ante posted:

You'll want to switch the negatives though, not the positives. It won't work properly, otherwise

babyeatingpsychopath posted:

The diagram is getting a bit strained, but it's basically the same concept. Each of those boards is a replacement for a relay. However, instead of a relay having a normally open and normally closed contact, this one only has a normally open contact that can ONLY switch + to LOAD.

So your pin names have changed slightly. There's no more "COM" because COMmon is now directly connected to DC+. DC- is now "-". "GND" is the reference to the microcontroller. If you're powering the micro with USB, do not connect "DC+" to "BAT", but do connect "GND" on the FET board to "GND" on the micro. "IN" is now called "PWM". That's it.

cruft posted:

Whoa, hey, can this person's microcontroller take 12V?

That relay board they're using has a neat feature where it provides an on-board buck converter with 5V out. They may be powering their microcontroller from that, it's not clear from the video they posted. But it looks like a microcontroller that will let the blue smoke out if you give it 12V.

ante posted:

They're N-FETs, which can't do high side switching.

Given that the gate needs to be at the source voltage+10v (for example) to be on. When the transistor is on, and the drain is connected directly to the power source, then the source will be at, say, VCC-0.1V. So unless you have a special power supply for the gate that is above your battery voltage, you'll never get a proper turn on.

babyeatingpsychopath posted:

Yes, I selected that specific board because it's got a 5V regulator good up to 16V input.

cruft posted:

babyeatingpsychopath posted:

Yes, I selected that specific board because it's got a 5V regulator good up to 16V input.

How can we, as casual hobbyists, determine whether those are high-side or low-side switches? For something like this the topology is already figured out, right?

Foxfire_ posted:

Mohamed Atalla can have an alliterative superhero name for making all of modern electronics possible.

Foxfire_ posted:

Mohamed Atalla can have an alliterative superhero name for making all of modern electronics possible.

For those, there is no real way to know definitively since there's basically no documentation. Basically just guess because n-channel are more common. A less sketch/more expensive part would be telling you the chip on it, and the datasheet will say what kind it is (+lots of other things like max temp, transfer functions, switching speed, ...)

power crystals posted:

Is there a recommended board/micro for something that can do USB host, including enumerating devices through hubs (which it seems like basically everything has a disclaimer including lack of support for)? Ideally something cheaper than a full on Teensy 4 or similar. The RP2040 claims to have host support, but the only things I can see describing it is adafruit managing to fake it by bitbanging its IO pins (which would work, I guess, but I'm hoping there's something more native) which seems to contradict the statement that it has host support native. This would just be for HID or other very slow devices so USB 1.1 max speed is fine. A single USB controller that does both/OTG is also fine, I don't need it to be a client. 5V native IO preferred for the rest of the circuit but I can use shifters if that makes the USB side easier.

Not specifically looking for an arudino-compatible though that'd probably be the easiest option, but this is the closest thread to "general embedded development" I know of so forgive me if I picked the wrong one.

babyeatingpsychopath posted:

Is there a BOM available?

If you make the thing, is there a way to point it at some other double-secret server?

PDP-1 posted:

Are analog RC filters on the switches an option?

cruft posted:

On the one hand, I'm really proud of myself for squeezing enough performance out of an 8MHz CPU to get software-debounced drum pad hits that apparently only close the momentary switch for under 20ms.

On the other hand, I'm appalled that this chip is running at almost twice the clock speed of my first desktop computer, and all I'm doing with it is asking over and over if 14 buttons have been pressed.

cruft posted:

On the one hand, I'm really proud of myself for squeezing enough performance out of an 8MHz CPU to get software-debounced drum pad hits that apparently only close the momentary switch for under 20ms.

On the other hand, I'm appalled that this chip is running at almost twice the clock speed of my first desktop computer, and all I'm doing with it is asking over and over if 14 buttons have been pressed.

cruft posted:

Is it possible for a USB device to know what host it's talking to?

I'm working on this toy drum controller for Wii Rock Band, and it's just beyond me how to get it working right in this PC game called Clone Hero. The interface is this bonkers combination of 12 gamepad buttons for 9 switches, and I've got it working on the Wii, but I'd like to have it go "oh, you're a PC, you get one button per input switch". Without requiring the user to do anything.

Is that even possible?

Hadlock posted:

Yeah there's almost some sort of host client negotiation going on. The controller is almost certainly sending a digital signal not raw analog values. The last fully analog controller was possibly the Atari 2600 joystick

shame on an IGA posted:

even just on/off digital buttons have been fully serialized since at least the NES, probably earlier

babyeatingpsychopath posted:

I think you could have a device with two Endpoints; one for the Wii which is standard and one for the PC. After the PC gets all the data, then it requests endpoint 1 and your code does the "1 button=1switch" mode. If the host never requests endpoint 1, you default to endpoint 0 and assume that's the Wii.

Cojawfee posted:

Is this a custom thing you're making? Is it possible to just put in a switch that goes between PC and Wii mode? Seems like that's what a lot of devices do these days. There's either a switch or a button combo you do to switch between host modes.

Deadite posted:

That's interesting, I don't know much about lighting controls and thought this whole thing would be much simpler than it is turning out to be. Do the DMX LED controls come in smaller versions?

I make neon-style LED signs and I'm trying to animate my first sign, but if this works it opens up a whole new area for me.

For this first one I just need the three sections to blink in sequence to look like the teeth of a chainsaw are moving:

Sagebrush posted:

Game Port joysticks, which were still available until the early 2000s, have dedicated pins for each button, and connect directly to the axis potentiometers and do the ADC on the computer. No logic on the stick itself at all.

Deadite posted:

That's interesting, I don't know much about lighting controls and thought this whole thing would be much simpler than it is turning out to be. Do the DMX LED controls come in smaller versions?

I make neon-style LED signs and I'm trying to animate my first sign, but if this works it opens up a whole new area for me.

For this first one I just need the three sections to blink in sequence to look like the teeth of a chainsaw are moving:

wolrah posted:

I know this is way late for your target of Halloween on this particular project, but if you are interested in building these sorts of things in general and want to animate them I strongly recommend that you get to know addressable LEDs. WLED firmware on an ESP32 takes literally minutes to set up from unboxing the hardware to animating LEDs and gives you a nice web interface that's even mobile friendly to control it from (as well as support for basically every network automation protocol you might want).

Addressable LEDs are not always the right answer but they're cheap and easy enough these days that they can be used to brute force a solution for less mental effort than doing it what might be the absolute most cost or power efficient way.