CubieBoard is expensive, Raspberry Pi is rather weak, or where can I get SoC with a GPIO better and cheaper

Raspberry Pi became a popular single-player card almost immediately after its appearance, as there were no cheaper, smaller, and universal SoC systems. However, now the time has come when the Chinese are releasing cheap and compact SoCs like AllWinner A10 with a frequency up to 1.2 GHz, which look noticeably more tempting than the 0.7 GHz raspberry pie.



There is of course CubieBoard which seems to have everything that the developer may need in principle, and a more powerful processor than the RPi, although single-core, but the Cortex A8 1.2 GHz, and it has Gig operatives, and there is a SATA port, and in general probably He wins all of RPi, except for the lack of analog video, but he has one drawback. If the RPi officially costs $ 35, although it is possible to buy the official RPi from a dealer in Russia to which of.site only for 2500 p. then at least he has a Chinese copy on ebay for $ 40, while CubieBoard officially comes from China, but its price on ebay is $ 83, and having 2 less powerful RPi is more attractive to me than one powerful CubieBoard, and even 100 rubles for beer batteries will remain.



However, there is a Chinese hero, ready to lie on the sharp picket fence of contention between the powerful processor and cheapness. However, it is completely unsuitable for most projects for which the machines described above are sharpened. He was also recognized as popular, for its price and power, but in a different class of devices, in the class of silent home media servers, his name is MK802. Not once described on Habré, and on the whole Internet, Android miniPC MK802 with the ability to boot Linux from a microSD card puts it on a par with the power of the processor with CubieBoard and accordingly higher Raspberry Pi, but it has the main drawback - no GPIO . It almost puts an end to the possibility of using it as a powerful processor, say for the brains of a robot, or the system of a smart home.

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But it has a USB Host, but not one, so why not see the USB-GPIO adapters? However, the result is not very encouraging. Basically, such devices are the prerogative of FTDI, which produces wonderful devices and modules, for example, the following would be ideal:





However, there is a snag, the price. For example, here it stands like the MK802 itself, but it was not possible to find it cheaper.



But. What Durin not GPIO? After all, the cost of Arduino Nano on ebay is only 350 p.



Of course, evil tongues will say, but why then in general MK802? Well, I’m silent about the processor, indeed, for most projects, Atmega328 is enough for the eyes, but at least take the first two glaring features, WiFi and USB host. To connect them to the Arduino, you need two modules that cost 550 r for the cheapest USB host and 1800 r for the same WiFi shield, all together it will cost about 2800 r and look something like this:







Well, in all respects, no competitor to Cubieboard. Whereas the MK802 + Arduino nano is 1500r, and the following parameters:





Among other things, in terms of size, the MK802 outperforms its competitors; this can be an important factor, say, for an aircraft model maker who wants to install a webcam on their quadrocopter and control it via WiFi. Having an Arduino does not greatly increase the thickness of the RPI and CubieBoard compared to the RJ-45 connector. But the Arduino takes a USB port, or rather a miniUSB port. On the MK802, one of the USB host ports is made in this form factor, it is probably more appropriate to use it. Something like that.





Although it is more logical to pull out both miniUSB connectors, and drill a couple of holes in the case to connect them with 4 short wires.



And here the main question for the sake of which the topic is created emerges. Arduino Nano has an ATMega 328 processor with a body kit (quartz, passive elements, LEDs ...) and an FDTI USB-UART converter chip. But the question is, why do we use USB twice? Not all Allwinner crystal pins are displayed on the MK802 board (for example, there is no Line-in audio, which is regrettable), but the UART is derived in the form of 4 circular copper pads near the SoC which are not soldered only by the lazy one.







This UART has a console for debugging dead devices. But you can get to the console from the axis (if your device is loading, of course) And there are descriptions on the Internet how to use these pins, instead of the console, you can connect an IRDA receiver. Is it possible to force it to flash ATMega328? Well, for example, with the Arduino bootloader. At the very minimum, we will take this device by the name of Arduino mini:



What is just a divorced percent with Arduino bootloader and quartz. It costs 150r (as usual on ebay). The pins of interest to us, by the way, are displayed on the left (in the picture) edge of the board.



So here. The process of uploading a sketch from a computer to an Arduin, is sending a spec. commands to the UART input of the Arduino at the time of its loading, followed by sending a compiled sketch to the same UART. The logical question is how to make the Arduino IDE for Linux perceive the UART as a COM port, and how can you reload the arduino programmatically? Let's say an LED, or some other indication indication, to use as a GPIO for a reload pulse. Or is it all not too real? Question to experienced Linux and ARM.



After all, if this is realizable, then we get for a maximum of 1300 r, i.e. at the price of a Chinese copy of the Raspberry Pi, a smaller machine, with a more powerful processor, memory, built-in WiFi and other, 2 free USB, 22 GPIO, and since the ATMega328 (and maybe Arduino mini) fit inside the MK802, device



Hang a cheap webcam on it, soldering to its shortened miniUSB connector cable, on the GPIO hook up propellers, flaps, wheels, propeller, fins, taps, solenoids, or electric mop drive, and you have a home or field robot, helicopter, boat, self-propelled, vacuum cleaner, watering device, manipulator, security system or anything with a server, configurable from work, business trips, and anywhere on the Internet and Wi-Fi. For 1300 rubles. but with the power of not the most top-notch laptop, the power consumption of charging from the iphone, and the noiselessness of the rock garden. I put it on a helicopter, stuck 3G modem into a free USB port, and flew over the cottage to fly, and he distributes the acquired Internet via WiFi, you have fun, the wife checks mail (this is of course a joke, but in the style because we can).



About the IR port here and generally a lot of useful.

Pictures, except for self-searching from google search on tags “MK802, Arduino” and from FTDI website



UPD



Approximate prices are taken from Ebay.com, just in case, I’ll point out where exactly, but I apologize in advance if the listings expire, as was the case with a copy of RPi for $ 40, which I now do not find, but instead it appeared for $ 35. In general, these prices are valid at the time of this writing, delivery is designed to Russia.



Raspbery Pi Here is a copy for 1100r ($ 35 promised to copyright holders) Here for 1300r .



CubieBoard Here is the cheapest kit with delivery that was found 2600r .

But later in the comments neepolas suggested that here the device itself for the action costs $ 50, and delivery costs $ 10, respectively, now the cheapest Cubieboard costs 1800r , not twice, but still more expensive than RPI and MK802.



MK802 1GB RAM for 1300r .