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Provides a mechanism to use custom backpacks and firmatas in your nodebots easily and without needing to use arduino or compile firmwares and all their dependencies.

Want to use a ping sensor on your nodebot or play around with neopixels? Plug in your arduino or backpack, install the relevant firmware with interchange and start building that nodebot.

It's as easy as:

interchange install hc-sr04 -a nano -p /dev/tty.wchserial1410

No need to install arduino, no need to find the right firmware - interchange is like npm for your backpacks.

Interchange provides the following:

  • A specification for how backpack devices should behave
  • An installation method for backpack firmware onto target boards to make backpack firmware selection and installation easy.
  • A method of updating select parts of the firmware if required without recompilation.
  • An ability to install Standard or Custom Firmatas to a board.
  • An interface for retrieving information from a backpack firmware.


It is recommended to install nodebots-interchange locally so different versions can coexist as part of projects. If you do this, make sure the node modules .bin directory is on your path, like this:

export PATH=./node_modules/.bin:$PATH

After that just install locally using npm

npm install nodebots-interchange

Or alternatively

git clone
npm install

If you'd prefer to have interchange available to all users globally then do this:

npm install -g nodebots-interchange

Once installed you will have access to the interchange application which will allow you to flash your board with a firmware of choice as described in the usage section below.


In general:

interchange install <firmware> -p <port> -a <board_type> -i <I2C_address> [--firmata [name]]

Where <firmware> is the name of the firmware you would like to flash to the board, <port> is the name of the serial port you want to use, <board_type> is the specific type of board you would like to use and <I2C_address> is an optional parameter allowing you to change the default address of the I2C device.

Note: If you do not supply a port and you have multiple boards plugged in it's unknown which of them will get flashed and configured. Best to be specific or only do this while there's one board plugged in. To use avrgirl's @noopkat phrase "without a port, Arduino Roulette will occur".

Using the --firmata switch will attempt to download and install a custom firmata instead if this is available.

As a convenience, if you would like to install StandardFirmata you can do so by:

interchange install StandardFirmata -a <board> -p <port>

For an interactive interface that will prompt you with choices for each option, use

interchange install --interactive

Interactive CLI demo

Usage examples

Get help:

interchange --help

List the firmwares available and get details about them, including whether they are firmata capable or not.

interchange list

Get a list of all the available serial devices you can see (use the --verbose switch if you want to get much more detail about the devices.

interchange ports [--verbose]

Install the HC-SR04 backpack firmware to an arduino nano on port /dev/tty.wchserial1410. (Ensure configuration mode is set on the arduino)

interchange install hc-sr04 -a nano -p /dev/tty.wchserial1410

Install the HC-SR04 backpack firmware to an arduino nano on port /dev/tty.wchserial1410 however change the default I2C address to 0x65 instead. (Ensure configuration mode on the arduino is set).

interchange install hc-sr04 -a nano -p /dev/tty.wchserial1410 -i 0x65

Install StandardFirmata on an arduino Uno at port /dev/tty.usbmodem1230

interchange install StandardFirmata -a uno -p /dev/tty.usbmodem1230

Install the HC-SR04 custom firmata on an arduino Uno at port /dev/tty.usbmodem1230

interchange install hc-sr04 -a uno -p /dev/tty.usbmodem1230 --firmata

Install a custom firmata (in this case for the mbot) onto an arduino from a git repository and not from the interchange directory (good for testing in development) on port /dev/tty.wchserial1560

interchange install git+ -p /dev/tty.wchserial1560 -a uno --firmata

Install a named custom firmata (in this case the mbot Bluetooth firmata) onto an arduino from git repo on port /dev/tty.wchserial1560 - note the use of --firmata [name] here.

interchange install git+ -p /dev/tty.wchserial1560 -a uno --firmata bluetooth

Install the HC-SR04 backpack code on an arduino nano from a named branch on a git repo (very handy for testing when you're in dev) on port /dev/tty.wchserial1560

interchange install git+ -p /dev/tty.wchserial1560 -a nano

Read the details of a backpack firmware on /dev/tty.usbmodem1130 to see what is on it.

interchange read -p /dev/tty.usbmodem1130

Building your own interchange package.

If you want to build your own interchange package you can get more information in the developer guide.


If you are interesting in contibuting, please read the dev getting started guide.

Additional documentation:


Interchange was born of an idea that came out of RobotsConf 2014 that started with a discussion about how to incorporate NeoPixel support into Firmata and Johnny-Five. Adding custom additions to firmata created numerous problems, not just with the bloat that it would cause in firmata but additionally the support requirements it would impose on other IO Plugins as any custom instructions would then need to be supported as well.

The end solution was to instead create a custom NodeBots "board", in the style of a "BackPack" (as used by AdaFruit & others in the hardware space) that would act as a bridge between "dumb" devices such as ultrasonic sensors, neopixels and touch screens that would then expose these components as I2C devices. In this way, any nodebots capable board that can talk I2C (just about all of them) would be able to work with these components, not just those running firmata.

As the project has developed, it was determined that being able to use it to eliminate the need for Arduino for beginners was also useful and would use the same mechanism.

This project would not have seen light were it not for the following people:

  • Rick Waldron - believing this was a good approach and supporting the exploration of the idea to augment Johnny Five.
  • Suz Hinton - for the excellent avrgirl which provided considerable heavy lifting on the flashing side of things.
  • Derek Wheelden - for tuning the experience of the way Interchange has worked to make it more usable.
  • Andy Gelme, Luis Montes - for pushing me on backpacks and keep me moving.