Mesh Beacon — Neighborhood LoRa Mesh with Solar Trickle & LTE SMS/Email Gateway
Operational, repeatable build: ESP32 + LoRa (US-915), solar-trickled nodes, a status board with a check-in button, and an LTE bridge that forwards critical messages to SMS/email when the internet resurfaces.
What you’re building
- Nodes (x3+) — ESP32+LoRa radios flashed with Meshtastic, 915 MHz antennas, solar-charged 18650s.
- Repeater — same hardware, elevated placement, router role enabled.
- Gateway — Meshtastic USB radio + mini PC/Raspberry Pi + LTE router; Python bridge to SMS/Email.
- Status Board — small display shows last messages; big pushbutton sends “I’m OK / Need help”.
Standards based, legal-use aware (FCC Part 15). Region set to US915 with proper power/channel presets.
Bill of Materials (core)
| LoRa Nodes | LILYGO T-Beam (ESP32 + SX1262/127x, 915 MHz) or Heltec WiFi LoRa 32 V2 |
|---|---|
| Antennas | 915 MHz whip (keep matched for US-915) |
| Solar (node) | 6 V 5–10 W panel → Adafruit BQ24074 Solar Li-ion charger → 18650 → 5 V boost |
| Gateway LTE | GL.iNet router (USB LTE or built-in) + SIM; or USB LTE modem to mini PC |
| Status Board | Raspberry Pi + 7″ HDMI or any small monitor; big momentary pushbutton |
Choose US-915 hardware and set the Meshtastic region to US during initial config.
Regulatory sanity & radio plan (US-915)
- Unlicensed band: 902–928 MHz under FCC Part 15; devices must not cause harmful interference and must accept interference. Use certified modules/boards and follow antenna/power limits in the firmware presets.
- Meshtastic Region: set to US (band 902–928 MHz). Use LongFast default unless you need LongSlow for extreme range. Avoid custom overrides until your basics work.
References: FCC Part 15; LoRaWAN US915 regional parameters (channelization & band); Meshtastic radio settings.
Node Power (solar trickle)
| Panel | 6 V 5–10 W mono panel |
|---|---|
| Charger | Adafruit BQ24074 Solar Li-ion (smart load-sharing) |
| Battery | 18650 Li-ion 3000–3500 mAh (protected) |
| Boost | Pololu U3V12F5 5 V step-up to power the ESP32 board |
| Fuse | Inline 2 A on battery + |
Solar 6V → BQ24074 VIN
BQ24074 BATT → 18650
BQ24074 LOAD (~3.7–4.4V) → 5V Boost → ESP32 5V
Ground common. Keep leads short. Add weather hood.
Gateway Power (bigger)
| Battery | 12 V LiFePO₄ 10–20 Ah |
|---|---|
| Solar | 100 W panel → Victron SmartSolar 75/15 |
| Loads | Meshtastic USB radio + Pi/mini-PC + LTE router |
| Fuse | Blade/MIDI fuses near battery + |
Panel → MPPT → 12V LiFePO₄ → 12V bus
12V → Pi (buck 12→5V) ; 12V → LTE router; Pi USB → Meshtastic radio.
Wiring Maps (ASCII)
[NODE SOLAR]
6V Panel ──► BQ24074 VIN
18650 ──► BQ24074 BATT
BQ24074 LOAD ──► 5V Boost ──► ESP32/T-Beam 5V
GND all common
(Inline 2A fuse on battery +; weatherproof box; strain relief)
[REPEATER]
Same as node; mount high (roof/mast). Meshtastic Device Role: Router/Repeater. External 915 MHz antenna.
[GATEWAY]
12V LiFePO₄ ─► Fuse ─► DC bus
Bus ─► Victron MPPT (from panel)
Bus ─► LTE router (12V)
Bus ─► Pi / mini-PC (buck 12→5V @3A)
Pi USB ─► Meshtastic radio (Heltec/T-Beam)
Pi runs Python bridge to SMS/Email.
Step-by-Step — Flash & Configure Meshtastic
- Flash firmware: Connect board via USB, open flasher.meshtastic.org in Chrome/Edge, select device, flash latest stable. Never power the radio without the antenna attached.
