Recore Hacks The Hidden Microcontroller For 3D Printing

June 14, 2021 by Chris Lott 24 Comments

No stranger to the world of 3D printers, [Elias Bakken] from the [Intelligent Agent] workshop has released a new controller board called Recore. The typical 3D printer has a dedicated controller which handles the real-time aspects of driving stepper motors. Many setups also have a second computer, often Linux-based, which is dedicated to supporting tasks like running an Octoprint server and interfacing to a digital camera to monitor print progress remotely. [Elias]’s design merges these together into one compact 12 x 12 x 4 cm package.

The Recore board is powered by an AllWinner A64 system on chip (SoC) which packs four ARM Cortex-A53 AArch64 cores running Debian Linux. The applications include Klipper, a project we wrote about when it was first introduced, and the OctoPrint print server. “But Linux is not a real-time operating system”, we hear you cry, “and controlling stepper motor drivers from an A64 SoC is just asking for trouble”. [Elias] could have addressed this problem by putting a secondary microcontroller on the board, but he found an even more elegant solution instead.

It turns out that there is already a secondary microcontroller hidden in plain sight, integrated into the A64 itself. See that small box labeled AR100 at the top of the block diagram? Meet the AR100, a controller originally intended to manage low-power operations of the A64. It is an OpenRISC 32-bit OR1k processor. But the AR100 is extremely underutilized, and [Elias] takes good advantage of this by repurposing it to those real-time tasks associated with a 3D printer controller. Watch the short video down below to learn how he solves a few of the nitty-gritty implementation details such as timers and communicating with the Linux processors. You might learn some tips from the other short videos in the series featuring some interesting debugging and problem solving sessions. There is a project GitHub repository and a Wiki full of good information and testing results.

[Elias] has a long history of building printer controllers. While his last one had to be abandoned because of manufacturing issues, he learned from that experience. Manufacturability was a top priority in the design of the Recore. We’re jealous of the well-appointed [Intelligent Agent] facility in Norway, but even more so of the nomadic lifestyle that [Elias] appears to enjoy — in his videos, he can be seen working from far-flung locales such as a tropical island resort and a laboratory floating in high Earth orbit. We’ve featured [Elias]’s projects in the past, including the Replicate 3D printer controller, a semi-automatic liquor cabinet, and the dog-operated treat dispenser.

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RISC-V: Why The ISA Battles Aren’t Over Yet

November 12, 2019 by Maya Posch 39 Comments

A computer processor uses a so-called Instruction Set Architecture to talk with the world outside of its own circuitry. This ISA consists of a number of instructions, which essentially define the functionality of that processor, which explains why so many ISAs still exist today. It’s hard to find that one ISA that works for as many distinct use cases as possible, after all.

A fairly new ISA is RISC-V, the first version of which was created back in 2010 at the University of California, Berkeley. Intended to be a fully open ISA, targeting both students (as a learning tool) and industrial users, it is claimed to incorporate a number of design choices that should make it more attractive for a number of applications.

In this article I’ll take a look behind the marketing to take stock of how exactly RISC-V differs from other open ISAs, including Power, SPARC and MIPS.

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A FPGA Based Bus Pirate Clone

March 10, 2014 by Eric Evenchick 19 Comments

A necessary tool for embedded development is a device that can talk common protocols such as UART, SPI, and I2C. The XC6BP is an open source device that can work with a variety of protocols.

As the name suggests, the XC6BP is a clone of the Bus Pirate, but based on a Xilinx Spartan-6 FPGA. The AltOR32 soft CPU is loaded on the FPGA. This is a fully functional processor based on the OpenRISC architecture. While the FPGA is more expensive than a microcontroller, it can be fully reprogrammed. It’s also possible to build hardware on the FPGA to perform a variety of tasks.

A simple USB stack runs on the soft CPU, creating a virtual COM port. Combined with the USB transceiver, this provides communication with a host PC. The device is even compatible with the Bus Pirate case and probe connector. While it won’t replace the Bus Pirate as a low-cost tool, it is neat to see someone using an open source core to build a useful, open hardware device.