How do I connect Arduino to a Bluegiga112?
The most popular way to establish communication between an Arduino (I've used a Duemilanove) and a BLE module (I've used BLE113 that's on a DKBLE113) is through UART.

UART is a two wire interface (don't forget the common GND) with one RX and one TX.
You can use the SoftwareSerial library to define your communication object on the Arduino.
In contrast, the BLE113 uses four. The additional two are RTS and CTS (Request To Send and Clear To Send).

However, you can configure the UART in two ways using hardware.xml:


Go to the &lt;usart > tag and set flow = "false". This "disengages" the RTS and CTS allowing a traditional two wire interface.
Had you set flow = "true", you need to connect the RTS and CTS as well, which I had a big problem with, though the two are both digital.


Further, in hardware.xml, you need to disable sleep mode by including &lt;sleep enable="false" /> within the &lt;hardware> tag. This will solve all your problems.
If you intend to use sleep mode, you need to skip the previous step and instead govern the module's mode through the P0_0 pin. Moreover, there are additional definitions to be included in hardware.xml, which are documented by BG. These work nicely for the BLE112 too.

In my exercise, I'd established communication at 9600 baud. It worked the same way when I increased it to 115200 baud (this is a plus in the BLE113).