Automated Drink Dispenser With Light & Sound Feedback

This project is an automated drink dispenser built on a wheeled tank platform. It features 3 large cups and 1 water tank as liquid reservoirs, 4 mini submersible pumps that move liquid through silicone tubes into a cup, and NeoPixel LED strips for robot feedback output.

Press one of 5 buttons to choose your drink — the machine handles the rest. When dispensing is complete, the LEDs flash and a melody plays to let you know your drink is ready.

Available drinks:

White Monster
Apple Juice
Caffeine Bomb (Monster + Coffee)
Caffe Americano
Mineral Water

Built on a Raspberry Pi Pico 2W running CircuitPython, with 4 pumps controlled via an L298N motor driver, NeoPixel strips for visual feedback, and an MP3 speaker for audio notification.

Downloads

drink dispenser.MOV

Supplies

Raspberry Pi Pico 2W ×1 https://www.adafruit.com/product/6315
L298N Motor Driver Board ×2 https://www.amazon.com/HiLetgo-Controller-Stepper-H-Bridge-Mega2560/dp/B07BK1QL5T
Mini submersible aquarium pump (5V) ×4 https://www.amazon.com/ALAMSCN-Submersible-Aquariums-Fountain-Hydroponics/dp/B08PBQ1N1G
NeoPixel LED Strip ×2 https://www.adafruit.com/product/2538
Small buttons ×5 https://www.adafruit.com/product/1010
Mono Enclosed Speaker - 3W 4Ohm ×2 https://www.adafruit.com/product/3351
Food-safe silicone tubing 5mm ID ×1 https://www.amazon.com/Quickun-Silicone-Tubing-Flexible-Transfer/dp/B0852J5JQJ
Dupont jumper wires

non-electronic parts

Any liquid container

Hot glue + zip ties

1/8th inch birch wood laser cut parts

3D printed movable wheel

Downloads

ZTQ-15+v4_3+A1+mini(2).3mf

Building the Structure

Design the Laser-cut enclosure

Design a hexagonal box using Boxes.py — it's free and generates ready-to-cut SVG files automatically. Add cutouts for 5 buttons, a USB-C cable hole, and a speaker grille pattern on one face before cutting.

3D Print the wheels that is going to be on the machine and paste it onto the hexagonal box using hot glue

Solder the Buttons

Solder pin-to-pin wires onto each of the 5 buttons. For each button — one end is connected to ground and one end is connected to signal. Once soldered, push each button through its hole on the button mounting plate from the inside and secure it using hot glue.

Wire the L298N Motor Driver

Connect two L298N boards to the Pico 2W and pumps as shown below.

Wire Buttons and NeoPixels

Upload the Code

import board, time, digitalio, neopixel, pwmio

from adafruit_led_animation.color import BLACK, RED, BLUE, GREEN, YELLOW

BLACK = (0, 0, 0)

RED = (180, 0, 0)

BLUE = (0, 80, 200)

GREEN = (0, 160, 30)

YELLOW = (200, 180, 0)

CAPYBARA = (180, 120, 40)

BUTTON_PINS = [board.GP0, board.GP1, board.GP2, board.GP3, board.GP4]

BUTTON_COLORS = [RED, BLUE, CAPYBARA, GREEN, YELLOW]

DRINK_NAMES = ["Monster", "Apple Juice", "Caffeine Bomb", "Americano", "Water"]

PUMP_PINS = [

(board.GP10, board.GP11),

(board.GP12, board.GP13),

(board.GP18, board.GP19),

(board.GP20, board.GP21),

]

RECIPES = [

(True, False, False, False),

(False, False, True, False),

(True, False, False, True),

(False, False, False, True),

(False, True, False, False),

]

DISPENSE_TIME = 10

NEO_TOP_PIN = board.GP16

NEO_BOT_PIN = board.GP17

NEO_TOP_COUNT = 30

NEO_BOT_COUNT = 30

SPEAKER_PIN = board.GP14

buttons = []

for pin in BUTTON_PINS:

b = digitalio.DigitalInOut(pin)

b.switch_to_input(pull=digitalio.Pull.UP)

buttons.append(b)

pumps = []

for (pin_a, pin_b) in PUMP_PINS:

a = digitalio.DigitalInOut(pin_a)

a.direction = digitalio.Direction.OUTPUT

a.value = False

b = digitalio.DigitalInOut(pin_b)

b.direction = digitalio.Direction.OUTPUT

b.value = False

pumps.append((a, b))

neo_top = neopixel.NeoPixel(NEO_TOP_PIN, NEO_TOP_COUNT, brightness=0.5, auto_write=False)

neo_bot = neopixel.NeoPixel(NEO_BOT_PIN, NEO_BOT_COUNT, brightness=0.5, auto_write=False)

neo_top.fill(BLACK); neo_top.show()

neo_bot.fill(BLACK); neo_bot.show()

speaker = pwmio.PWMOut(SPEAKER_PIN, frequency=440, duty_cycle=0, variable_frequency=True)

def all_pumps_off():

for (a, b) in pumps:

a.value = False; b.value = False

def start_pump(index):

pumps[index][0].value = True

pumps[index][1].value = False

def dispense(drink_index):

recipe = RECIPES[drink_index]

print(f"Dispensing: {DRINK_NAMES[drink_index]}")

for i, active in enumerate(recipe):

if active:

start_pump(i)

time.sleep(DISPENSE_TIME)

all_pumps_off()

def play_tone(freq, duration):

speaker.frequency = freq

speaker.duty_cycle = 2000

time.sleep(duration)

speaker.duty_cycle = 0

time.sleep(0.04)

def dim(color, factor=3):

return tuple(min(255, c // factor) for c in color)

def celebration(color):

melody = [(523,0.12),(659,0.12),(784,0.12),(1047,0.12),(784,0.08),(1047,0.35)]

for freq, dur in melody:

for j in range(NEO_BOT_COUNT):

neo_bot.fill(BLACK)

neo_bot[j] = color

neo_bot[(j+1) % NEO_BOT_COUNT] = dim(color, 2)

neo_bot.show()

time.sleep(dur / NEO_BOT_COUNT)

play_tone(freq, dur)

for _ in range(4):

neo_bot.fill(color); neo_bot.show(); time.sleep(0.15)

neo_bot.fill(BLACK); neo_bot.show(); time.sleep(0.1)

def read_button():

for i, b in enumerate(buttons):

if b.value == False:

return i

return None

all_pumps_off()

print("Robot Coffee Maker ready!")

while True:

pressed = read_button()

if pressed is not None:

color = BUTTON_COLORS[pressed]

time.sleep(0.3)

neo_top.fill(color); neo_top.show()

dispense(pressed)

celebration(color)

neo_top.fill(BLACK); neo_top.show()

neo_bot.fill(BLACK); neo_bot.show()

print("Ready for next drink!")

time.sleep(0.05)

Troubleshooting

Pump not spinning:

Check L298N red LED is on (power OK)
Check ENA and ENB jumpers are still on the L298N board
Test with minimal code: set IN1=True, IN2=False for 5 seconds
If spinning backwards, swap OUT1 and OUT2 wires on that pump

Water looks oily:

New pumps have factory lubricant — flush with clean water 2-3 times before use
If oiliness persists, label drinks as display only

Buttons not working:

External buttons use Pull.UP — reads False when pressed
Check SW (NO) → GPIO, SW (COM) → GND
Run button test: print(button.value) in a loop

Speaker too loud:

Lower duty_cycle value from 2000 to 500-1000