Buggy Battle

Goal: Press button A on the remote — buggy drives forward for 1 second, then stops.

Concepts: radio.send, radio.receive, motor on/off.

Goal: A = left, B = right, A+B = forward, no button = stop.

Concepts: polling buttons, multiple commands, default-stop logic.

// REMOTE (sender)
on start
  radio set group 1

forever
  if (button A is pressed) AND (button B is pressed)
    radio send string "F"
  else if button A is pressed
    radio send string "L"
  else if button B is pressed
    radio send string "R"
  else
    radio send string "S"
  pause 100 ms

// BUGGY (receiver)  -- requires the "kitronik-motor-driver" extension
on start
  radio set group 1

on radio received receivedString
  if receivedString = "F"
    Motors: motor 1 forward at 100
    Motors: motor 2 forward at 100
  else if receivedString = "L"
    Motors: motor 1 reverse at 80
    Motors: motor 2 forward at 80
  else if receivedString = "R"
    Motors: motor 1 forward at 80
    Motors: motor 2 reverse at 80
  else
    Motors: motor 1 off
    Motors: motor 2 off

# remote.py  --  the handheld micro:bit
from microbit import *
import radio

radio.config(group=1)
radio.on()

last = ""
while True:
    if button_a.is_pressed() and button_b.is_pressed():
        cmd = "F"
    elif button_a.is_pressed():
        cmd = "L"
    elif button_b.is_pressed():
        cmd = "R"
    else:
        cmd = "S"

    if cmd != last:          # only send on change -> less radio traffic
        radio.send(cmd)
        last = cmd
    sleep(50)

# buggy.py  --  the micro:bit on the motor board
from microbit import *
import radio

radio.config(group=1)
radio.on()

# Kitronik 5620 motor pins
M1F, M1R = pin8, pin12    # left motor:  forward, reverse
M2F, M2R = pin0, pin16    # right motor: forward, reverse
SPEED = 1023              # 0-1023 (PWM). Lower = slower.

def drive(lf, lr, rf, rr):
    M1F.write_analog(lf); M1R.write_analog(lr)
    M2F.write_analog(rf); M2R.write_analog(rr)

def stop():    drive(0, 0, 0, 0)
def forward(): drive(SPEED, 0, SPEED, 0)
def left():    drive(0, SPEED, SPEED, 0)
def right():   drive(SPEED, 0, 0, SPEED)

stop()
while True:
    msg = radio.receive()
    if   msg == "F": forward()
    elif msg == "L": left()
    elif msg == "R": right()
    elif msg == "S": stop()
    sleep(20)

Goal: Hold the remote like a steering wheel. Tilt forward = drive, tilt left/right = turn.

Concepts: accelerometer, mapping ranges, dead zones.

# remote.py  --  Stage 3 (tilt)
from microbit import *
import radio

radio.config(group=1)
radio.on()

last = ""
while True:
    x = accelerometer.get_x()      # -1024 (left) .. +1024 (right)
    y = accelerometer.get_y()      # -1024 (forward) .. +1024 (back)

    if abs(x) < 200 and abs(y) < 200:
        cmd = "S"                  # dead zone -- otherwise it never stops
    elif y < -300:
        cmd = "F"
    elif x < -300:
        cmd = "L"
    elif x > 300:
        cmd = "R"
    else:
        cmd = "S"

    if cmd != last:
        radio.send(cmd)
        last = cmd
    sleep(50)

Goal: Add features for the sumo event — horn (buzzer), headlights, and a "boost" turbo button.

Concepts: additional commands, output devices, variable speed.

• Boost: press logo / shake to send "B" → buggy uses higher PWM for 1 second.
• Horn: on receiver play a tone via music.pitch() on a free pin.
• Headlights: use the micro:bit display: scroll ↑ arrows when driving forward.
• Reverse: add a "V" command (e.g. shake), needed when sumo opponents wedge in.