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LoRa Expansion Card

The LoRa Expansion Card is a community-developed expansion card that adds LoRa (Long Range) wireless communication to Framework laptops1. Multiple community members have contributed designs, with the most advanced being by S115 (Sil Schouten), which successfully ran Meshtastic firmware and established LoRa reception in May 20251.

Background​

LoRa is a low-power wide-area network (LPWAN) modulation technique designed for long-range communication (up to several kilometers) at low data rates. It is widely used in IoT, sensor networks, and community mesh networking projects like Meshtastic1. A LoRa expansion card enables Framework laptops to participate in LoRa mesh networks for off-grid communication without WiFi or cellular connectivity1.

Framework VP nrp (Kieran Levin) actively contributed technical guidance to the project, suggesting integrated matching/balun components and alternative modules1.

S115's Design (SX1262 / Murata Type 2GT)​

V1: SX1262 + MCP2210 (2024)​

The initial design used a discrete Semtech SX1262 transceiver with an MCP2210 USB-to-SPI bridge and an RF filter circuit based on a Pine64 reference design12. PCBs were ordered in September 2024 and assembled in October 20241.

Community member Doridian received a V1 prototype and began porting Meshtastic firmware, discovering that the CS (chip select) pin was not connected to the MCP2210's GPIO — requiring a bodge wire fix1. This led to the V2 redesign.

V2: Murata Type 2GT + RP2040 (2025)​

The V2 redesign made two major changes1:

  • Replaced MCP2210 with RP2040 — Cheaper, more flexible, and capable of running Meshtastic firmware directly
  • Switched to Murata Type 2GT module — A pre-certified integrated LoRa module (LBAA0XV2GT-001) based on the SX1262, simplifying RF design1
  • Dropped retrofit outline — Uses a standard expansion card form factor, freeing space for a chip antenna variant

The V2 PCB was completed in January 2025, with the first board assembled by the end of that month1. After fixing a flash chip issue, the RP2040 successfully enumerated as a serial device. In May 2025, Meshtastic firmware (v2.6.8) was confirmed running with the RP2040_LORA hardware model1. LoRa reception at 868 MHz was confirmed working, though transmitting was still being debugged1.

Technical Specifications​

SpecificationV1V2
TransceiverSemtech SX1262 (discrete)Murata Type 2GT (LBAA0XV2GT-001)
USB InterfaceMCP2210 (USB-to-SPI)RP2040
RF FilterCustom (Pine64 reference)Integrated in Murata module
Frequency868/915 MHz868/915 MHz
Antenna ConnectorSMA (protruding 0.7 mm)Chip antenna + external option
Form FactorRetrofit (modified)Standard expansion card
SoftwareMeshtastic (partial)Meshtastic v2.6.8 (receiving)
SourceGitLab2Not yet published
Estimated BOM~$20–30 USD1TBD

Other LoRa Expansion Card Projects​

Drew_Nucci's Heltec HT-CT62 Design​

Community member Drew_Nucci began a parallel design using the Heltec HT-CT62 LoRa module (~$7 USD), planning dual screw-on antenna connectors recessed into the card alongside an internal fractal PCB antenna salvaged from a laptop1. The design uses IPEX connectors on the module to avoid the challenge of fitting SMA connectors within the expansion card height constraint1. The project was paused in mid-20241.

Madhav_Kapa's 433 MHz Design​

Community member Madhav_Kapa designed a 433 MHz LoRa card using an Ebyte E22-400MM22S module and an STM32F0 MCU, with files published on GitHub1. PCBs were fabricated but not yet assembled as of February 20251.

Antenna Design Challenges​

A recurring challenge across all LoRa expansion card designs is the antenna connector1:

  • SMA connectors are too tall to fit within the standard expansion card height when surface-mounted
  • S115 explored floating the SMA connector centered on the PCB rather than SMD-mounting it
  • nrp suggested MMCX mid-mount connectors as a compact alternative
  • Drew_Nucci proposed recessed SMC connectors with SMA adapters
  • The V2 design addresses this with an integrated chip antenna option

Footnotes​

  1. LoRa Expansion Card — Framework Community (S115, March 2024 – August 2025) ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15 ↩16 ↩17 ↩18 ↩19 ↩20

  2. Framework ExpansionCard LoRa — SillieWous (GitLab) ↩ ↩2