Bluefruit EZ-Link

The Bluefruit EZ-Link 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.

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. Other Bluetooth SPP devices, if they even have the RTS/DTR pins brought out, do not sync back to the computer, but instead the flow control is for the module serial buffer itself.

Together, this creates something pretty amazing: a Bluetooth module 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. In fact, you can use the Bluefruit as a sort of 'wire free' FTDI-like cable with any device that has an FTDI re-programming port. It works great, and you can use the serial console as well. This package includes the necessary 1uF capacitor between the DTR and reset pin.

To round out the design there are also two RX/TX indicator LEDs so you can tell when data is sent & received as well as a connection status pin. When the paired computer opens up a UART connection, the status pin goes high, letting the microcontroller know that it can now expect data to be sent and its also OK to send data to the computer.

Each order of this EZ-Link + Extras pack includes one ready to go and assembled EZ-Link board, with FCC/CE/RoHS certification. A 6-pin right angle female header is also included, along with a stick of 6-pin extra-long male header. Chances are you will want to solder the female header in to the center of the board so you can use it like an FTDI-cable but you have the option of wires, or other kind of header. A JST connector is also included. The JST connector can be soldered on the back (optional) to connect a Lipoly battery for portable projects. If the JST is used, the battery can also power the microcontroller that the EZ-Link is plugged into.

• Dimensions: 20.4mm / 0.8" x 41mm / 1.6" x 4mm / 0.2"
• Weight: 4.35g

Additional usage details available in the Adafruit Learning System.