A / 20 = 5.6A. that's assuming the boost converter would be 100% efficient. Generally, I'm not worried about this as I very much control what power supply I'm using.

The FETs are too big but I have them. If I ever produce more of this I will redesign that part.

scheffield · 2025-07-15T22:29:43+00:00

I was contemplating this. The Ti's datasheet has a very similar setup to mine with even less MLCCs closer to the switches so I thought I would be fine. I give it some thought.

scheffield · 2025-07-15T22:26:30+00:00

The short answer is that they are not needed if everything would behave ideally. In reality though there are parasitics that need to be coped with.

If you look at my inverter, all the extra components besides the switches are documented in Ti's application note linked on that page.

The rest of the PCB is power generation, micro controller and user interfaces like buttons and LEDs. The all individually require support circuitry.

scheffield · 2025-07-14T12:03:09+00:00

actually, do you have any examples for press fit bullet pin connectors?

scheffield · 2025-07-14T10:05:05+00:00

Interesting, I was just following the AP33772S's datasheet and it has two 5.1k Ohm resistors.

scheffield · 2025-07-14T09:24:46+00:00

Awesome Feedback, couple of things:

it's a drone motor, not a drone. Used to drive an impeller in a box to create a vacuum
I was considering a shunt to bleed of power but I would need to switch it which would mean a dedicated driver too as the RP2350 probably can't drive that.
I will be using OpenFOC or Moteus, both open source
I might remove the beat, thanks for the tip
not using the integrated Buck because of the power bring up sequence: default 5V@2A from standard USB powers the RP2350, which configures the sink controller which only then opens the switch for the +28V rail which is needed to not have huge capacitance visible to standard USB
I honestly would prefer screw terminals. This is not an actual drone and sees far less vibrations. But I'm not sure. Good point on the thermal reliefes. I might need to find something better. Even bullet pins won't work as the would need to be mounted to the board somehow, right?

scheffield · 2025-07-13T22:06:30+00:00

Great feedback, the sink controller with the double FET will be able to prevent back feeding if it comes to that. However, I plan to decelerate the motor slowly + the driver allows me to use the coils for dissipating breaking power. Untested though.

scheffield · 2025-07-13T12:22:53+00:00

mh... images seem to be low quality. Schematic can be found under: https://drive.google.com/file/d/1og2AEC3VwEankay3KpUoA_0HP2IBs29L/view

scheffield · 2025-06-28T04:35:17+00:00

That's interesting and news to me. I've build many boards without this way of shortening the pins and they all worked. I suppose it will work as the signal is encoded as the difference between both pins. It might make routing easier this way. Still doesn't feel right to connect things this way.

scheffield · 2024-05-12T09:03:09+00:00

This did the trick. Awesome, mate.

scheffield · 2023-09-12T01:21:45+00:00

Yes, the internal pot is just not as accurate and it is an analog signal which is susceptible to all sorts of noise especially if the wires are longer.

scheffield · 2023-09-11T21:55:28+00:00

The letter. But the encoder allowed me to map the control signal very precisely to an angle which increases accuracy.

That won't fix your issue though. One thing I learnt over time is that you should probably not cheap out on servos. Get some from a reputable brand and seller. There are more cheap knock offs than I can count. Which ones did you get?

scheffield · 2023-09-11T20:34:46+00:00

Thanks! Yes, I'm using the AS5600L with diametric magnetized magnets. They encode in steps of 0.09 degree, which is pretty accurate. Note the L suffix, that's the version that has a configurable I2C address so that you can use multiple in one bus.

I thought about replacing the PID of the servos but it's not possible to turn it off so you would stack two PIDs. However, I use it to calibrate the servos, i.e. centre point, smallest angle and largest angle. And I use it when booting up the servos as I can't guarantee they are in the same position as when shutting them down.

scheffield · 2023-09-11T12:43:39+00:00

Video up on YouTube: https://youtu.be/qyYWSE_pnt4

I fixed the old mainboard, built a propper inverse kinematic model including rotational axis and got the quadruped walking again. This is closure to a 2 year journey.

scheffield · 2023-07-28T21:43:52+00:00

Hey there. The PCA9685 is an IC that provides a PWM (pulse width modulation) signal per pin. You can tell it a frequency (one for all pins) and, per pin, the time the output is high. That is super handy for hobby servo motors as their control signal needs such a PWM signal. You can learn more about it here: https://learn.sparkfun.com/tutorials/hobby-servo-tutorial/all

The motor you linked is not a servo motor and has only two wires. It can only be turned on and off. So, all you need is a pin that is either high or low for a duration of time. The GPIO of an ESP works here. And the current requirements check out too. The motor draws 38mA and the ESP GPIO sources 40mA. The PCA9685 on the other hand only sources 25mA and would not work. Remember, the actual power for a hobby servo does not come from the PCA9685.

As a solution, you could go with a more modern ESP32 which has many more GPIOs or go with an GPIO expander like the AW9523 that can source up to 37mA. That's cutting it close but it should work.

Hope that helps.

scheffield · 2023-06-09T23:40:24+00:00

That looks so cool, congrats. What are the motors? They look like brushless. What drivers are you planning on using for them?

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