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Komby ‘Sandwich’

This is a set of instructions to get an E1.31-based Komby transmitter working. You will be expected to have completed the Minimalist Shield build before starting here.

Before starting, make sure you have all the parts you need; see below. While an Arduino Duemilanove is illustrated, any Arduino model that supports shields should work. Also, you will need to have downloaded and installed the latest RFShowControl sketches, available here.

Step 1:
Not shown below: a 5- to 9-volt power supply such as a wall wart; if using a wall wart, make certain it provides at least 1 amp of power.

The items needed to make a Komby Sandwich: upper left, the Nordic transmitter (in this case a PA/LNA with an external antenna); upper right, the Minimalist Shield; lower left, an Arduino Ethernet Shield; lower right, an Arduino Duemilanove.

Step 2a:
You will need a MAC address for Ethernet connectivity to work; as seen below, recent models of the Arduino Shield come with a MAC address on a sticker on the underside of the board. In the event your Ethernet Shield does not have a visible MAC address, you can create a fictional one. If you are setting up multiple Ethernet Shields and need a fictional MAC address, create new ones for each shield, do not attempt to share. Write down this address for use in Step 8.

Arduino Shield MAC address on sticker.

Step 2b:
Find the RF_Out_Rainbow_Test sketch in the Arduino IDE's File -> Examples -> RFShowControl directory and open it. Only one item needs to be changed here, the NRF_TYPE, which should become MINIMALIST_SHIELD.

Note the yellow text above, where the NFR_TYPE has been changed to MINIMALIST SHIELD.

Step 3:
Place the Ethernet Shield atop the Arduino; line up the pins on both sides as well as the six pins toward the back.

Ethernet Shield going onto the Arduino.

Step 4:

The Ethernet Shield atop the Arduino.

Step 5:
Care must be taken in placing the Minimalist Shield onto the Ethernet Shield; the printing on the board reads right-side up when the Ethernet connector is pointing down. The Minimalist Shield is installed into the last pin of the female connectors on both the right and left (on the right side, the first male pin is in the third female slot).

Minimalist Shield attached to the Ethernet Shield.

Step 6:
Test the Sandwich to make certain 3.3 volts DC are getting to the nRF header slot marked 3.3v. Either plug in a USB cable to the Arduino or use a 5-volt power supply.

Testing the Sandwich with a digital meter.

Step 7:
With the nRF PA/LNA, antenna, Ethernet cable and power cable attached, the completed Komby Sandwich should now be transmitting test data. Put some sort of lights onto an RF1, RF1_12v or Kombee and see if they work.

The completed Komby Sandwich with the nRF PA/LNA, antenna, Ethernet cable and power cable attached.

Step 8:
Disconnect the Ethernet cable and the power cable. Connect a USB cable to the Arduino's USB port.

Go back to the Arduino IDE application and open the sketch at File -> Examples -> RFShowControl -> RF_Out_E131_In.

You will have to make at least two changes to the file as shown below in yellow; the MAC address and the IP address.

The MAC address should already be in hexadecimal, so you will change only the third and fourth characters in each four-character group; from the Ethernet Shield MAC address displayed on the picture of the board above, the result would look like

0x90, 0xA2, 0xDA, 0x0E, 0xCA, 0x2F

Every hobbyist's home computer network is going to be different, so a single set of instructions to figure out what IP address to assign the Ethernet Shield is difficult. If your show computer connects to the Internet only via an all-wireless network, you will have to determine how to bring online the physical Ethernet port, a task that is really beyond this guide.

But if your show computer is already wired to a network, you can take a stab at figuring out how to assign a good IP address to the Ethernet Shield. Instructions are provided by Microsoft and third parties for determining the IP address of your show computer for Windows 7 and Windows 8. In most versions of Mac OS X, the IP address is available at Apple -> System Preferences -> Network. If you own a Linux or other Unix system, you probably know more about networking than the author of this guide.

Once you have figured out the IP address of your show computer, you can make a wild guess about what address to assign the Ethernet Shield.

IP addresses are expressed as four individual numbers separated by periods that range from zero to 255; so a typical IP address might be something like The creators of the Internet, though, reserved a series of numbers especially for home and office networks, the range is to

The IP address of your show computer using the above procedure is probably something like or or

To give your Ethernet Shield an address, just change the last number in the IP address of your show computer. For example, if your show computer's IP address is

Then perhaps you should assign the Ethernet Shield the address

A number that is sufficiently different so that it probably isn't already taken by other devices on your network but not larger than 255.

The Arduino Ethernet Shield E1.31 Transmitter sketch with the two number sets that must be updated.

You can then load the sketch into the Arduino, unplug the USB cable, plug in the Ethernet cable and the power cable and then visit all the devices that are on your home's wired network. Reboot the computers or printers and if they come back with an error message complaining that their IP address is already taken, then you know you stepped on an existing IP address.

Go back to the Arduino, unplug everything, plug in the USB cable, change the IP address in the sketch to another number, load the sketch into Arduino, unplug the USB cable, plug in the Ethernet and power cables and then go around to all your wired-network devices and reboot them. If none complain, then you should be fine; if not, repeat trying another IP address.

Sorry if this is complex; if it were easy then all your neighbors would have wireless holiday lights.