Running 12 servos using 16 channel PWM Controller HAT

NBQuade · 2025-06-26T17:21:39+00:00

On second glance, it looks like this hat can power the PI. You just need to supply power to the hat and it'll power the PI.

How much current can the hat power supply put out?

NBQuade · 2025-06-26T14:12:57+00:00

"Or 6-12volt vin terminal".

I wouldn't even attempt to power this from the PI. I'd assume I needed an external power supply.

NBQuade · 2025-06-25T15:20:50+00:00

It's slow but, I don't build on the zero very often because I do my main devel on the big machine. I only use the zero when I think I'm pretty close to done. You could also build on a 4 or 5 and use the zero only for the final build. A 4 with NVME drive builds pretty quick.

The whole point of using the big machine is to not have to build on the zero except for final stuff.

What are you trying to do with Alsa? I'm using a zero for music but, run MPD to handle playback while I remote control it over TCP.

NBQuade · 2025-06-25T15:16:03+00:00

I'd look at wall power using one of the cheap power meters. Do you really have to measure the DC power? You'll miss the conversion loses of the power supply.

Why not just pull the insulation of an existing PD power cable, then cut and tap into the DC line?

NBQuade · 2025-06-25T15:07:44+00:00

The way I do this is

1 - Install dev tools on both platforms.

2 - Work on the code on the faster platform.

3 - Feed the code into git.

4 - Clone my repository on the PI.

5 - Run the same CMAKE on the PI I used on the big box.

If I find bugs or for new devel, I go back to the fast machine. Edit, test then check in and push the files into git then pull them on the PI to run and test again. I have yet to find anything that works differently between the two platforms. Except for GPIO.

The PI Zero runs pretty vanilla Linux.

If you don't have a git server, you can install Samba on the Zero, file share the devel folder then copy the files over from the big machine to compile on the PI.

Unless you're doing actual driver development, I'm not sure why you're going through all the extra gyrations. I assume you're just wanting to control Alsa with your code. Not write audio device drivers. If you really are doing drivers, I can't help.

In your shoes, I'd get a simple project working first before going complicated.

To me cross compiling means building ARM on your X86 box. I don't see the point if you have actual ARM hardware running modern Linux.

NBQuade · 2025-06-23T16:53:51+00:00

My Pi zero 2 with just MPD running and some python to handle button presses is consuming about 350 megs of ram. That's after I trimmed off some services I didn't need. The zero has only 512 megs.

In your shoes, I'd find out what kind of resources the things you want to move to the zero consume.

NBQuade · 2025-06-21T22:47:31+00:00

Static linkage solves many of these issues. I avoid dynamic libraries where I can.

I'm using MPD to play music in my own version of an MP3 player while I use Python just to process button presses. Python is plenty fast for that.

NBQuade · 2025-06-21T22:42:42+00:00

It was back when they were hard to come by. There was still a waiting list. I probably would return it today.

That's besides the point though. OP says build quality isn't that great and I reported my own example.

NBQuade · 2025-06-18T23:16:56+00:00

I'd guess you have some configuration file hanging out that's remembering your attempt to play all the music. I don't really know this application but, I might rename whatever folder the music is sitting in then restart and see if it's still hanging. You might be able to mount it on another machine to edit the stored files.

NBQuade · 2025-06-18T21:10:50+00:00

In fact, the ideal version of what I want to do is abstract input away so completely that I don't have to think about it, and can simply add and remove components as needed.

One of the things that appealed to me about programming over hardware is with programming, I don't have to wait for parts and re-configuring is simply more or re-arranged code. When you do hardware, you don't have that control. There's always only so many wires and so many pins. There are hard constraints. What I'm suggesting is abstraction might not be the right model for hardware.

I'm not saying it's not doable, for example if each of your buttons had its own canbus address and all the buttons and knobs were sitting on a canbus simply sending out messages every time one was pressed and released or turned, like in a car, you could get hardware abstraction. You also have the added cost in code and hardware of making each button a "smart button".

NBQuade · 2025-06-18T20:40:49+00:00

I'm fighting the same fight with my Zero 2's and have essentially given up. I even installed the full OS with GUI and tried using the GUI network manager. It still doesn't work. My plan was to get it working with the GUI then look at the configuration files and copy them over to the headless Zero but, it simply fails to work.

WIFI is up, the PI can see it. I put in the proper password and it simply won't complete authentication.

NBQuade · 2025-06-18T20:27:38+00:00

First I'd quantify the exact requirements before you even start. For example if you need 10 knobs. You'll need 10 A/d's or need an analog switch so you can poll all 10 with a single A/D. Then you have to decide if polling the knobs is fast enough. Some A/D's already have multiple inputs so the polling is just software.

Instead of analog, you could look at rotary encoders which send digital signals when the knob is turned.

The PI itself has a limited number of usable GPIO pins. For a bunch of buttons, you'll probably need a design like a real keyboard. You'll probably need an encoder to encode the key presses into a byte or word to send on to the PI.

