A Raspberry Pi is a whole little computer on a single board. Unlike the ESP32, it runs a real operating system (Linux), so it can do the jobs a microcontroller cannot: run software, store a lot of data, serve a website, handle a camera, and host the hub that all your sensors report to. In an Open Agriculture Technology setup the Pi is usually the brain in the middle. The cheap microcontroller nodes do the sensing out in the field, and the Pi runs Home Assistant, keeps the history, and runs the automations.
What it is.
Where the ESP32 is a microcontroller, the Raspberry Pi is a small Linux computer about the size of a deck of cards. It has a real processor with several cores, gigabytes of memory, USB ports, video output, networking, and a row of pins for talking to electronics. It boots an operating system from an SD card or an SSD, and from there it runs ordinary software: a database, a web server, Home Assistant, a camera pipeline. It costs more than a microcontroller and uses more power, and in return it does far more.
A computer, not a microcontroller.
This is the distinction worth getting right, because it decides which board you reach for. A microcontroller like the ESP32 runs one fixed program, starts instantly, sips power, and is happy bolted to a bench reading a sensor for years. A Raspberry Pi runs a full operating system, which means it can do many things at once and run real software, but it also takes time to boot, needs steady power, and is not the thing you leave on a battery in a far corner of a field. Use the microcontroller for the cheap, rugged, single-purpose nodes. Use the Pi for the jobs that need a real computer.
The hub of the system.
This is where the Pi shines, and where it ties the whole workshop together. A single board can run on its own as a small computer doing one job, such as logging a camera or serving a dashboard. More often, though, it is the hub of a system: the place every sensor node reports to.
The system we embrace here is Home Assistant, and a Raspberry Pi is the classic board to run it on. Home Assistant lives on the Pi, gathers the readings your ESP32 nodes push to it (often through ESPHome), draws the graphs, stores the history, and runs the automations, and every reading stays yours to keep and export. Home Assistant is one option we like, not the only one; the same Pi will just as happily run an MQTT broker, a database, or Node-RED. The shape stays the same: cheap microcontrollers at the edge, one small computer as the brain.
Microcontroller or Raspberry Pi.
They are different tools, and most real setups use both. The table is the quick way to see which job belongs to which board.
| By the job | Microcontroller (ESP32) | Linux computer (Raspberry Pi) |
|---|---|---|
| Runs an operating system | No, one program | Yes, Linux |
| Starts up in | An instant | About 20 to 30 seconds |
| Idle power | Milliwatts; microamps asleep | A few watts |
| Typical price | A few dollars | Tens of dollars and up |
| Storage | A few MB | microSD or SSD, many GB |
| Analog inputs | Yes, built in | No, needs an add-on |
| Exact timing | Yes | No (Linux is not real-time) |
| Runs Home Assistant | No, it reports to it | Yes, it hosts it |
| Best for | Cheap field sensor and control nodes | The hub: software, storage, cameras |
The Raspberry Pi’s pins are 3.3 V and, like the ESP32’s, are not 5 V tolerant. Unlike the ESP32, the Pi has no built-in analog input; an add-on chip handles analog sensors when you need them.
Which model.
The line runs from tiny and cheap to small-desktop fast. Three cover almost every grower need:
For a Home Assistant hub on a typical farm, a Raspberry Pi 4 or 5 is the comfortable choice.
Where it fits, and where it doesn’t.
Where it fits
- Running Home Assistant as the hub of your setup.
- Storing history in a database you own.
- Cameras, vision, and dashboards at the edge.
- Any job that needs a real operating system on site.
Where it doesn’t
- Cheap, battery-powered field nodes. Use an ESP32.
- Exact, real-time timing. A microcontroller is the right tool.
- Direct analog sensors, without an add-on converter.
- Anywhere it cannot get steady power.
How you set one up.
Because the Pi runs an operating system, you do not flash a single program onto it. You install software, the way you would on any computer:
- Raspberry Pi Imager: writes an operating system to an SD card or SSD from your computer. The first step every time.
- Home Assistant OS: a ready-made image that turns a Pi into a dedicated Home Assistant hub. Often the only software a grower needs to install.
- Raspberry Pi OS: the general-purpose Linux system, for running your own mix of databases, scripts, and services.
Buying and gotchas.
- Buy a proper power supply. Underpowering a Pi causes mysterious crashes. The Pi 5 in particular wants a 5 V supply rated for its higher current.
- Use a good SD card, or an SSD. Cheap cards wear out and corrupt. A quality card, or an SSD on the Pi 4 and 5, is far more reliable for a hub that runs around the clock.
- No built-in analog. The Pi cannot read an analog sensor directly. Add a small converter chip, or put the analog sensor on an ESP32 and let it report in.
- Not real-time. Linux is not built for clock-perfect timing. For steppers, pulses, or tight loops, use a microcontroller.
- 3.3 V pins. Like the ESP32, the GPIO header is 3.3 V and not 5 V tolerant.
- Give it real power and cooling under load. A busy Pi 5 runs warm; a heatsink or fan keeps it steady.
Official resources.
These open in a new tab:
Raspberry Pi: all models Raspberry Pi Imager Install Home Assistant Documentation
Frequently asked questions.
What is a Raspberry Pi?
It is a small, low-cost computer on a single board that runs Linux. It can run real software, store data, handle cameras, and host a hub like Home Assistant, which is what sets it apart from a microcontroller such as the ESP32.
What is the difference between a Raspberry Pi and an ESP32?
A Raspberry Pi is a full Linux computer; an ESP32 is a microcontroller. The Pi runs software and hosts the hub. The ESP32 is cheap, low-power, and made for reading a sensor or switching an output. Many setups use both: ESP32 nodes in the field, a Pi as the brain.
Can a Raspberry Pi run Home Assistant?
Yes, and it is one of the most common ways to run it. Install Home Assistant OS with the Raspberry Pi Imager and the Pi becomes a dedicated hub that gathers readings from your sensor nodes, stores their history, and runs automations. All the data stays on the Pi, where you can read and export it.
Which Raspberry Pi should I buy for Home Assistant?
A Raspberry Pi 4 or 5 is the comfortable choice for a farm hub, with room for history and several integrations. A Raspberry Pi Zero 2 W can run a small setup if budget and size matter most.
Can a Raspberry Pi read analog sensors directly?
No. Unlike the ESP32, the Pi has no built-in analog-to-digital converter. Add a small converter chip, or connect the analog sensor to an ESP32 and let it report the reading to the Pi.
Do I need a Raspberry Pi for a farm monitoring system?
No. A microcontroller node can send its readings straight to a database or dashboard you run, with no Raspberry Pi in between. A Pi earns its place when you want a hub on site: one machine that gathers every reading, runs Home Assistant, stores the history, and keeps working when the internet goes down.