Testing the Outernet Dreamcatcher SDR

What do you get when you cross an ARM-based Linux PC and an RTL-SDR? Sounds like the start of a joke, but the answer is Outernet’s Dreamcatcher. It is a single PCB with an RTL-SDR software defined radio, an L-band LNA, and an Allwinner A13 processor with 512MB of RAM and a 1 GHz clock speed. The rtl-sdr site recently posted a good review of the $99 board.

We’ll let you read the review for yourself, but the conclusion was that despite some bugs, the board was no more expensive than pulling the parts together separately. On the other hand, if you uses, for example, a Raspberry Pi 3, you might expect more support and more performance.

Despite the L-band hardware, there is a bypass antenna jack that allows you to receive other frequencies. There’s also two SD slots, one to boot from and another for storage. Several pieces of software had trouble running on the somewhat sluggish CPU, although some software that is optimized for the particular processor used fared better. You can read the details in the review.

The board is interesting, although unless you have a special packaging problem, you are probably as well off to combine a Pi and a dongle, as we have seen so many times before. If you have more horsepower you can even make the Pi transmit, although we’d suggest some filtering if you were going to do that for real.

Robotic Arms Controlled By Your….. Feet?

The days of the third hand’s dominance of workshops the world over is soon coming to an end. For those moments when only a third hand is not enough, a fourth is there to save the day.

Dubbed MetaLimbs and developed by a team from the [Inami Hiyama Laboratory] at the University of Tokyo and the [Graduate School of Media Design] at Keio University, the device is designed to be worn while sitting — strapped to your back like a knapsack — but use while standing stationary is possible, if perhaps a little un-intuitive. Basic motion is controlled by the position of the leg — specifically, sensors attached to the foot and knee — and flexing one’s toes actuates the robotic hand’s fingers. There’s even some haptic feedback built-in to assist anyone who isn’t used to using their legs as arms.

The team touts the option of customizeable hands, though a soldering iron attachment may not be as precise as needed at this stage. Still, it would be nice to be able to chug your coffee without interrupting your work.

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Digital Clock Goes with the Grain

This good-looking clock appears to be made out of a block of wood with LED digits floating underneath. In reality, it is a block of PLA plastic covered with wood veneer (well, [androkavo] calls it veneer, but we think it might just be a contact paper or vinyl with a wood pattern). It makes for a striking effect, and we can think of other projects that might make use of the technique, especially since the wood surface looks much more finished than the usual 3D-printed part.

You can see a video of the clock in operation below. The clock circuit itself is nothing exceptional. Just a MAX7218 LED driver and a display along with an STM32 ARM processor. The clock has a DHT22 temperature and humidity sensor, as well as a speaker for an alarm.

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An Education on SoC using Verilog

[Bruce Land] is one of those rare individuals who has his own Hackaday tag. He and his students at Cornell have produced many projects over the years that have appeared on these pages, lately with FPGA-related projects. If you only know [Land] from projects, you are missing out. He posts lectures from many of his classes and recently added a series of new lectures about developing with a DE1 System on Chip (SoC) using an Altera Cyclone FPGA using Verilog. You can catch the ten lectures on YouTube.

The class material is different for 2017, so the content is fresh and relevant. The DE1-SOC has a dual ARM processor and boots Linux from an SD card. There are several labs and quite a bit of background material. The first lab involves driving a VGA monitor. Another is a hardware solver for ordinary differential equations.

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Rusty ARM

You’ve probably heard that Rust is a systems programming language that has quite the following growing. It purports to be fast like C, but has features like guaranteed memory and thread safety, generics, and it prevents segmentation faults. Sounds like just the thing for an embedded system, right? [Jorge Aparicio] was frustrated because his CPU of choice, an STM32 ARM Cortex-M didn’t have native support for Rust.

Apparently, you can easily bind C functions into a Rust program but that wasn’t what he was after. So he set out to build pure Rust programs that could access the device’s hardware and he documented the effort.

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STM32 Analog Converter Phase Noise

[Avian] has been using STM32 ARM processors to sample RF for a variety of applications. At first, he was receiving relatively wide TV signals. Recently, though, he’s started dealing with very narrow signals and he found that his samples had a lot of spread in the frequency domain that he didn’t expect.

What followed was some detective work that resulted in a determination that phase noise was the culprit. But why? [Avian] took some measurements and noticed that the phase noise almost exactly matched the phase noise specification for the STM32’s phase locked loop (PLL).

Unfortunately, there didn’t seem to be a good way to avoid using the PLL without major changes to the rest of the circuit. However, it was quite the learning experience and something to be aware of when counting on built-in converters for high-accuracy measurements.

One of the best things about this post is the references to more information. There’s a great explanation of phase noise, as well as a specific application note about clock jitter and analog converters.

We’ve talked about phase noise in direct digital synthesis a few times. But usually, it is pretty obvious like when you are asking a CPU to double as an RF transmitter. [Avian’s] post was a bit more of a detective story.

New Part Day: The $239 Pi Clone

Linaro has announced a new ARM-based single board computer.

The HiKey 960, built in collaboration with 96Boards, gives the user 4 ARM Cortex-A73 cores clocked at 2.4GHz, 4 ARM Cortex-A53 cores clocked at 1.8 GHz, a Mali GPU (ugh), 32GB of Flash storage, 3GB of LPDDR4, HDMI 1.2, WiFi, Bluetooth, USB 3.0 type A, PCIe on an M.2 connector, and a familiar 40-pin GPIO connector whose configuration is not published yet but is one we can make a very educated guess about. This is a powerful ARM-based single-board computer that’s the same size as a credit card.

This single board computer draws more power than a Raspberry Pi (but less than 24 W with a 12V supply), but that’s what you get when you need a powerful ARM chip. Interestingly, the HiKey 960 places all the connectors on one side of the board. This is a feature very often overlooked in ARM-based single board computers; all the ports on your desktop are on the back, and it only makes sense to constrain the cables and dongles to one side of a Nintendo-shaped 3D printed enclosure.

This is not the first ARM-based single board computer that markets itself as a more powerful Pi. The Pine64 was supposed to be significantly more powerful, handle 4K HDMI, and bring Android to the desktop. The first versions of the Pine64 really, really sucked. However, most of the kinks have been worked out and the folks behind the Pine64 are now shipping a somewhat reasonable low-end Chromebookesque laptop for $89. This is a laptop for under a Benjamin, whereas the HiKey 960 will sell for $239. That’s the same price as an Intel NUC or other mini PC running an x86 CPU. Of course, the HiKey 960 will have higher performance compared to the latest Pi, or other Pi Killer such as the Asus Tinker board, but there must be a point of diminishing returns. Either way, we look forward to getting our hands on one of these powerful single board computers.