CaribouLite RPi HAT: Turn Your Raspberry Pi into a Dual-Channel SDR

CaribouLite, designed by CaribouLabs, is a fully open-source dual-channel Software-Defined Radio (SDR) HAT for the Raspberry Pi. It streams 4 MSPS I/Q samples (both TX and RX) over the RPi's Secondary Memory Interface (SMI), turning a Raspberry Pi SBC into a self-contained dual-channel radio with a tunable spectrum reaching up to 6 GHz.

Hardware Highlights

  • Dual-channel SDR: Channel 1 covers 30 MHz – 6 GHz; Channel 2 covers the sub-1-GHz band
  • Onboard ice40lp1k FPGA, tightly integrated with the open-source IceStorm toolchain for custom FPGA development
  • Internal TCXO clock source and low-noise amplifier (NF < 4 dB below 3 GHz)
  • TX power up to 14 dBm
  • 8-bit read/write PMOD expansion ports for direction finding, GPS synchronization, and more
  • Clearly labeled front-end sections and TX/RX indicators — great for teaching and debugging

Two Versions Available

Version Frequency Range Notes
Full Version Ch.1: 30 MHz – 6 GHz; Ch.2: sub-1-GHz Full dual-channel SDR
ISM Version 2.4 GHz & sub-1-GHz Cheaper; closely follows the Microchip AT86RF215 reference design for easier ETSI/FCC compliance

In practice, the wideband channel's lower bound was measured closer to ~1 MHz, but CaribouLabs sticks with the official chip specs.

Software Stack: Fully Open Source

CaribouLite is auto-recognized by Raspbian at boot (board variant detected via on-board configuration resistors), and the EEPROM ships with the device-tree overlay and drivers pre-programmed.

  • Full support for SoapySDR / GNU Radio / Jupyter Notebooks
  • Ships with libcariboulite, device-tree overlays, and sample code
  • Each board is exposed as two SDR devices (sub-1-GHz + wideband) for backward compatibility with SDR++, GQRX, CubicSDR, GNU Radio, and more
  • FPGA firmware is programmed by libcariboulite via a CLI-friendly API at session start
  • The onboard AT86RF215 modem includes built-in IEEE 802.15.4 PHY cores, so ZigBee / Thread nodes can run without extra SDR programming

Crowdfunding Status

The campaign set out with a $112,000 goal and ultimately raised $316,279 — 282% funded — with 1,873 backers. Units start at $79 – $149; assembly is finished and production testing is underway.

  • Campaign page: https://www.crowdsupply.com/cariboulabs/cariboulite-rpi-hat
  • Software repo: https://github.com/cariboulabs/cariboulite/tree/main/software
  • libcariboulite & SoapySDR drivers: https://github.com/cariboulabs/cariboulite/tree/main/software/libcariboulite
  • Device-tree overlays: https://github.com/cariboulabs/cariboulite/tree/main/software/devicetrees

Who Is It For?

Positioned by CaribouLabs as an affordable, open-source SDR building block for makers, hackers, educators, and researchers — useful for analog FM / DAB+ receivers, ADS-B receivers, signal relays, and signal/protocol generators.