Carambola

Lietuvos company 8devices makes Carambola 1 and 2 modules, as shown in the picture. The smaller module is Carambola 2.


Carambola 1, built around RT3050, is under replacemant with 2, built around AR9331. Carambola 2 is a minimal interface between a BGA packaged chip and the average hobbist. The module is very small, 38 mm x 28 in size, and includes CPU, with integrated wi-fi, flash and ram. OpenWrt is preinstalled. Price is "chinese", very cheap. It looks like a big SMD chip, ready to be soldered on a PCB. Pin pitch is 2mm, well within hobbist capability. Moreover it is a board, with good thermal separation between solder tip and chips. In the picture the module, seen without RF shield.


Taking into account ESD protection, soldering is well in the possibilities of an average hobbist. Availlable interfaces include a 3.3 volt serial, acting as a console, two Ethernet ports (LAN and WAN) without Phy. Wi-Fi has two outputs: a pin to be soldered on a trasmission line on the PCB, and an UFL connector. As tested, both works very well, but do not connect both simultaneously. This would mismatch paralleled antennas ! Finally there is USB, well supported from operating system and working without problem. Pendrive are supported, hubs are supported, and UVC (USB video class) webcam, after installation of application software, are supported. Video stream and pictures can be trasmitted via Wi-Fi. 8devices site hosts a lot of software OpenWrt modules recompiled for AR9331 and tested. Finally some GPIO microcontroller-like pins ara available, Some of them can be reconfigured as SPI. For CS (chip select) reason a microSD can not be connected immediately, because interferes with boot flash, and preinstalled OS must be sysupgraded. Obviously all interfaces are without connettors, duty left to final application PCB. 8devices sells also a small development system, including Carambola 2 (unfortunately soldered) a voltage regulator, and all necessaries connectors and Phy. A FTDI USB-serial converter is also installed. This way is possible to have from a PC power supply and a virtual serial console, and Carambola USB is free to work as host for peripherals. The development system is shown in the picture.


The intrinsecally shielded structure of Carambola maked it ideal for my dream, an onboard computer for a CubeSat. His small size can fit also in a PocketQube. For the beginning Carambola 2 module is the heart of Belinonda 4 , the wearable Internet Wi-Fi site.

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