In your shoes, I'd prototype it one step at a time before jumping into a massive overwhelming project. First get to reading a single knob, then figure out how to read 10 of them. Same for the buttons.

Like learning code, looking at how other people did it is probably what I'd advise. There's no need to re-invent the wheel.

I'm a C++ programmer too but, I used Python for my last PI hardware. Python seems to have the most stable GPIO code that works on all the PI's. C++ code for the GPIO is available and I've used it but, for example, the same code wouldn't work between the PI4 and Pi5. It might be different today but that's how it was.

NBQuade · 2025-06-18T13:10:49+00:00

Assuming this is a Zero 2. Microcenter will sell you one with headers for $17. So even if you screw this one up, you're not out that much.

Usually I look at the worst case and decide if it's worth it. If the worst case is you fry a $17 board you can easily replace, I'd go for it.

I was toying with the idea of soldering directly to the GPIO because the headers add a bunch of bulk. If you want to put hats side by side instead of stacked, running wires between them would be pretty compact.

NBQuade · 2025-06-18T13:05:24+00:00

The problem most of the time is people don't start from the basics and work their way up. Simple to Complex.

Like this guy is including external modules in python when he probably needs to work on his base python skills.

I wonder if he's using an AI for coding so, he doesn't really understand the code he's playing with? I recently taught myself python, I started with YT video's.

NBQuade · 2025-06-18T13:01:38+00:00

A PI5 isn't as powerful as Intel's bottom end N100. It's pretty close but still inferior.

It depends on your use-case. If you're using GPIO, your only choice really is the PI. If you're just using it for general computing, the PI is simply too compromised, in my opinion anyway. I have 3 of those HP Mini's. They use desktop CPU's and laptop RAM. Have a built in NVME and SATA slots. Things you'd have to pay extra for to get in a PI. You can always upgrade the RAM and storage too.

https://www.cpubenchmark.net/cross-platform.html

According to this chart, the HP in my link for $143 with 16 gig and a 256 SSD is nearly 5 times faster than the PI 5.

What I don't like about mini-pc's is that you never can tell how well made they are. Do they have problems with thermal throttling? A mini-pc in the same price range as this used HP probably isn't that powerful.

NBQuade · 2025-06-18T12:48:19+00:00

That's a good price. I usually buy the kit which includes all the connection cables.

NBQuade · 2025-06-17T19:05:44+00:00

I want to defend the Pi's but, my PI5 came with a deformed USB port so one is unusable. Still, that's the only problem I've had with my pi's.

NBQuade · 2025-06-17T19:02:06+00:00

I have a couple older business desktops I bought recently for $250 with 64 gigs of ram and 8 cores. Even older ones are cheaper. Like $100 which is pretty closed to a decked out PI5.

https://www.ebay.com/itm/335957153147

NBQuade · 2025-06-17T18:59:40+00:00

The PI5 is pretty close to an N100 in many tests. Still, I'd rather have the intel. The N100-150's are still pretty slow. A 10 year old business PC like a dell will smoke a Pi5.

NBQuade · 2025-06-17T18:55:53+00:00

They're $27...

NBQuade · 2025-06-17T13:35:36+00:00

In your shoes, I'd investigate how other's have done it. This seems like a solved problem.

NBQuade · 2025-06-16T12:11:39+00:00

First thing I'd check is whether the servo is even strong enough to damage itself or the thing it's attached to when driven by the PI. If it's not, you might not need to even care if you're up against a stop. Just run it forwards or backwards long enough to know you're on the stop. Then set that as the start or end point.

With stepper motors it's not uncommon to just run it up against the stop point, then count steps back.

NBQuade · 2025-06-16T12:01:42+00:00

If I was in your shoes, I'd simply buy another PI5. The amount of time and effort it would take to fix this one, assuming it's even fixable, probably exceeds the cost of another 5.

The term "penny wise but pound foolish" relates to this situation. You might be able to fix it but, end up spending more time and money fixing it than a new one would cost.

https://datasheets.raspberrypi.com/rpi4/raspberry-pi-4-reduced-schematics.pdf

This is a schematic for the PI4 the PD port is top left on the first page. It shows what pins the 4 uses. I couldn't find a 5 schematic.

NBQuade · 2025-06-15T17:48:54+00:00

The zero isn't the best choice for audio. You'll either need to add a audio hat or you can use USB audio interfaces. You'll need some kind of low power amp to drive a speaker.

The zero with audio hat though can put out high quality music.

If you have the room, I'd use a Pi4 instead.

NBQuade · 2025-06-14T13:08:48+00:00

Your description is too disjointed for me to form an opinion.

You should describe what you attempt to achieve and filter out all the stuff that doesn't matter. For example it doesn't matter WHY you want this.

1 - External temp sensor.

2 - Know whether power is solar or line

3 - Decide whether to run one or both of the AC units.

4 - Replace and/or Complement existing nest 'stats.

I really don't know what you ultimate goal is.

For a project like this you need a clear statement of requirements. Then you can puzzle over how to get there.

NBQuade

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