Say “Hello” to the OrangeCrab

After a complicated half decade where we saw a Cambrian explosion in the number of form factors for micro-controllers we’re now seeing a…

Alasdair Allan
a year ago

After a complicated half decade where we saw a Cambrian explosion in the number of form factors for micro-controllers boards, we’re now seeing a collapse. With Arduino in the process of abandoning their “classic” form factor that has for some years been the default, in favour of something more modern, the community seems to be adopting Adafruit’s own Feather as the next standard.

In fact, perhaps we should just call it now? The Feather form factor has won.

But as well as a new de facto standard form factor, we’re also seeing what feels like a sea-change in the languages and methodology to program the boards we’re using. Field-programmable gate arrays (FPGAs) have come of age. Once viewed as exotic and scary there are now a number of FPGA boards targeting the maker market, and among them is the new OrangeCrab board.

Designed and prototyped by Greg Davill, the Feather-compatible OrangeCrab is built around a Lattice Semi ECP5 FPGA, and can have up to 8Gbit of DDR3 memory on board. With 118 available I/O pins, the board initially seems to be missing a lot of I/O. But the DDR3 memory takes 50+ of those pins, which means that although “…every 3.3v IO pin available on this package has been exposed via the standard 0.1" header or SMD test points” there are a lot fewer than you might initially expect, albeit more than enough to make the board Feather-compatible.

The board also supports a micro USB connector, with full-speed direct USB connection to FPGA, 128Mbit of QSPI Flash memory, a micro SD Card socket, and a LiPo battery connector.

Since it’s based on the ECP5 FPGA, the toolchain for the board is fully open source, and the board is capable of running a soft RISC-V core. However interestingly, since “…the USB lines re hooked directly to the ECP5. So it should be possible to port [the CircuitPython] implementation done on Fomu over to this board.

If you want to know more about the board Davill has an amazingly detailed Tweet thread showing the evolution of the board from conception through to prototyping, with some excellent macro photography of the board. More on the board, including schematics and Gerbers, can be found on the project’s GitHub repo.

But, unfortunately, the board isn’t available for sale. At least not yet?

Alasdair Allan
Scientist, author, hacker, maker, and journalist. Building, breaking, and writing. For hire. You can reach me at 📫
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