We at Pololu are excited to introduce the Wixel shield for Arduino, an easy and affordable way to add wireless functionality to your Arduino or Arduino clone. With the Wixel shield, you get more than just a general-purpose wireless serial link between your Arduino and a remote computer or embedded system: you can also wirelessly program the Arduino using the standard Arduino computer software and wirelessly debug your sketches with the Arduino serial monitor. The Wixel shield duplicates the Arduino's USB interface, allowing you to continue using it as you traditionally would, even after you free it from its USB tether. The shield accomplishes this without interfering with the Arduino's existing USB circuitry, however, so the Arduino's built-in USB interface can still be used while the shield is connected.
The wireless link is maintained by a pair of Wixels: one plugs into a socket on the Wixel shield and the other can be connected directly to a computer via USB (creating a virtual COM port) or to the TTL serial lines of another serial device. This connection has a range of approximately 50 feet under typical indoor conditions. These Wixels can be loaded with an open-source Wixel shield app to allow wireless Arduino communication and programming, or you can write your own, custom Wixel apps to augment your Arduino with their additional processing power, I/O lines, and hardware peripherals.
The shield offers several additional features:
Prototyping space for easier/cleaner construction of custom circuits
Shield-accessible Arduino reset button and pin 13 LED
Four general-purpose 2/3 voltage dividers (can be used to safely connect 5V signals to 3.3V inputs)
Two general-purpose MOSFETs (can be used as level-shifters or high-current outputs)
Wixel socket allows the Wixel to be removed and used for other applications
The shield is $12.95, and it is available with a pair of Wixels for $49.95. For more information, please see the Wixel shield user's guide. Please don't hesitate to ask if you have any questions (either in this thread or on the Pololu forum), and we welcome your feedback!
robtillaart:
What frequency does it use?
Is it allowed to use in all countries? Europe Asia Australia etcetera
The Pololu Wixel is a general-purpose programmable module featuring a 2.4 GHz radio and USB. You can write your own software or load precompiled, open-source apps onto the TI CC2511F32 microcontroller at the heart of the Wixel, turning it into a wireless serial link, data logger, or whatever you need for your current project. With 29 KB of available flash and 4 KB of RAM, the Wixel is even suitable as the main controller for a robot or other system. This version ships 0.1" male header pins included but not soldered in, allowing for custom installations.
robtillaart:
What frequency does it use?
Is it allowed to use in all countries? Europe Asia Australia etcetera
The Wixel radio is low-power and operates in the 2.4 GHz band, which is relatively unrestricted in many parts of the world, but it is your responsibility to comply with your local regulations if you program your Wixel to use its wireless capabilities. Please see section 1.c of the Wixel user's guide for more information.
This is neat -- what sort of modulation does the it support? Is it interoperable with any other types of 2.4 GHz wireless, i.e. Bluetooth, 802.15.4, etc?
Wixels are mainly intended for wireless communication with other Wixels. The Wixel uses the CC2511F32 microcontroller from Texas Instruments, which does not support Bluetooth, 802.15.4, Zigbee, or Wifi. The Wixel is compatible with the CC2500 transceiver, the CC2510Fx family, and the CC2511Fx family of chips from Texas Instruments. All the apps we've written for the Wixel use MSK modulation, but the radio also supports 2-FSK and GFSK modulation. It also supports a wide range of data rates, Manchester encoding, forward error correction, and a host of other options.
if I read this right - it's a replacement for a pair of XBees
or did I read it wrong after all?!?
Not quite. The Wixels are designed just to be used in pairs, while the Xbees can be used in a network of more the two. Other then that they are somewhat equivalent.
It depends what you want to do. Typically, people use XBees to make a wireless serial link between two microcontrollers or between a microcontroller and a computer. You can achieve that with a pair of Wixels without writing any code if you use the wireless serial app, so in that sense a pair of Wixels could replace a pair of XBees and save you money. But please note that the XBees work over a longer range than Wixels.
The Wixels are based on TI's versatile CC2511F32, so they are not inherently restricted to working in pairs. Most of the apps we have available now are designed to be used with pairs of Wixels, but we have some apps (e.g. the I/O Repeater) that allow for many-to-many communications, and you can write your own apps to allow for communication among a network of Wixels, too.
The Wixel is similar to the XBees in many ways, but with the integrated USB, programmable microcontroller, and 0.1" pin spacing, we feel they are a compelling, lower-cost alternative for many wireless projects (and as far as I know, wireless Arduino programming cannot be easily done with XBees).
Oh, I'm sorry I forgot to answer that part of your last post! Whether it becomes available in the UK is up to our UK distributors. We don't have a very good way of tracking which products our various distributors stock, but you can check with them directly:
Because the Wixel shield is so new, I don't think any of them carry it yet, but they might be willing to start if you contact them and request it.
If I run a UNO at 3 volts (2 AA) am I right in thinking I don't need the step up/down level shifters?
hence I can directly wire from UNO D0/D1 to Wixel TX/RX?
If you are interfacing the Wixel with a part running at the same voltage, you don't need shifters. However, I was under the impression the minimum recommended operating voltage for the Arduino Uno is 7 V. Furthermore, according to the datasheet, an ATmega328 running at 16 MHz requires at least 4.5 V to be in spec (you can run it at lower voltages if you keep the clock at 8 MHz or less). Separately, I think you'd be better off boosting a single AA battery to 3.3 V with a regulator or using two cells with a sepic or buck-boost regulator than powering your circuits directly from two AA cells.
I have heard of people running their AVRs above 8 MHz while supplying under 4.5 V without noticing any problems, though they are technically out of spec and who knows what sorts of weird bugs could appear at inopportune moments!
Back on topic, I finally got my seeeduino project taking to the IDE using a pair of wixels.
I followed the user guide (shock horror) and downloaded wireless app 1.3 shield version.
I did have to change the default baud rate to 57600
I also found that a steady red LED seems to keen low voltage AKA time to change the batteries
That is so cool. I have been very tempted to buy a pair of Wixel. The ability to easily change from a IDE to arduino board so that one can upload new sketches wirelessly, or to reconfigure them as a simple arduino to arduino wireless link is sure attractive. I just wish the range was a bit more then 50ft, however maybe they are rating that conservatively?
