LimeNET Micro 2.0 Developer Edition board leverages Raspberry Pi CM4 and LimeSDR XTRX SDR module (Crowdfunding)

The LimeNET Micro 2.0 Developer Edition board is a modular software-defined radio (SDR) platform from Lime Microsystems that is based on the Raspberry Pi Compute Module 4 and the company’s own SDR board, the LimeSDR XTRX.

It builds upon previous versions from Lime Microsystems, such as the LimeSDR Mini and LimeSDR Mini 2.0. It features a MIMO (multiple-input, multiple-output) radio and runs the more powerful Compute Module 4, an upgrade from the Raspberry Pi CM3 in earlier versions.

The LimeSDR XTRX is an open-source, high-performance SDR in a compact, Mini PCIe form factor. It provides a platform for building logic-intensive digital and RF designs and can be used for MIMO antenna configurations from 2Tx2R to 32Tx32R.

The platform is built around a planar system board, the LimePSB RPCM, which integrates the CM4, the XTRX, and other components and interfaces to make a complete baseband + RF solution for diverse wireless applications. These potential applications include satellite ground stations, amateur digital TV and audio broadcasts, wildlife tracking, drone command and control, radio astronomy, and bit pattern generation. There is a detailed description of the RPCM board on a separate webpage.

LimeNET Micro 2.0 Developer Edition specifications:

SoM – Raspberry Pi CM4, with Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz
Software-Defined Radio – LimeSDR XTRX MIMO radio, with AMD Artix 7 XC7A50T-2CPG236I FPGA and Lime Microsystems LMS7002M RF transceiver
Storage – microSD card slot
Connectors
- Raspberry Pi CM4 connectors (dual row)
- Video and audio output
  - 2x HDMI 2.0 receptacle (up to 4Kp60 supported)
  - 5-pin front display connector (power, I2C, button)
  - 2x 15-pin FPC connectors for MIPI DSI display
  - 3.5 mm four-pin jack for analog audio and composite video
- Networking – Gigabit Ethernet with PoE
- USB – USB 2.0 Type-C (boot and power delivery), 2x USB 2.0 Type-A downstream ports, Front Panel USB 2.0 header (unpopulated)
- Expansion
  - mini PCIe x1 Gen 2 (5 Gbps)
  - nano-SIM socket
  - Raspberry Pi CM4 – 20-pin GPIO header (3.3 V), 14-pin SYS header, UART0 header (unpopulated)
- Misc – 2-pin and 4-pin fan connector (5 V default or 3.3 V or VCC_INT voltage)
RF front end
- Configuration: MIMO (2x TRX, 2x RX)
- LNAs, PAs, RF switches, power, and mode control (TDD and FDD)
- Coaxial RF (4x SMA female + 4x U.FL female) connectors for RF front end
- Coaxial pass-through U.FL to external SMA connector
Misc – Temperature sensor, shift registers, EEPROM, USB 2.0 hub (unpopulated) secure key storage, shift registers, RTC, ADC, 4x RG user LEDs, status LEDs (power, CM, Ethernet), front button and buzzer
Clock system – 30.72 MHz (default) onboard VCOCXO and 30.72/38.4/40.00 MHz (optional) VCTCXO oscillators
Power
- Barrel jack connector (9-14 V, 2-3 A)
- USB Power Delivery (12 V, 1.5 A or 2.5 A)
- Power over Ethernet (12 V, 2 A)
Dimensions – 170 x 110 mm

The LimeSDR board supports the free, 64-bit version of Xilinx Vivado v2022.1, and a gateware project for the FPGA can be found hosted on GitHub. It is also fully supported by the Lime Suite software stack, as well as Fairwaves’ legacy XTRX gateware and driver to retain compatibility and aid the transition from earlier devices.

The LimeNET Micro 2.0 Developer Edition board has been successfully funded on Crowd Supply with 36 days left to go, due to the $1 symbolic funding goal. You can get the carrier board (Lime Planar System Board) alone for $799, while the LimeNET Micro 2.0 DE (i.e. the complete package with the CM4, an enclosure, and a cooling fan pre-installed) is priced at $1,699.

For users that want to go all in and build a complete private 5G network, there is an $11,900 5G Deluxe Kit that features the LimeNET Micro 2.0 DE plus SMA antennas, a compatible power supply, 5G stack, and Amarisoft core, two 5G smartphones, and ten SIM cards. There are other product offerings listed on the Crowd Supply page. All orders will be fulfilled by Mouser Electronics and are expected to ship by November 30, 2024.

Tomisin Olujinmi

Tomisin is a writer specializing in hardware product reviews, comparisons, and explainers. He is very passionate about small form factor and single-board computers.