Signaloid C0-microSD is an iCE40UP5K FPGA SoM in the microSD card form factor (Crowdfunding)

Cambridge-based hardware and cloud computing company, Signaloid has begun crowdfunding for the C0-microSD – a tiny, programmable iCE40UP5K FPGA system-on-module (SoM) in a microSD card form factor. It comes preloaded with a RISC-V softcore and users can also load custom FPGA designs onto the board.

Part of the Signaloid C0-microSD’s unique appeal is its SD card form factor, which allows it to fit in unused full SD or microSD slots. This allows the implementation of FPGA-based hardware acceleration in systems without traditional expansion interfaces like PCIe M.2 slots. It can also be interfaced with as a standard SD block device and used to bring hardware-accelerated data processing to existing industrial automation, manufacturing, and robotics systems.

The iCE40UP5K FPGA SoM has two main use cases: a hot-pluggable FPGA module or a hot-pluggable RISC-V co-processor module. The SD interface allows you to load custom FPGA bitstreams and applications onto the module from a host computer.

We have covered several tiny FPGA SoMs – MYIR Tech’s MYC-J7A100T, the NiCE5340 SoM, iWAve’s iW-RainboW-G58M – but the C0-microSD is the first we’ve seen in a microSD card form factor.

Signaloid C0-microSD specifications:

• FPGA – Lattice UltraPlus iCE40UP5K FPGA with
  • 5.3K LUTs
  • 1Mbit SPRAM, 120Kbit DPRAM
  • 48MHz internal oscillator
  • Preloaded with Signaloid C0 RISC-V softcore
• Memory – 128Mb (16MB) non-volatile storage (Renesas AT25QL128A SPI Flash)
• USB – Via USB-to-MicroSD adapter
• Connectivity – SD interface, SD-over-SPI
• Expansion
  • 6x programmable I/O pins on SD interface
  • 5x programmable pins on test pads
• Misc – Two on-board LEDs (one red and one green) for status indication
• Form Factor – microSD card

Signaloid provides a Raspberry Pi CM4-compatible carrier board, Signaloid SD-Dev, which exposes several peripherals for testing and working with the module in a standalone configuration.

Signaloid SD-Dev Carrier Board specifications:

• Supported SoM – Raspberry Pi CM4 or CM4 Lite
• Video Output – 1x Micro HDMI
• USB
  • 2x USB Type-C downstream ports
  • 1x USB Type-C upstream port
• Expansion
  • JST connectors for SPI and I²C peripherals
  • 1x full-size SD slot and 1x microSD slot (open-top) for Signaloid C0-microSD or regular SD cards
  • 1x microSD slot (OS storage for Raspberry Pi CM4)
• Power – 1x USB Type-C (power-only)
• Peripheral and standalone modes
• Dimensions – 57 x 57 mm

The C0-microSD is compatible with open-source toolchains for the iCE40 FPGA, such as Icestorm, Yosys, NextPnR, and Icestudio, as well as AmaranthHDL and the LiteX framework. The online documentation website offers detailed guides for using the device. Hardware schematics, sample code, and software utilities for the module are available on GitHub.

Signaloid lists some possible applications for the SoM, including performing deterministic arithmetic on probability distributions from legacy edge-of-the-network devices, bringing low-power FPGA hardware acceleration to local embedded systems (e.g. factory floor PLCs), and augmenting hobbyist or maker projects in Arduino-compatible hardware. The iCE40UP5K FPGA SoM can also be used as a small, low-power microcontroller using the LiteX framework for embedded applications.

The Crowd Supply campaign for the Signaloid C0-microSD FPGA SoM has already reached its funding goal of $2500 after a couple of days. The module alone is priced at $45 but you can buy the module and the Raspberry Pi CM4 carrier board for $180. Shipping is free within the US but costs $12 to the rest of the world. Orders are expected to shp by May 9, 2025.

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.

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