I just can’t come up with any compelling use for a raspberry pi.
And things like the ESP-32 have reduced the Pi's practicality on the other end where you just need something powerful enough to read and transmit data from a sensor.
Especially with ESPHome making it so easy to integrate with common sensors without writing code.
That said, the Pi Zero W is pretty cheap and small (similar in size to many ESP32 development boards) so it provides a nice upgrade path if you want to do more processing on device, exceed a few megabytes of ram, etc
This has just been one of my largest pet peeves with the entire Pi lineup. The Pi 5 is the worst offender that idles at like 3 watts doing jack shit. That's an entire 3000mAh battery gone in under four hours that would've easily lasted several days on an average smartphone SOC with twice the memory and speed.
My first reaction was "Well, the OS is open -- isn't it? Just set up good power management yourself and publish it for all to use, and it'll probably get accepted upstream eventually."
But then I remembered: The OS is open, but the hardware is not (because -- in one word -- Broadcom).
But maybe with an IPO, they can generate enough cash to get their own CPU started up. Maybe something based around [checks flip-chart] RISC-V or something, with enough documentation to allow people to fix the [checks excuse card] power management problem.
They've certainly shown some willingness to work in that direction with the RP2040.
Perhaps that will change: After all, how many engineers do you know who feel motivated to hold down regular mid-tier jobs at two publicly-traded companies?
If all a person needs or wants is a fairly tiny computer and it doesn't need to be new/shiny, then there's off-lease corpo boxes that are faster/better/cheaper.
If all a person needs or wants is some GPIO to hack on hardware with, and doesn't want a real OS on the back end of things, then maybe an Arduino or ESP32 or RP2040 or something might be better and cheaper.
But if a person needs or wants all of that in one box, then: A Raspberry Pi may well be the right approach. (Some folks like hacking with a real OS; this is fine. We used to use things like parallel ports for this in the PC space but those are long gone.)
Or: If a person needs or wants a well-tuned system that they can just download and use specialized images for and write to a MicroSD card, then: A Raspberry Pi can become desirable.
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For instance: I use a Pi 4 to play movies with over SMB. I could do that a thousand or more different ways, but using LibreElec on a Pi 4 is the easiest way for me to get there -- just download it, stuff it into an SD card, and boot it up. It becomes an appliance, and this appliance is similar or identical to many other appliances; this makes supporting it easy. (And if I want to do something different with that hardware today, it takes only a few seconds to swap its storage for something completely different -- and swap it back later.)
Or: 3D printing. I can do what many others have done before me and sneaker-net gcode from the PC to the printer, or I can use a Raspberry Pi and a standardized Octoprint image to put that printer on the network instead. Now my printer is a network appliance.
The official Raspberry Pi New page has a least a few featured projects every week: https://www.raspberrypi.com/news/
The MagPi has articles and a whole monthly magazine on various projects and use cases: https://magpi.raspberrypi.com
Currently running virtual machines: * Home Assistant (https://home-assistant.io/) - with USB passthrough of USB stick to read out my digital electricity/gas meters, Zigbee and Z-Wave * Homebridge (to allow my Eufy video doorbell to work with Homekit) * Pihole
All are running from iSCSI storage served by my Synology NAS.
I am running an older Pi (3) on demand in my garden as a client for my media server to play music on garden speakers.
But IMHO, no one should be running a NAS without ECC at this point. It's on the "my RAID doesn't scrub the disks" level; it's just begging for silent disk corruption that propagates its way through backups and is impossible to fix with software solutions.
Arduino? You mean the ide or the actual hardware? It's been superceded by esp32.
They have a touch screen, speakers, and control the lights via gpio. I use the same thing to set timers, play the internet radio in the morning to wake me up, and put the lights off.
IP KVM as with the Pi KVM.
It utilizes the CSI interface for the capture without needing to do it through USB or expensive PCIe addon cards like a normal PC, the USB OTG is used to act as keyboard/mouse/disc drive/usb ethernet, the GPIO is used to control the motherboard power/reset pins, the serial pins are used to provide a console interface in case you need to reconfigure the static IP, some other pins are used to drive a small LCD display telling you the IP and status of the device, the Ethernet and Wi-Fi give connectivity options to access the local webpage where the hardware accelerated encode helps stream the data to you. The local uSD storage is plenty for storing the local ISO images and it's a full Arch Linux system in case you ever need to do anything else (like wget an image directly to the device remotely).
Not only is the hardware extremely well suited (capture, the IO pins, the decoder, the network interfaces, the minimal storage) to the exact use case but it's used in a way that doesn't really make sense to use an Arduino and would cost a lot more (in dollars, power, and space) to get a standard mini PC to do these things.
Of course I've owned 6 Raspberry Pi boards over the last 12 years and this is the only one I ever found to be worthwhile. The others were just for the novelty.