PyRaspBeta

Glossary

Every term the docs use, in plain language. On the other pages, the first time one of these words appears it links back here.

  • 1-Wire — A bus that needs one data wire plus ground. The DS18B20 thermometer uses it, on GPIO4 with a 4.7 kΩ pull-up.
  • 3V3 — The 3.3 V supply rail on the header. The Pi's GPIO logic is 3.3 V, so 3.3 V is the safe level for a GPIO pin.
  • 5V — The 5 V supply rail on the header. Motors, servos and 5 V sensors use it; 5 V on a GPIO pin damages the Pi.
  • ADC — Analog-to-digital converter. The Pi has no analog pins, so analog sensors need one: the MCP3008 over SPI, or the ADS1115 over I²C.
  • attempt — Your one timed run at a day's objective. The clock starts when you press Start and keeps running on the server.
  • baud — Serial speed, in bits per second. The GPS module sends its NMEA sentences at 9600 baud.
  • BCM pin — A GPIO named by the Broadcom chip's numbering, like GPIO17. wiring and gpiozero both use BCM numbers.
  • bill — The running cost of the parts your circuit.py has bought, shown next to the budget. Boards are free; a build over budget cannot be submitted.
  • bounce — The tiny make-and-break chatter of a mechanical switch's contacts, lasting a few milliseconds when it is pressed or released.
  • breadboard — The perforated board parts and wires are pushed into. Lab mode lets you place them on one yourself; the workspace lays your circuit out for you.
  • check — One thing an objective's tests verify, such as "the LED is on between 0.5 s and 3 s". Every check must pass for a build to be accepted.
  • CSI — Camera Serial Interface, the ribbon connector a camera module plugs into. In circuit.py, wire it with pi.CSI.
  • current — The flow of charge, measured in amperes (A). A GPIO pin should stay under about 16 mA.
  • debounce — Ignoring a switch's brief make-and-break chatter so one press counts as one press.
  • duty cycle — The fraction of each PWM period a pin is high, usually between 0 and 1. A 0.5 duty cycle is on half the time.
  • environment — An objective's fixed world: the sensor values, room state and stimuli the judge applies, so every attempt faces the same conditions.
  • floating input — An input wired to nothing, which reads an unpredictable level. Pull-ups and pull-downs give it a defined one.
  • forward voltage — The voltage a diode drops while conducting, about 2 V for a red LED. Subtract it from the supply before sizing a series resistor.
  • GND — Ground, the 0 V reference every circuit shares. In circuit.py, each pi.GND hands out a fresh ground pin.
  • GPIO — General-purpose input/output: the programmable pins on the 40-pin header, which can be inputs or outputs.
  • I²C — A two-wire bus (SDA and SCL) where every chip answers to its own address. LCDs, OLEDs, the BME280 and the ADS1115 use it.
  • kit — A finished, pre-wired shop module such as kits.LEDModule(). It costs more than its separate parts but saves the wiring.
  • Lab mode — The full simulator in the Lab tab: drag-and-drop wiring, the inspector, data feeds, instruments and projects.
  • level shifting — Converting a signal between 5 V and 3.3 V logic safely, with a voltage divider or a module.
  • module — A reusable component you define by subclassing Module: build its parts in build() and publish pins with expose().
  • NMEA — The plain-text sentence format GPS modules emit, such as $GPGGA, which pynmea2 parses.
  • Ohm's law — V = I × R: voltage equals current times resistance. It is how you pick a series resistor.
  • open-drain — A pin that can only pull a line low or leave it floating; a pull-up provides the high level. I²C lines work this way.
  • physical pin — A position on the 40-pin header, numbered 1–40. pi.pin(11) is physical pin 11, which carries GPIO17.
  • pull-down — A resistor from a pin to ground that holds an input low until something drives it high, as a button wired to 3.3 V does.
  • pull-up — A resistor from a pin to 3.3 V that holds an input high until something pulls it low, as a button wired to ground does.
  • PWM — Pulse-width modulation: switching a pin on and off quickly to dim an LED, set a motor's speed or play a tone.
  • resistance — How strongly a part opposes current, measured in ohms (Ω). A resistor is a part whose whole job is resistance.
  • sandbox — The untimed, unranked scratch workspace at /sandbox. It is where a shared build opens for editing.
  • series resistor — A resistor placed in the same loop as a part, usually an LED, to limit its current; 330 Ω is the usual value from 3.3 V.
  • SPI — A four-wire bus (SCLK, MOSI, MISO and a chip-enable pin) for fast chips such as the MCP3008 ADC.
  • UART — Asynchronous serial over a transmit and a receive pin (TXD and RXD). The GPS module talks over it.
  • verdict — The judge's answer to a submission: accepted, rejected, build-error or over-budget. A judge failure is reported as error and does not count against you.
  • voltage — The electrical push between two points, measured in volts (V). The Pi's GPIO runs at 3.3 V.
  • voltage divider — Two resistors in series that scale a voltage down, such as a 5 V sensor output to a level a 3.3 V GPIO can read.

Going deeper

These definitions are the short version. The concept primers explain the electronics properly — voltage, current and Ohm's law; pull-ups and debouncing; PWM; the buses (I²C, SPI, UART and 1-Wire); ADCs; relays; and the GPIO header itself. The wiring library pages show how each of these appears on a real part's pins, and each part page repeats the numbers that matter for that part.