Oak Development Pairs a Lattice iCE40 FPGA with a Raspberry Pi RP2040 for the RPGA Feather

Built in the familiar Feather form factor, this board combines microcontroller and FPGA capabilities in one.

Gareth Halfacree
1 month agoFPGAs / HW101

Oak Development Technologies has launched a new Feather-format development board for the FPGA enthusiast — and this one pairs a Lattice Semiconductor iCE40 FPGA with the popular Raspberry Pi RP2040 dual-core microcontroller: the RPGA Feather.

"What better way to enjoy a Raspberry Pi RP2040 than to pair it with an iCE40 FPGA," Oak Development Technologies' Seth Kerr asks, rhetorically, in reference to his latest creation. "[This] iCE40 FPGA provide a small but capable accessory to your favorite project without the hassle of figuring out the wiring and which pins to hook up!"

This is far from Oak's first Feather-format FPGA design. Back in February 2023 the company unveiled the IcyBlue Feather, which played host to a Lattice Semi iCE5LP4K; in April this year it was upgraded to a V2 design that added USB Type-C connectivity. The Lattice FeatherWing, meanwhile, was designed to add an iCE5LP4K to existing Feather-format projects — while the new RPGA Feather goes back to being a standalone board once more.

On the FPGA side of the equation, the RPGA Feather uses the familiar Lattice iCE5LP4K, delivering 3,520 look-up tables (LUTs) and a total of 80kb of block ram (BRAM) plus dedicated hardware I2C and SPI blocks. On the microcontroller side, the familiar Raspberry Pi RP2040 delivers two Arm Cortex-M0+ cores running at 133MHz stock, 264kB of static RAM (SRAM), and clever programmable input/output (PIO) blocks capable of running state machines separately to the CPU cores.

The board includes a USB Type-C connector for programming and power, which can charge an optional lithium-polymer battery. There are eight direct pin connections from the FPGA to the microcontroller, Kerr notes, with a further jumper-selectable as either being connected or left as free input/output pins for the FPGA alone. There's an on-board RGB LED connected to the FPGA, and 2MB of QSPI flash for the RP2040.

The RPGA Feather is available to order from the Oak Development Technologies Tindie store at $46.95; hardware design files and software source code are available on the project's GitHub repository under the permissive MIT license.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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