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2.c. Configuring the Wixels
Before your Wixels will work with the Wixel Shield for Arduino, they need to be programmed with a compatible app. The Wixels do not ship with an app on them, so you will need to configure them using the Wixel Configuration Utility on a Windows computer. The Wixel User’s Guide contains instructions for downloading, installing, and using the Wixel Configuraiton Utility.
Wixel Shield App
The quickest way to get started with your Wixel shield is to load both Wixels with our open-source Wixel Shield app (25k wxl). This special version of the Wireless Serial app, which is documented in the Wixel User’s Guide, creates a wireless serial link between two Wixels and enables wireless Arduino sketch uploading (using the standard Arduino computer software) in addition to general-purpose wireless communication.
The app has two configuration parameters: radio_channel and baud_rate. Both Wixels need to use the same radio_channel, and the baud_rate needs to be set to the specific upload speed/bootloader baud rate for your Arduino, as shown in the table below. (Other baud rates will work for serial communication, but they will not work for wireless Arduino programming.)
|Arduino board name||Upload speed/baud_rate|
|Arduino Duemilanove w/ ATmega328||57600|
|Arduino Diecimila or Duemilanove w/ ATmega168||19200|
|Other|| Use upload.speed parameter in Arduino
Making Your Own Compatible Apps
Compatible apps, at a minimum, must do two things: relay serial communication and reset the Arduino when the Arduino software signals a reset. To accomplish this, they should use the following three Wixel pins:
- P0_0 – the Arduino is held in reset while this pin is high
- P1_6 – Wixel TX/Arduino RX
- P1_7 – Wixel RX/Arduino TX
The other 12 general-purpose I/O pins including 5 analog inputs are free to be used by your app to interface with the Arduino or other electronics.
A good starting point for making your own compatible app is to modify the source code for the Wireless Serial App, which is available in the Wixel SDK and included as part of the Wixel Development Bundle. The Wixel User’s Guide has more information on making your own Wixel apps in Section 10.