Over the last few months, I’ve noticed extra calls coming in from local numbers, and if you live in the US, I suspect maybe you have too. These calls are either just dead air, or recordings that start with “Please don’t hang up.” Out of curiosity, I’ve called back on the number the call claims to be from. Each time, the message is that this number has been disconnected and is no longer in service. This sounds like the plot of a budget horror movie, how am I being called from a disconnected number? Rather than a phantom in the wires, this is robocalling, combined with caller ID spoofing.
The latest news from the world of cheap electronics is a single board computer running Linux. It costs six dollars, and you can buy it right now. You might even be able to compile code for it, too.
The C-Sky Linux development board is listed on Taobao as an ‘OrangePi NanoPi Raspberry Pi Linux Development Board” and despite some flagrant misappropriation of trademarks, this is indeed a computer running Linux, available for seven American dollars.
This board is based on a NationalChip GX6605S SoC, a unique chip with an ISA that isn’t ARM, x86, RISC-V, MIPS, or anything else that would be considered normal. The chip itself was designed for set-top boxes, but there are a surprising number of build tools that include buildroot, GCC and support for qemu. The company behind this chip is maintaining a kernel, and support for this chip has been added to the mainline kernel. Yes, unlike many other single board computers out there, you might actually be able to compile something for this chip.
The features for this board include 64 MB of DDR2 RAM, HDMI out (with a 1280 x 720 framebuffer, upscaled to 1080p, most likely), and a CPU running at just about 600 MHz. There are a few buttons connected to the GPIO pins, two USB host ports, a USB-TTL port for a serial console, and a few more pins for additional GPIOs. There does not appear to be any networking, and we have no idea what the onboard storage is.
If you want a challenge to get something compiled, this is the chip for you.
Evolutionary algorithms are an interesting topic of study. Rather then relying on human ingenuity and investigation to create new designs, instead, an algorithm is given a target to achieve, and creates “offspring”, iterating in an evolutionary manner to create offspring that get closer to the target with each generation.
This method can be applied to the design of electronic circuits, and is sometimes referred to as “hardware evolution”. A team from Duke University attempted exactly this, aiming to produce an oscillator using evolutionary techniques.
The team used a platform called the “evolvable motherboard”, or EM. The EM is a platform controlled by an attached computer, consisting of reconfigurable solid state switches that allow attached circuit components to be interconnected in every combination possible. These components may be virtually any electronic component; in this experiment, 10 bipolar transistors were used.
The evolutionary algorithm was given a fitness function that rewarded output amplitude and frequency, aiming to create an oscillator operating at 25KHz. However, the team noticed some interesting emergent behavior. The algorithm tended to reward amplification behavior from the circuit, leading to many configurations that oscillated poorly, but amplified ambient noise. In the end, the algorithm developed circuit configurations that acted as a radio, picking up and amplifying signals from the surrounding environment, rather than oscillating on their own. The evolutionary algorithm took advantage of the interaction between not only the circuit elements, but effects such as the parasitic capacitance introduced by the switching matrix and appeared to use the PCB circuit traces as an antenna.
The team conclude that evolutionary algorithms used in circuit design ignore human preconceptions about how circuits work, and will take advantage of sometimes unpredictable and unexpected effects to achieve their targets. This is a blessing and a curse, bringing unconventional designs to the fore, but also creating circuits that may not work well in a generalized environment. If your “oscillator” relies on a nearby noise source to operate, it may operate unpredictably in the field, for example.