Hub Outputs¶

Pybrick Documentation

All Pybricks commands are listed in the Pybricks documentation. You can also find it in the right-hand panel of the Pybricks IDE.

The Spike Prime Hub has three ways to produce output:

Hub status light
Light matrix
Speaker

Output and Input

Think of a robot exploring a room on its own.

When it uses sensors to detect a wall ahead — that’s input. The robot is collecting information.

When it turns left to avoid the wall — that’s output. The robot is acting on that information.

Input = gathering information. Output = doing something with it.

The Hub Status Light¶

The status light sits around the power button. By default it is turned off.

Hub Status Light

Status Light Functions¶

Function	What it does
`light.on(color)`	Turns the light on at a chosen colour
`light.off()`	Turns the light off
`light.blink(color, durations)`	Blinks the light on and off at set time intervals
`light.animate(colors, interval)`	Cycles through a list of colours, one at a time

Status Light Example¶

Create a new file called hub_light.py
Type the code below into the file
Predict what you think will happen
Run your code

from pybricks.hubs import PrimeHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor, ForceSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch

# --- SETUP
# start components
hub = PrimeHub()

# store variables

# --- RUNNING
while True:
    # read sensor data

    # process data

    # output data
    hub.light.on(Color.MAGENTA)
    wait(1000)
    hub.light.blink(Color.RED, [500,250,500,250])
    wait(1500)
    hub.light.animate([Color.GREEN, Color.WHITE, Color.ORANGE],1000)
    wait(3000)
    hub.light.off()
    wait(1000)

Investigate

lines 3–7 → imports all Pybricks commands for your robot
lines 9–10 → creates a PrimeHub object and names it hub
line 14 → starts an endless loop
line 15 → sets the status light to MAGENTA
- see the colour documentation for all available colours
line 16 → waits 1000 milliseconds (1 second)
line 17 → blinks RED: on 500ms → off 250ms → on 500ms → off 250ms
line 18 → waits 1500 milliseconds
line 19 → animates through GREEN, WHITE, then ORANGE, each showing for 1000ms
line 20 → waits 3000 milliseconds
line 21 → turns the light off
line 22 → waits 1000 milliseconds

Modify

Can you display different colours?
Can you change the timing of the blink?
Can you change the timing of the animation?
What happens if you put a # in front of all the wait lines to comment them out?

Light Matrix¶

The hub has a 5×5 grid of lights called the light matrix. You can display text, icons, or control individual pixels using their row and column coordinates.

light matrix

Light Matrix Functions¶

Function	What it does
`display.orientation(up)`	Sets which side of the hub is considered “up”
`display.off()`	Turns off all pixels
`display.pixel(row, column, brightness=100)`	Turns on a single pixel at a set brightness
`display.icon(icon)`	Displays a built-in icon — see the full icon list
`display.animate(matrices, interval)`	Plays an animation using a list of icons
`display.number(number)`	Displays a number from −99 to 99
`display.char(char)`	Displays a single character or symbol
`display.text(text, on=500, off=50)`	Scrolls a text string, one character at a time

Light Matrix Example¶

Create a new file called light_matrix.py
Type the code below into the file
Predict what you think will happen
Run your code

from pybricks.hubs import PrimeHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor, ForceSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop, Icon
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch

# --- SETUP
# start components
hub = PrimeHub()

# store variables

# --- RUNNING
while True:
    # read sensor data

    # process data

    # output data
    hub.display.orientation(Side.RIGHT)
    hub.display.icon(Icon.UP)
    wait(250)
    hub.display.orientation(Side.BOTTOM)
    hub.display.icon(Icon.UP)
    wait(250)
    hub.display.orientation(Side.LEFT)
    hub.display.icon(Icon.UP)
    wait(250)
    hub.display.orientation(Side.TOP)
    hub.display.icon(Icon.UP)
    wait(250)

    hub.display.off()
    wait(500)

    hub.display.pixel(1,1,100)
    hub.display.pixel(1,3,100)
    hub.display.pixel(3,1,100)
    hub.display.pixel(3,2,100)
    hub.display.pixel(3,3,100)
    wait(1000)

