Teensy 4.1 Ethernet ingest

Push DS18B20 readings from a PJRC Teensy 4.1 with QNEthernet and the Ethernet kit. Fast i.MX RT1062 garage probe using the same LAN HTTPS relay as the Uno shield.

Close-up of white Cat-5e Ethernet cables with RJ45 connectors
Probe JSON usually leaves the LAN over Ethernet or a nearby relay, not the public internet directly. Photo: DiscDepotDundee.co.uk. CC BY-SA 4.0

PJRC Teensy 4.1 (NXP i.MX RT1062) with the official Ethernet kit is a fast Cortex-M7 garage probe in Teensyduino + QNEthernet—not STM32 Zephyr tooling, not WCH MounRiver. DS18B20 on pin 4 → temp1. HTTP to the LAN TLS relay, same CA story as Uno Ethernet.

Parts

Parts for a Teensy 4.1 freeze probe
Part Why Buy
Teensy 4.1 600 MHz M7, USB flash, onboard Ethernet MAC (needs magnetics kit). PJRC Teensy 4.1 · Amazon
Ethernet kit / MagJack Magnetics + RJ45 wired per PJRC Teensy 4.1 Ethernet docs. PJRC Ethernet kit
Waterproof DS18B20 Data on pin 4, 4.7k to 3.3V. Adafruit DS18B20 · Amazon
4.7kΩ resistor 1-Wire pull-up to 3.3V. Amazon 4.7k

Wiring

  • DS18B20 VDD → 3.3V
  • DS18B20 GND → GND
  • DS18B20 data → pin 4, 4.7k to 3.3V
  • Ethernet kit → LAN. USB for Teensyduino flash and Serial 115200

Build and flash

  1. Open Dashboard → Devices and download Teensy 4.1 .ino (ingest path filled in).
  2. On a LAN host: 
    python3 sketches/relay/push_https_forward.py --listen 0.0.0.0:8080 \
  --upstream https://thermaltrace.dev
  3. Install Teensyduino. Add QNEthernet, OneWire, DallasTemperature. Set INGEST_HOST, flash.
  4. Serial 115200: link ok, dhcp ok, then POST 200. Sensor key temp1 imports on first POST.

Repo listing: sketches/teensy/teensy41_ds18b20_ingest/

Related

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FAQ

Can a Teensy 4.1 post to ThermalTrace?
Yes. Teensyduino + QNEthernet on Teensy 4.1 with the Ethernet kit: DS18B20 on pin 4, HTTP to the LAN TLS relay. Guide: thermaltrace.dev/about/teensy41-ingest.

Why not HTTPS straight from the Teensy?
You can add TLS libraries, but Cloudflare CAs can change. The LAN relay matches Uno / STM32 / CH32V and avoids baking CAs into the MCU.

Do I need the PJRC Ethernet kit?
Yes for this sample. The Teensy 4.1 has the MAC on-chip; the kit (or equivalent MagJack wiring) provides magnetics and RJ45.