Raspberry Pis and Arduino Projects
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Xen Project officially ports its hypervisor to Raspberry Pi 4
The idea to do an official port bubbled up from the Xen community and then reached the desk of George Dunlap, chairman of the Xen Project’s Advisory Board. Dunlap mentioned the idea to an acquaintance who works at the Raspberry Pi Foundation, and was told that around 40 percent of Pis are sold to business users rather than hobbyists.
With more than 30 million Arm-based Pis sold as of December 2019, and sales running at a brisk 600,000-plus a month in April 2020, according to Pi guy Eben Upton, Dunlap saw an opportunity to continue Xen’s drive towards embedded and industrial applications.
Stefano Stabellini, who by day works at FPGA outfit Xilinx, and past Apache Foundation director Roman Shaposhnik took on the task of the port. The pair clocked that the RPi 4's system-on-chip used a regular GIC-400 interrupt controller, which Xen supports out of the box, and thought this was a sign this would, overall, be an easy enough job. That, the duo admitted, was dangerous optimism. Forget the IRQs, there was a whole world of physical and virtual memory addresses to navigate.
The pair were “utterly oblivious that we were about to embark on an adventure deep in the belly of the Xen memory allocator and Linux address translation layers,” we're told.
“The first hurdle was the availability of low memory addresses,” the pair wrote in an announcement heralding the Xen Pi port, seen by The Register ahead of its public release today. “RPi4 has devices that can only access the first 1GB of RAM. The amount of memory below 1GB in Dom0 was not enough. Julien Grall solved this problem with a simple one-line fix to increase the memory allocation below 1GB for Dom0 on RPi4. The patch is now present in Xen 4.14.”
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Xen Project Officially Ports Its Hypervisor To Raspberry Pi 4
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Xen on Raspberry Pi 4 adventures
Raspberry Pi (RPi) has been a key enabling device for the Arm community for years, given the low price and widespread adoption. According to the RPi Foundation, over 35 million have been sold, with 44% of these sold into industry. We have always been eager to get the Xen hypervisor running on it, but technical differences between RPi and other Arm platforms made it impractical for the longest time. Specifically, a non-standard interrupt controller without virtualization support.
Then the Raspberry Pi 4 came along, together with a regular GIC-400 interrupt controller that Xen supports out of the box. Finally, we could run Xen on an RPi device. Soon Roman Shaposhnik of Project EVE and a few other community members started asking about it on the xen-devel mailing list. “It should be easy,” we answered. “It might even work out of the box,” we wrote in our reply. We were utterly oblivious that we were about to embark on an adventure deep in the belly of the Xen memory allocator and Linux address translation layers.
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Raspberry Pi CM3+ based Iono Pi Max industrial controller comes with an impressive number of I/Os
As the Raspberry Pi Compute Module 4 is only expected for next year, companies are still launching products based on Raspberry Pi Compute Module 3+ (CM3+), and Sfera Labs has just introduced Iono Pi Max industrial computer powered by a Raspberry Pi CM3+ system-on-module.
Housed in a DIN rail enclosure, the Linux controller offers Fast Ethernet, three USB ports, isolated CAN and serial boards, some analog I/Os, a relay, as well as a real-time clock (RTC), integrated UPS, and more.
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FPGA Meets Breadboard with Mercury 2 Xilinx Artix-7 FPGA Development Board
All those boards are however based on entry-level FPGAs like Lattice Semi ICE40 or QuickLogic EOS S3, and if you’d like a more powerful FPGA board that fits into a breadboard, MicroNova Mercury 2 development board may meet your requirements with a Xilinx Artix-7 FPGA.
[...]
The baseboard comes with a 64-bit socket for the FPGA devboard, as well as a 4-digit seven-segment display, four push-buttons & eight toggle switches, a PS/2! port for keyboard or mouse, a VGA port, a Pmod-compatible connector, 3.5mm audio jacks, an analog temperature sensor, a light sensor, and a potentiometer for use with the analog-to-digital converter.
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How a Half-Dozen Raspberry Pis Help Keep This Maine Oyster Farm Afloat
Running Tide built a 60-by-24-foot oyster processing boat, now docked in a finger of Casco Bay in the town of Harpswell, with two oyster reefs floating at each end of the vessel. Inside the processing boat are a half-dozen Raspberry Pis that feed data to the cloud on water conditions, including temperature and acidity. The boat is essentially a huge catamaran that allows the 11-by-36-foot oyster reefs to float into it.
Running Tide’s Margaux Filippi, who has a PhD. from MIT and the Woods Hole Oceanographic Institute, said the company is working on underwater video cameras to monitor the oysters’ growth. The 29-year-old data scientist has built machine learning algorithms for ocean research and spent six years at MIT’s mechanical engineering department, where she mastered the process of rapid prototyping. She clearly enjoys Running Tide’s hacker culture.
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Watch your houseplant’s growth really take off in this Saturn V planter
A switch on the front lights up the printed flame assemblies emanating from the engines, using a trio of SMD LEDs on each exhaust. These LEDs are controlled by an Arduino Nano nestled inside the wooden base to produce random lighting effects when an activation button is pressed.
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This interactive screen slides smoothly from side to side
When you need to grab someone’s attention at an event, an interactive screen is a good idea. MakerMan, however, went several steps beyond this, creating an installation with a bank of static screens that depict the Moscow skyline. In front of this, a single touch-enabled display moves back and forth automatically to present information on various points of interest.
Sliding action is handled by a large stepper motor, which pulls the screen along on a carriage assembly. The motor, in turn, is controlled via an Arduino Uno and a stepper driver. All of these electronics are hidden behind a nicely painted wooden facade, letting the technology driving it fade elegantly into the background.
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