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A simple library for serial port communication with Clojure. Although serial communciation may be considered old tech, it's useful for a communicating with a plethora of devices including exciting new hardware such as the Monome and the Arduino. It's powerd by [PureJavaComm] ( for serial communication


Add the following to your project.clj dependencies:

[clj-serial "2.0.5"]


Using the library

Just make sure you pull in the serial.core namespace using something like:

(use 'serial.core)

Finding your port identifier

In order to connect to your serial device you need to know the path of the file it presents itself on. serial.util provides a simple function to list these paths out:

=> (use 'serial.util)

=> (list-ports)


In this case, we have an Arduino connected to /dev/tty.usbmodemfa141.

Connecting with a port identifier

When you know the path to the serial port, connecting is just as simple as:

(open "/dev/tty.usbmodemfa141")

However, you'll want to bind the result so you can use it later:

(def port (open "/dev/tty.usbmodemfa141"))

Reading bytes

If you wish to get raw access to the InputStream this is possible with the function listen. This allows you to specify a handler that will get called every time there is data available on the port and will pass your handler the InputStream to allow you to directly .read bytes from it.

When the handler is first registered, the bytes that have been buffered on the serial port are dropped by default. This can be changed by passing false to listen! as an optional last argument.

Only one listener may be registered at a time. If you want to fork the incoming datastream to a series of streams, you might want to consider using lamina. You can then register a handler which simply enqueues the incoming serial data to a lamina channel which you may then fork and map according to your whim.

Finally, you may remove your listener by calling unlisten! and passing it the port binding.

Writing bytes

The simplest way to write bytes is by passing a byte array to write:

(write port my-byte-array)

This also works with any Number

(write port 20)

As well as any Sequential

(write port [0xf0 0x79 0xf7])

Closing the port

Simply use the close! function:

(close! port)


  • Peter Schwarz

Forked from samaaron/serial-port, by

  • Sam Aaron
  • Jeff Rose


Distributed under the Eclipse Public License, the same as Clojure.

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