We are excited to add another product to our growing Adafruit Bluefruit line, this time it's the Bluefruit EZ-Link Shield: the best Bluetooth Serial shield ever made. Like you, we have purchased all sorts of Bluetooth shields with high expectations - we just wanted something that worked! But nothing ever did exactly what we wanted: there was always some configuration modes to wade through, and trying to reprogram an Arduino is impossible.
So we did what we always do, we went in and engineered something better. Something that works!
he Bluefruit EZ-Link shield is a regular 'SPP' serial link client device, that can pair with any computer or tablet and appear as a serial/COM port (except iOS as iOS does not permit SPP pairing). But here is where it gets exciting: unlike any other BT module, the EZ-Link can automatically detect and change the serial baud rate. That means if you open up the COM port on your computer at 9600 baud, the output is 9600, 57600? 57600. Yep even 2400. All the most common baud rates are supported: 2400, 4800, 9600, 19200, 38400, 57600, 115200 and 230400. You never have to configure or customize the module by hand - it all happens completely automatically inside the RF module.
Now if we stopped there, you'd probably think "wow that is pretty nice" but we didn't stop there! The EZ-Link has another impressive feature: the DTR/RTS/DSR flow control pins are automatically synced to the computer serial port. What this means is that if the computer sets the hardware flow control DTR or RTS pins high or low the pins on the bluetooth module will follow. If the DSR input pin is brought high or low on the EZ-Link, the computer can detect that as well. Every other Bluetooth SPP device we've ever seen, if they even have the RTS/DTR pins brought out, do not sync back to the computer, instead the flow control is for the module serial buffer itself.
Works great with Mac and Windows computers. Linux is not supported at this time.
Together, this creates something pretty amazing: a Bluetooth shield that can change baud rates on the fly and toggle the DTR pin as desired. What we've got here now is a way to program an Arduino (or compatible) from 10 meters away, completely wirelessly, with no extra software, custom hardware, odd firmware hacks or modified firmware. It works great, and you can use the serial console as well. It's the only Bluetooth shield that has completely transparent Arduino re-programming & communication capability
To round out the design we also added two RX/TX indicator LEDs so you can tell when data is sent & received as well as a connection status breakout pin. When the paired computer opens up a UART connection, the status pin goes high, letting the Arduino know that it can now expect data to be sent and it's also OK to send data to the computer. You can use the shield in either Direct mode (the Bluetooth module replaces the USB/Serial chip) or in Soft Serial mode (you still want to program over USB but will use SoftwareSerial to communicate with a computer or other device).
Works great with Arduino Uno/Duemilanove/compatible and Mega. Not for use with Leonardo (the Leonardo uses direct-USB instead of USB-Serial) or Due.