    hub.display.off()
    wait(500)

    arrows = [Icon.RIGHT, Icon.DOWN, Icon.LEFT, Icon.UP]
    hub.display.animate(arrows, 500)
    wait(1000)

    hub.display.off()
    wait(500)

    hub.display.char("R")
    wait(500)
    hub.display.number(2)
    wait(500)
    hub.display.char("D")
    wait(500)
    hub.display.number(2)
    wait(500)

    hub.display.off()
    wait(1000)

    hub.display.text("C3PO", 500, 50)

    hub.display.off()
    wait(2000)

Investigate

lines 3–7 → imports all Pybricks commands — make sure Icon is included at the end of line 5
lines 9–10 → creates a PrimeHub object and names it hub
line 15 → starts an endless loop
lines 16–27 → rotates the display orientation and shows an up arrow for each direction
lines 29–30 → turns the display off for 1 second
lines 32–37 → lights up individual pixels to draw a “meh” face
lines 38–40 → turns the display off for 1 second
line 42 → creates a list of icons
line 43 → animates through each icon in the list, showing each for 500ms
line 44 → waits 1 second
lines 46–47 → turns the display off for 1 second
lines 49–56 → displays numbers and characters one at a time
lines 58–59 → turns the display off for 1 second
line 61 → scrolls the text C3PO across the display
lines 63–64 → turns the display off for 2 seconds

Modify

Can you make Icon.HAPPY spin around all four display orientations?
Can you redesign the “meh” face so the mouth fills the whole bottom row and the eyes are 2×2 pixels?
What happens if you comment out all the wait lines?

Speaker¶

The hub has a built-in speaker for playing tones and music.

Speaker Functions¶

Function	What it does
`speaker.volume(volume)`	Sets the volume level. If no value is given, returns the current volume
`speaker.beep(frequency=500, duration=100)`	Plays a single beep at a given pitch and length
`speaker.play_notes(notes, tempo=120)`	Plays a sequence of musical notes at a set tempo

Speaker Example¶

Create a new file called speaking.py
Type the code below into the file
Predict what you think will happen
Run your code

from pybricks.hubs import PrimeHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor, ForceSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch

# --- SETUP
# start components
hub = PrimeHub()

# store variables

# --- RUNNING
while True:
    # read sensor data

    # process data

    # output data
    hub.speaker.volume(100)
    current_volume = str(hub.speaker.volume())
    hub.display.text(current_volume)
    hub.speaker.beep(440,500)
    
    hub.speaker.volume(50)
    current_volume = str(hub.speaker.volume())
    hub.display.text(current_volume)
    hub.speaker.beep(440,500)
    
    oh_when_the_saints = [
        "C4/4", "E4/4", "F4/4", "G4/1",
        "C4/4", "E4/4", "F4/4", "G4/1",
        "C4/4", "E4/4", "F4/4", "G4/2",
        "E4/2", "C4/2", "E4/2", "D4/1",
        "E4/4", "E4/4", "D4/4", "C4/2",
        "C4/2", "E4/2", "G4/4", "G4/4", "G4/4", "F4/1",
        "E4/4", "F4/4", "G4/2", "E4/2", "C4/2", "D4/2", "C4/1"
    ]

    hub.speaker.play_notes(oh_when_the_saints,180)

Investigate

lines 3–7 → imports all Pybricks commands for your robot
lines 9–10 → creates a PrimeHub object and names it hub
line 15 → starts an endless loop
line 17 → sets the volume to 100%
lines 18–19 → reads the current volume and displays it on the light matrix
line 20 → plays a 440Hz beep for 500ms
line 22 → sets the volume to 50%
lines 23–24 → reads the current volume and displays it on the light matrix
line 25 → plays a 440Hz beep for 500ms
lines 27–35 → stores the notes for Oh When the Saints in a list
line 37 → plays the notes at 180 BPM

Modify

What is the lowest volume you can still hear?
What is the lowest pitch beep you can hear?
What is the highest pitch beep you can hear?
Can you program the hub to play a different tune?