A13AA - Miniature Number Hammer for Embedded Applications

Recently, a suggestion was made at Habré that no one has yet made a system based on Allwinner AXX. Well, welcome.

Introduction

The board based on the Chinese Allwinner A13 megapopular processor, unpretentiously called us A13AA, is intended for use as the basis for a variety of control systems that require both compact dimensions with the possibility of battery power and high computational capabilities. The board carries onboard a processor with an operating frequency of 1GHz, 256MB DDR3 RAM, and (optionally) 4GB flash memory.





The choice of processor is due to its low price and a good set of peripherals. In the shortcomings - a small prevalence in Russia (precisely for the purchase of chips, and not in the composition of the tablets) and frankly weak documentation. We can put up with the drawbacks, in the bottom line we have an attractive chip.

New boards appear like mushrooms after rain. Here, and Cubieboard , and Virt2real , and Wirenboard , why another? The A13AA has several differences. Firstly, the board is made as compact as possible, its thickness is 5.5 mm (and without a mini USB connector - only 3.2 mm!). True, in the version with built-in flash memory, these figures increase by 2 mm, but even this does not prevent the board from remaining almost the lowest profile among similar ones. Secondly, the board has a powerful power supply system based on the AXP209 chip, designed specifically for Allwinner processors. In addition to the standard set of voltages of 3.3V and 5V, 4 individually adjustable output voltages are available to the user. There is also a charging circuit for a lithium battery, so the task of connecting an external battery comes down to soldering it to the correct contacts. Third, the user has access to a variety of I / O ports that support interfaces such as USB, SPI, I2C, USART, SD, CSI (camera interface), an interface for connecting a display (18-bit). Among them are two UEXT connectors supported by Olimex and offering a mass of expansion cards. Fourthly, the goal was originally made to make the price of the board not only affordable, but generally adequate. As far as we are close to this goal to judge you, the price forecast is 990 rubles in the version without flash and 1290 rubles with 4 GB flash memory on board.

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For whom A13AA

The board will definitely suit you if you are constructing your device for manufacturing in one or several copies, are familiar with Linux or android (or are ready to start the processor without an OS), are not afraid to make your motherboard, if necessary, and rest on the limitations Traditional AVR and STM32 or consider other solutions redundant. The fact is that it is impossible to dissolve A13 with DDR3 memory on a double-layer, and four layers immediately seriously increase the board's manufacturing budget, which is not applicable for DIY projects, and the design complexity is above average. Now, it will be possible to take A13AA, place the basic board on a simple two-layer (yes, even a single-layer, why not!), Put buttons, indicators, connectors, and add a LCD to the touch screen, a camera and a battery to taste. Well, if the baseboard is not needed, then the A13AA will work perfectly alone, in order to run it, you only need a mini-USB cable (and a micro SD card - in the version without a flash). The board already has a mini-USB connector for power and debugging, a slot for a memory card and three hardware buttons - power, reset, uboot. This will certainly be appreciated by students and teachers, electronics engineers and programmers, and simply enthusiasts. The board may also be of interest to designers of the onboard equipment of both the UAV, and wheeled and waterborne vehicles. Whether to organize the transfer of the image from the onboard camera via wi-fi, whether to record it on a memory card, whether to process the signals from the sensors - the board is capable of all of this, only connect wi-fi.

Who is not suitable for A13AA

Definitely not suitable for those who need SATA, HDMI, Ethernet. This is not and never will be. These interfaces complicate, increase the cost of the board, increase the size, if you need them, choose a different board, of which there is now enough. Also, it is not necessary to lay our board in a serial project, well, everything is clear, it is more profitable for a mass product to make its design.

Comparison with competitors

It is not entirely correct to call classmates competitors, on the contrary, we tried to occupy a niche as remote as possible from existing solutions, which is why it is positioned as embedded (embedded), and not at all as a small computer. And we are not going to compete, for example, with Cubieboard. But we can do some comparisons.

Cubieboard and MK802 are the closest to our well-known A13AA. Close in composition, but not as intended. They are built on the basis of A10, I remind you that this is the elder brother of A13, it is distinguished by the presence of HDMI, a large number of ports and some trifles. MK802 is all good, but does not have a GPIO, disappears. Of course, it can be combined with the Arduino, but this duet smells like a crutch-building, moreover, it is more expensive. Cubie is more interesting, this board has a whole gigabyte of RAM, SATA, 3xUSB, HDMI. But, as is usually the case, the disadvantages are a continuation of the merits, all this vast economy consumes more, takes up more space and is again more expensive. In addition, Cubie completely deprived of the ability to charge the battery. In fact, it is optimal as a mission control center for stationary objects with reference to the outlet, external disk and Ethernet.

