Now on GroupGets: RISC-V LoFive R1

GroupGets
5 months ago

The RISC-V LoFive breakout just received a fresh update and here to tell you about it in his own words is Michael Welling of Qwerty Embedded Design. Welling is no stranger to using GroupGets to crowdfund production funds for his works. He graciously brought us the PocketBone, the original LoFive, and BaconBits. While on his flight home from the first KiCon in Chicago, our co-founder Ron Justin shot him over these questions about the LoFive R1, which is now +80% funded on GroupGets. Enjoy!

When and how did RISC-V get on your radar? It wasn’t on ours at all until you showed us your first LoFive board.

I think that RISC-V first garnished more of my attention in 2016 after meeting a few members of the FOSSi team at the Google Summer of Code mentor summit. They mentioned many software efforts related to free silicon including RISC-V implementations. Around the same time, the HiFive1 first released to crowdfunding and 2017 would be the year the RISC-V really took off.

Why might someone want to use a SiFive FE310 MCU? Is it more of a curiosity at this point for open source silicon or is it ready for production designs?

I think the FE310 was intended more pulling in contributions from the community while showcasing the core IP. I don’t think that it was ever intended for mass production. That said, the FE310 is very capable through its limitations making it very fun to work with. You would expect users to be in it for the educational and software ecosystem development value.

What is the development environment like for SiFive parts compared to ST or ATmega?

The development environment is multifaceted and provides support from command line to Eclipse integration. At its core is the Freedom-E SDK which offers board support and basic examples. This SDK can be used directly from the command line and can be used to build and program basic examples.

The SDK can also be combined with an IDE to make it more palatable for some developers. Freedom Studio, SiFive’s Eclipse based IDE, leverages the SDK and provides cross platform support.

More recently, the SDK was further broken down into the Freedom Metal core which provides a bare metal development suite.

There is partially baked Arduino support, RTOS ports, and very preliminary MicroPython implementations as well. Interestingly enough, MicroPython was ported to LoFive even before the HiFive1.

We saw on Twitter that you will design some accessories for LoFive R1 as stretch goals. What do you have in mind?

The goal is to offer a base board with features for programming and basic IO right out of the box.

I stated that I would design this base board accessory if 100% is reached. To further incentivize orders, for every 50% over the stated campaign goal a feature would be added to the base board.

The new features will be decided upon based on community feedback and perhaps a poll when the stretch goals are met. Kind of like one of those choose your own adventure books

Tell us about some of the updates for the R1 board.

The R1 was developed out of necessity as the FE310 silicon was revised. This revised silicon in turn provides a few new key features.

They added I2C support in this revision allowing users to more easily integrate I2C devices from analog converters to sensors to IO expansion.

An additional UART was added as part of the revision, too. This UART could be used to communicate to co-processors and is specifically useful for adding various types of wireless connectivity.

The always-on domain was moved to 3.3V to simplify the power tree and allow for the 1.8V regulator to be shut down to enable lower power consumption in sleep modes.

There were also updates related debugging circuitry based an updated RISC-V debugging specification 0.13.

Beyond the silicon updates, the LoFive added castellated edges to the PCB for more advanced prototyping. I can’t wait to see what users do with the new features.

We can’t either. Thanks for your time here and for your prolific works!

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