ROUTE 13

ATOM Matrix — 24 × 24mm. 25 RGB LEDs. Accelerometer. Wi-Fi. USB-C. ~$15. Pressure mat adds ~$2.

The ATOM Matrix — same board as the Swamp Glow. Everything built in except the pressure mat, which connects with two wires.

Download the firmware zip and extract it on your computer.

Connect the ATOM Matrix via USB-C. It shows up as a drive called CIRCUITPY. Copy the route-13 folder contents onto the drive. The device reboots automatically and starts running. It boots in about 2 seconds.

What happens on boot:

• The 5×5 LED grid shows a dim orange idle pattern
• The pressure mat input starts polling on GPIO 32
• Saved settings load from flash (color, brightness, pattern, trigger duration)

Wiring the mat: One mat wire to GPIO 32 (G32). Other mat wire to GND. A 10K resistor between G32 and 3V3. Three connections total. When someone steps on the mat, GPIO 32 goes LOW and the firmware triggers the display.

Hold the button for 3 seconds. The LED grid turns yellow — the ATOM Matrix is now running as a Wi-Fi access point.

The setup page is embedded in the firmware — a single HTML file served from the device. No internet needed. Dark background, orange accents, Route 13 theme. It looks like it belongs to the book.

The AP page also lets you enter Wi-Fi credentials for Step 3 — but that’s optional. You can use the device with just the AP page forever.

On the AP setup page, there’s a section for Wi-Fi credentials. Enter your network name and password. Hit save. The device reboots, connects to your Wi-Fi, and now you can reach it from any device on the same network.

With Wi-Fi, you can check the passenger count from another room. Reset the counter remotely. Change the trigger pattern. All from your browser.

If you have multiple devices on the same network — a Swamp Glow and a Route 13, for example — each one has its own IP. Bookmark them. Control any device from any browser on your network.

The ATOM Matrix runs CircuitPython with the Tick library. All the code lives on the CIRCUITPY drive. Here’s what it does:

Pressure Mat Input

The mat connects to GPIO 32 with a pull-up resistor. When someone sits down, the pin goes LOW:

import board
import digitalio

# Pressure mat on GPIO 32 with internal pull-up
mat = digitalio.DigitalInOut(board.G32)
mat.direction = digitalio.Direction.INPUT
mat.pull = digitalio.Pull.UP

def is_pressed():
    return not mat.value  # LOW when pressed

LED Display — “13” Pattern

The 5×5 grid shows “13” in orange when triggered. Each LED maps to a position on the grid:

import neopixel

NUM_LEDS = 25
np = neopixel.NeoPixel(board.G27, NUM_LEDS, auto_write=False)

# "13" on a 5x5 grid (0=off, 1=on)
PATTERN_13 = [
    0,1,0,1,1,  # row 0
    0,1,0,0,1,  # row 1
    0,1,0,1,1,  # row 2
    0,1,0,0,1,  # row 3
    0,1,0,1,1,  # row 4
]

def show_13(r, g, b, brightness=20):
    for i in range(NUM_LEDS):
        if PATTERN_13[i]:
            np[i] = (r * brightness // 255,
                     g * brightness // 255,
                     b * brightness // 255)
        else:
            np[i] = (0, 0, 0)
    np.show()

Passenger Counter

Every time the mat is pressed and released, the count goes up. The grid flashes the new number:

passenger_count = 0
was_pressed     = False
display_until   = 0

while True:
    pressed = is_pressed()

    # New press — count goes up
    if pressed and not was_pressed:
        passenger_count += 1
        show_13(255, 140, 66)  # orange-sodium
        display_until = time.monotonic() + 30

    # Display timeout
    if time.monotonic() > display_until:
        np.fill((0, 0, 0))
        np.show()

    was_pressed = pressed
    time.sleep(0.05)

AP Setup Page

When you hold the button, the device starts a web server:

import wifi
import socketpool
from adafruit_httpserver import Server, Request, Response

# Start AP mode
wifi.radio.start_ap(ssid="Tick", password="11111111")

pool = socketpool.SocketPool(wifi.radio)
server = Server(pool, "/static")

@server.route("/")
def index(request: Request):
    return Response(request, body=SETUP_HTML,
                    content_type="text/html")

@server.route("/save", methods=["POST"])
def save(request: Request):
    save_settings(request.form_data)
    return Response(request, body="Saved. Rebooting...")

server.serve_forever(str(wifi.radio.ipv4_address_ap))

Two things to hide: the mat and the device.

• The mat goes under a cushion, doormat, rug, or chair seat. Flat and thin — no one feels it through fabric.
• The ATOM Matrix hides nearby. Behind a table leg, under a shelf, inside a drawer with a gap. LED grid faces out so the glow is visible.
• Two wires run from the mat to GPIO 32 and GND on the ATOM Matrix. Route them along baseboards or under the rug.
• USB cable runs to a hidden power source — battery pack behind furniture, or a long cable to a hidden outlet.

No soldering on the ATOM Matrix itself. The pressure mat connects with two jumper wires and a 10K resistor. The device is 24mm square — it fits behind almost anything.

The device runs CircuitPython. When you plug it into a computer, it shows up as a USB drive called CIRCUITPY. The Tick code is a set of .py files on that drive. To update:

github.com/i4seer/tick-route-13

CIRCUITPY/
  code.py          ← main program
  tick_led.py      ← LED patterns + "13" display
  tick_web.py      ← AP setup page
  tick_trigger.py  ← pressure mat input + counter
  settings.toml    ← saved settings

Updates are optional. The device works out of the box. But if i4Seer releases new patterns, bug fixes, or features — this is how you get them. No special tools. Just copy files.