The closest counterparts are the A13-based Olinuxino-micro and Olinuxino boards . The first one doesn’t have a power management chip, which is not so economical and doesn’t support battery power, besides, it doesn’t have flash memory at all. The second has twice the RAM - 512MB, built-in hub for 3 USB, can be powered from an external source with a wide voltage range. All this is not bad, but it takes up space, consumes energy, and most importantly, it costs money, TAM is 35..55 euros, and HERE is even more in rubles, and it is rarely available.

Malinka remained for sweetness. $ 25 is a strong bid, plus wide promotion and support, small size. But there are downsides. It’s impossible to buy a pie in Russia for this money, and it’s hard to call this board built in, there’s no battery life and a lower clock frequency.

As you can see, in some exceptional cases, A13AA is irreplaceable, and the price, taking into account Russian conditions, is generally the lowest of all boards that are somewhat similar in computational capabilities.

Special features

The fee is based on Olimex OLinuXino, honor and praise them, without these soulful Bulgarian our brothers, our project would hardly have taken place.

Board dimensions are 78.8 * 64.8 mm, wiring is made in four layers. On the edges of the board there are contact pads with holes for double-row PLD pins with a pitch of 2.54 mm, in common words “comb”. A smaller pitch would be more convenient, but the type used is ubiquitous and cheaper than others. The boards are planned to be delivered without pins, so that you yourself can solder them to any side of the board and at the same time save a little. For those who do not want to mess with a soldering iron saving every penny, consider the question of the delivery of the board with the pins installed. The pins allow you to either solder the board to another board with a “sandwich”, or connect a flexible cable with an IDC connector, which is simply assembled from a ribbon cable and the connector itself, by crimping, even without a special tool. This connection is used in the IDE standard, or rather, in the old version with a 40-core cable. Of course, nothing prevents you from soldering the necessary wires directly into the holes, this option can be useful for installation on objects subject to vibration. There are five such connectors in total. One 60-pin combines the interface for the camera and LCD. Two ten-pin ones are UEXT interfaces (one of them with limitations). One eight-pin contains power pins. And finally, one 40-pin is filled with the remaining GPIO lines, audio input and output, two USB channels (one of which is combined with a mini-USB connector installed on the board), pins duplicating buttons placed on the board, as well as ADC input to connect other hardware buttons and other necessary signals.

Questions and answers

Why only 256MB of RAM?

Let's see, and it is not enough? For a personal computer and even an ordinary smartphone, this is really not enough, but for embedded applications, the set of applications is usually limited and, on average, the needs of the majority fit into tens of megabytes. More is needed only for a certain class of tasks, heavy video processing, high-resolution photos, databases, games. All this is typical for desktop applications on hardware that have not only a processor, but also disk and network interfaces in order to receive these volumes from somewhere and send them somewhere, and this is not our case. In addition, one DDR3 chip consumes more than 200mA at its peak, which is quite a lot for a battery device and doubling the memory doubles the consumption, even if the memory is not used by applications. And finally, WirenBoard, for example, has “only” 64MB which does not prevent it from existing.

What is the power consumption of the system?

According to Olimex, at a frequency of 1GHz, the system consumes 2W, in sleep mode 3mA from the battery.

Why is the old single-core A13, because there is already a quad-core A31?

The answer is quite simple - the price. In addition, very few embedded applications require multi-threading, so multi-core for them is redundant. There is still a small nuance, the A13 comes in a package with conclusions, which reduces the cost of installation in small batches, and since we are not going to release a board in the millions, this also matters.

What are the expansion modules and where to get them?

The Olimex website has a rather large list of various modules. Prices are too big, so if there is a demand, we will make the most demanded counterparts cheaper.

How to purchase?

No way yet. Actually, the project is done primarily for its own needs, however, it would be ugly not to share with the community the results of labor. In this regard, there is no pre-order. When the boards become available, we will be able to offer to purchase them immediately, the estimated time is August 2013. In the meantime, we consider it necessary to inform about the fact and to be patient.