Buddybox

At a glance

Printed parts

13

Difficulty

Intermediate: basic soldering

Build time

about 2 h

Parts checklist

Printed parts

Electronics

• ESP32-S3 DevKitC-1 N16R8, dual USB-C check your board’s USB power path
• INMP441 I2S microphone 3V3 only
• MAX98357A I2S amplifier, screw terminal "MAX98357A I2S amplifier breakout"
• 40 mm speaker, 8 Ω (about 2–3 W is plenty) "40mm speaker 8 ohm"
• KY-040 rotary encoder with nut "KY-040 rotary encoder module"
• MX-style switch, any MX-compatible switch "Cherry MX compatible switch"
• 8x8 WS2812(B) matrix, about 68 × 66 mm "WS2812B 8x8 LED matrix"

Fasteners

Screws thread straight into printed pilot holes. Use socket head screws. No inserts, magnets or glue.

Supplied wire and buyer tools

• Supplied F-F Dupont jumpers, ~10 cm (mic, amp, encoder)
• Supplied thin stranded wire or Dupont jumpers (switch, matrix)
• Supplied heat-shrink tubing
• Soldering iron and solder
• Small screwdrivers / hex keys
• Flush cutters
• Tweezers
• USB-C data cable

Wiring

Every module goes straight to the S3, no breadboard. Check your board’s silkscreen first, because some clones swap the header rows.

Assembly

1. 1Prepare the electronics

   • Identify the USB-to-5Vin power path for your exact S3 board before changing any jumper. Keep USB disconnected while soldering or wiring.
   • Solder header pins on the mic and amp if needed, so they take Dupont jumpers.
   • The KY-040 has header pins: it plugs in with Dupont jumpers, no soldering.
   • Solder wires to both MX switch legs and the matrix input (DIN, 5V, GND). Cut them to fit, about 10–15 cm, long enough to reach the S3 with the lid off.
   • Screw the speaker leads into the amp’s + / − terminal.
   Tip Flash your firmware now (see below) and test everything on the bench before closing the box.

2. 2Speaker, deck and modules

   

   Screws 2× M2 (amp)

   • Lay the 40 mm speaker cone down on the base over the hole field and drop the speaker ring over it.
   • Put the S3 on its back in the deck, pins and plugs up, USB-C toward the back slot.
   • Screw the amp onto its two deck posts.
   • Set the deck on the base posts.

   Electronics are drawn as simple blocks: green = boards. The speaker is hidden under the deck.

3. 3Microphone and body

   Screws 2× M2×4–6 (mic) · 4× M3×6 (base)

   • Screw the mic onto its two posts behind the front grille, inside the body. The mic hole faces the grille.
   • Lower the body over the base and deck. Fix the base with 4× M3×6 from the sides.
   • Plug the mic and amp jumpers onto the S3.

4. 4Lid underside: switch, encoder, hinge

   

   Screws 2× M3×5 · 2× M3×6 · 2× M3×10

   • Clip the MX switch into the switch bracket, clips facing left and right. Screw it on from the top of the lid with 2× M3×5. The tonearm hides these screws.
   • Put the KY-040 in the encoder bracket, shaft up, and clamp it with its own nut. Screw it on from the top with 2× M3×6, under where the knob goes.
   • Screw the hinge onto the top of the lid with 2× M3×10, from inside the lid up into the lugs.

   Blue = KY-040, grey = MX switch.

5. 5Close the box

   Screws 4× M3×8

   • Plug the encoder jumpers onto the S3 and wire the switch. Route the matrix cable through the plinth’s rear notch and USB slot and connect it while the lid is open.
   • Check every connection against the wiring table. Confirm the lid holes align, the cable has enough slack and no lead is trapped. Set the lid on the body and screw it down at the corners.

6. 6Stem cap, tonearm, ring and knob

   

   Screws supplied pivot pin

   • Press the stem cap onto the MX switch stem.
   • Set the tonearm between the hinge lugs, headshell over the stem cap. Push the supplied pivot pin through the outer lug and the hub into the tight far lug until seated.
   • Drop the grooved ring over the encoder shaft onto the lid.
   • Push the record knob onto the D-shaft.

   

7. 7Plinth and feet

   

   Screws 4× rubber feet

   • Lay the 8x8 matrix in the plinth, LEDs facing down. It rests on the inner ledges, 6 mm above the floor; no glue or tape needed.
   • Seat the cable in the rear notch using the route prepared before closing the lid. Check that it is not stretched or pinched.
   • Stick the feet under the plinth and stand the box in the plinth’s collar.