- Initial config: Using the app or web client/CLI, set Region = US, confirm 915 MHz band. Keep LongFast preset initially.
- Channels: Create a private primary channel (your neighborhood). Share via QR with neighbors. Optionally add a public secondary for discovery.
- Roles: On the high node, set Device Role = Router or Repeater; enable Store & Forward on fixed nodes if you want delayed delivery.
- Power tuning: Start at default TX power; only raise if needed. Follow local limits.
Docs: Web flasher + initial config + channels + radio presets are all in Meshtastic’s official docs.
“I’m OK” Check-In Button (no phone needed)
- Wire a normally-open pushbutton between GND and an unused GPIO (e.g., GPIO 26 on T-Beam).
- In Meshtastic, enable the Canned Message module:
- Input Source: scanAndSelect
- Input Broker Pin Press: your GPIO
- Preset list: “OK”, “Need help: water”, “Need help: medical”
- Press: cycles the presets; long-press: sends.
Module supports buttons/encoders; see docs for exact GPIOs per board.
Status Board (Pi + USB radio)
- Plug your Meshtastic node into the Pi via USB.
- Install Python libs: pip install meshtastic twilio sendgrid.
- Run the bridge script below to print the last 50 messages on screen and forward alerts to SMS/Email when LTE is up.
US SMS: comply with Twilio 10DLC rules; verify numbers/senders.
Gateway Bridge — Python (SMS/Email on LTE)
Create /opt/meshbridge/bridge.py, set env vars, then make a systemd service (unit file included below).
#!/usr/bin/env python3
import os, time, json, socket
import meshtastic
import meshtastic.serial_interface
from twilio.rest import Client
from sendgrid import SendGridAPIClient
from sendgrid.helpers.mail import Mail
TWILIO_SID = os.getenv(“TWILIO_ACCOUNT_SID”,””)
TWILIO_TOKEN = os.getenv(“TWILIO_AUTH_TOKEN”,””)
TWILIO_FROM = os.getenv(“TWILIO_NUMBER”,””)
SMS_NOTIFY = [n.strip() for n in os.getenv(“SMS_NOTIFY”,”+15551234567″).split(“,”)]
SENDGRID_KEY = os.getenv(“SENDGRID_API_KEY”,””)
EMAIL_FROM = os.getenv(“EMAIL_FROM”,”mesh@gamerzcrave.local”)
EMAIL_NOTIFY = [e.strip() for e in os.getenv(“EMAIL_NOTIFY”,”alerts@example.com”).split(“,”)]
KEYWORDS = os.getenv(“ALERT_WORDS”,”ALERT,HELP,911,SOS,MEDICAL,WATER”).split(“,”)
def has_inet():
try:
socket.create_connection((“1.1.1.1”, 53), timeout=2).close()
return True
except Exception:
return False
def send_sms(body):
if not (TWILIO_SID and TWILIO_TOKEN and TWILIO_FROM): return
try:
cli = Client(TWILIO_SID, TWILIO_TOKEN)
for n in SMS_NOTIFY:
cli.messages.create(from_=TWILIO_FROM, to=n, body=body)
except Exception as e:
print(“SMS error:”, e)
def send_email(subject, body):
if not SENDGRID_KEY: return
try:
sg = SendGridAPIClient(SENDGRID_KEY)
for dst in EMAIL_NOTIFY:
mail = Mail(from_email=EMAIL_FROM, to_emails=dst, subject=subject, plain_text_content=body)
sg.send(mail)
except Exception as e:
print(“Email error:”, e)
def on_text(packet, interface):
rx = packet.get(“decoded”,{}).get(“text”,””)
fr = packet.get(“fromId”,””)
tm = packet.get(“rxTime”,0)
msg = f”[{time.strftime(‘%Y-%m-%d %H:%M:%S’, time.localtime(tm))}] {fr}: {rx}”
print(msg, flush=True)
# alert routing
if any(k.strip().lower() in rx.lower() for k in KEYWORDS):
if has_inet():
send_sms(f”Mesh Alert: {rx} ({fr})”)
send_email(“Mesh Alert”, msg)
if __name__ == “__main__”:
iface = meshtastic.serial_interface.SerialInterface() # auto-detect /dev/ttyUSB*
iface.start()
pub = iface.pub
sub = iface.sub
# subscribe to text messages
sub.onMessage(on_text, “meshtastic.receive.text”)
print(“MeshBridge started.”)
