The three building blocks

Here's a pattern you'll see in almost every product. Once you spot it, you can break down anything.

Input → Brain → Output

• Input — how the product senses the world. A button, or a sensor: temperature, motion, light, distance, moisture.
• Brain — a microcontroller: a tiny, cheap computer (like an ESP32 or an Arduino Nano) running a small program. It reads the inputs and decides what to do.
• Output — how the product acts on the world. An LED, a buzzer, a screen, a motor, a relay.

Back to the night light

• Light sensor → input ("it's dark")
• Controller → brain ("dark? turn the light on")
• LED → output (light)

That's it. A doorbell, a thermostat, a soil-moisture alarm — all the same three blocks, just with different sensors and outputs. When you plan a product, ask: what should it sense, what should it decide, and what should it do?

Forge doesn't invent these blocks from scratch every time — it has a library of ready, proven building blocks and picks the ones that fit your product.

A taste of what's in there:

Inputs (senses)

• A DHT22 temperature + humidity sensor
• An HC-SR04 ultrasonic distance sensor
• A PIR motion sensor
• A simple push button

Brains (decides)

• ESP32 — a capable controller with built-in WiFi
• Arduino Nano — small and simple

Outputs (acts)

• An OLED screen
• A NeoPixel addressable RGB LED
• A buzzer
• A relay to switch something big (a lamp, a pump)

When you describe a product, Forge chooses matching blocks from this library and wires them correctly — the right sensor on the right pins, the right power for each. Your job is to describe clearly what the product should sense and do. The clearer the description, the better the first design.

Let's build the classic input → brain → output product: sense the temperature, show it on a screen.

Send the prompt and watch Forge pick a temperature sensor (input), a controller (brain), and an OLED screen (output) — then assemble them into a working design with a parts list.

As you read its answer, play spot-the-blocks: which part is the input, which is the brain, which is the output?