   

Make it yours: firmware

Buddybox ships without firmware. The hardware is a standard ESP32-S3 with an I2S mic, an I2S amp, a rotary encoder, a button (the tonearm switch) and the supplied LED matrix, so you can write your own. Two ways:

Option A: ESPHome + Home Assistant (no code)

1. Install ESPHome: the ESPHome Device Builder add-on in Home Assistant, or pip install esphome on a computer.
2. Create a new ESP32-S3 device and replace its YAML with the skeleton below. Keep Wi-Fi passwords and keys in ESPHome’s secrets.yaml, never in a file you share.
3. Flash over USB first (the S3’s native USB-C port), then update over Wi-Fi.
4. In Home Assistant, adopt the device under Settings › Devices & services › ESPHome with its API key.
5. Voice: under Settings › Voice assistants, create an Assist pipeline and select it on the device. The tonearm starts listening.
6. Controls: the knob and buttons appear as entities. Use them in automations for volume, scenes or media.

Minimal skeleton, written for this guide. Adjust it and check the ESPHome docs for your version. Add a media_player (speaker platform) to play music or announcements on it.

esphome:
  name: buddybox
  on_boot:
    priority: 800
    then:
      - output.turn_off: mic_lr      # mic L/R must be LOW (left channel)
      - output.turn_off: button_gnd  # the switch's second leg acts as ground

esp32:
  board: esp32-s3-devkitc-1
  framework:
    type: esp-idf

logger:
api:
  encryption:
    key: !secret api_key
ota:
  - platform: esphome
    password: !secret ota_password
wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

output:
  - platform: gpio
    id: mic_lr
    pin: GPIO7
  - platform: gpio
    id: button_gnd
    pin: GPIO14

i2s_audio:
  - id: i2s_in
    i2s_lrclk_pin: GPIO5
    i2s_bclk_pin: GPIO4
  - id: i2s_out
    i2s_lrclk_pin: GPIO16
    i2s_bclk_pin: GPIO15

microphone:
  - platform: i2s_audio
    id: mic
    i2s_audio_id: i2s_in
    i2s_din_pin: GPIO6
    adc_type: external
    channel: left

speaker:
  - platform: i2s_audio
    id: amp
    i2s_audio_id: i2s_out
    i2s_dout_pin: GPIO17
    dac_type: external

voice_assistant:
  microphone: mic
  speaker: amp

sensor:
  - platform: rotary_encoder
    name: Knob
    pin_a: { number: GPIO10, mode: INPUT_PULLUP }
    pin_b: { number: GPIO11, mode: INPUT_PULLUP }

binary_sensor:
  - platform: gpio
    name: Knob button
    pin: { number: GPIO12, mode: INPUT_PULLUP, inverted: true }
  - platform: gpio
    name: Tonearm
    pin: { number: GPIO13, mode: INPUT_PULLUP, inverted: true }
    on_press:
      - voice_assistant.start:
    on_release:
      - voice_assistant.stop:

light:
  - platform: esp32_rmt_led_strip
    name: Glow
    pin: GPIO8
    num_leds: 64
    rgb_order: GRB
    chipset: WS2812
    color_correct: [10%, 10%, 10%]   # start with a low brightness

Option B: build it with an AI coding assistant

Any AI coding assistant can draft firmware (ESPHome YAML, Arduino or ESP-IDF) from a clear hardware description. Paste this and adapt the last paragraph:

I built a desk device on an ESP32-S3 DevKitC-1 (N16R8, 16 MB flash, octal PSRAM).
Hardware and pins:
- INMP441 I2S microphone: SCK GPIO4, WS GPIO5, SD GPIO6, L/R on GPIO7 (drive LOW), VDD 3V3
- MAX98357A I2S amplifier: BCLK GPIO15, LRC GPIO16, DIN GPIO17, VIN 5V; 40 mm speaker
- KY-040 rotary encoder: CLK GPIO10, DT GPIO11, SW GPIO12 (push button), + 3V3
- Push button (MX switch): one leg GPIO13, the other leg GPIO14 (drive LOW as ground)
- 8x8 WS2812 LED matrix: DIN GPIO8, powered from USB 5V (start with low brightness; match the panel’s data-level requirements)
Mic and amp are on separate I2S buses.
Write ESPHome YAML for Home Assistant: hold the button to talk to the voice assistant,
turn the knob for volume, click it to play/pause, and show a colour on the matrix
while listening. Keep Wi-Fi and keys in secrets.yaml.

Ideas

• Push-to-talk voice assistant for Home Assistant: lights, timers, questions.
• Music remote: knob for volume, click to play/pause, double click to skip.
• Scene dial: turn to pick a scene, click to apply; the glow shows the colour.
• Timer: turn to set minutes, click to start, a chime when it ends.
• Status light: the plinth glows for the doorbell, a finished washing machine or a calendar event.