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Raspberry Pi GPIO Pinout Explorer

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About This MicroSim

A printed pinout diagram is dense, and a misread pin number can destroy a board. This is the same information, but it answers the question you actually have with the Pi in your hand: which pin is this, and what happens if I connect here?

All 40 pins are clickable. Each one reports its physical number, its BCM GPIO number, its function, a safety line, and where the book uses it. Pin 1 is drawn as a square, exactly as it is silkscreened on the board.

The colours are the fast path:

  • Orange - 3.3 V power. Safe for the sensors in this book.
  • Red - 5 V. Never connect these to a GPIO pin.
  • Black - ground. There are eight of them, and any one will do.
  • Green - general-purpose GPIO.
  • Blue - GPIO with a special function: I2C, SPI or UART.

Wire the BME280 walks through the four pins the build needs, one at a time. It starts with ground, not with power, and says why: if power reaches a sensor before ground does, the return current has to find its way home through a data line.

How to Use

  • Hover any pin to highlight it. Click it to open the full detail panel.
  • Use Power, Ground and I2C to dim everything else. Non-matching pins fade rather than vanish, so you never lose track of where a pin sits.
  • Press Wire the BME280 and then Next step four times. The highlighted pin pulses yellow and the panel names the wire colour.
  • Click pin 2 or pin 4 and read the safety line before you go anywhere near the bench.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

<iframe src="https://iowerx.github.io/pi-env-monitor/sims/gpio-pinout-explorer/main.html"
        height="526px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

6-12

Duration

10-15 minutes

Bloom's Taxonomy Level

Remember (L1)

Prerequisites

  • No prior knowledge required

Activities

  1. Orientation (3 min): Find pin 1. Find pin 40. Explain how the odd and even numbers are arranged, and check it against a real board or a photograph.
  2. Exploration (6 min): Use the Ground filter. How many ground pins are there? Now use Power. How many pins carry 5 V, and what does the safety line say about them?
  3. Guided build (5 min): Run Wire the BME280 all the way through. Write down the four pin numbers and the four wire colours from memory afterwards.

Assessment

  • Locates a pin by physical number and states its function.
  • Distinguishes physical pin numbering from BCM GPIO numbering.
  • Identifies the 5 V pins as the ones never to connect to a sensor or a GPIO pin.

References

  1. Raspberry Pi documentation: GPIO - the authoritative pinout and electrical limits.
  2. pinout.xyz - the pinout reference most Pi users keep open.
  3. Bosch Sensortec BME280 datasheet - the sensor these four pins are for.
  4. Wikipedia: I2C - the two-wire bus on pins 3 and 5.