try:
while True: time.sleep(1)
except KeyboardInterrupt:
pass
systemd unit (auto-start)
# /etc/systemd/system/meshbridge.service
[Unit]
Description=Meshtastic SMS/Email Bridge
After=network-online.target
[Service]
Environment=TWILIO_ACCOUNT_SID=ACxxxxxxxxxxxxxxxx
Environment=TWILIO_AUTH_TOKEN=xxxxxxxxxxxxxxxx
Environment=TWILIO_NUMBER=+15551234567
Environment=SMS_NOTIFY=+15559876543,+15557654321
Environment=SENDGRID_API_KEY=SG.xxxxxxxxxxxxx
Environment=EMAIL_FROM=mesh@gamerzcrave.local
Environment=EMAIL_NOTIFY=ops@example.com
Environment=ALERT_WORDS=ALERT,HELP,911,SOS,MEDICAL,WATER
ExecStart=/usr/bin/python3 /opt/meshbridge/bridge.py
Restart=always
User=pi
WorkingDirectory=/opt/meshbridge
[Install]
WantedBy=multi-user.target
Node Setup — Step-by-Step
- Assemble power: panel→BQ24074→18650→5 V boost→ESP32 5 V. Verify 5.0 V, polarity, and fusing.
- Flash Meshtastic via Web Flasher; pair the phone or use CLI; set Region=US.
- Create your private channel; share QR; keep LongFast.
- Enable canned messages on the node with the button wiring. Test sends.
- Weatherproof box, strain-relief, desiccant. Mount with the antenna vertical.
Repeater/Gateway — Step-by-Step
- Mount repeater high; set Device Role = Router/Repeater. Optional: enable Store & Forward.
- Gateway: wire 12 V system + MPPT + LTE router + Pi. Boot.
- Attach USB Meshtastic radio; run pip install meshtastic twilio sendgrid.
- Drop the Python script, enable the systemd unit, reboot. Send a test “ALERT Water at 5th & Pine”.
- Verify SMS/Email receipt. If no LTE, message stays on the mesh only; retries when back online.
Operational Checks
- Range walk: Send canned message every 100 m; log hops on status board.
- Power audit: Sunny/overcast overnight; confirm nodes don’t brown-out.
- Failover drill: Kill LTE; confirm mesh still passes messages; restore LTE; confirm SMS bursts arrive.
- Noise hygiene: Don’t spam the mesh; canned messages keep airtime light. Use Router role on fixed nodes only.
Quick-Start Card (print)
- Turn on nodes; antenna vertical; battery above 25%.
- Check the status board for last traffic.
- Press the big button to send “OK”. Long-press cycles messages (“Need water/medical”).
- If LTE is up, alerts mirror to SMS/email; if not, they still traverse the mesh.
- Solar: face south (N. hemisphere), tilt ~latitude; secure cables.
Bill of Materials — Links & Notes
Radios
- LILYGO TTGO T-Beam (choose 915 MHz option). Product • Meshtastic page
- Heltec WiFi LoRa 32 V2 (ESP32 + SX127x/SX1262). Overview • Docs
- Semtech SX1276 family (LoRa transceiver). Semtech • Datasheet
Power (node)
Mesh/Gateway Software
- Meshtastic Web Flasher & Initial Config. Flasher • Initial config
- Radio presets, channels & device roles. Radio settings • Channels • Roles
- Canned Messages & Store-and-Forward. Canned msg • S&F
- Python library/CLI. API • CLI
LTE & Email/SMS
- GL.iNet cellular setup (USB modem & built-in). Docs v4
- Twilio Programmable SMS Quickstart. Docs
- SendGrid Email API Quickstart (Python). Docs
Solar (gateway)
Legal & Safety
- Operate under FCC Part 15; do not exceed allowed power; your device must accept interference.
- Always attach the antenna before powering the radio.
- Use protected 18650 cells, correct polarity, and fuses near sources.
- Respect channel plans and duty-cycle etiquette; avoid spamming the mesh.