dropbot

Firmware for the DropBot digital microfluidics control system and a Python module for communicating with it over a serial connection.

• Install
• Upload firmware
• Conda package contents
• Usage
  • Example interactive session
• Develop
  • Adding new remote procedure call (RPC) methods
  • Set up development environment (within a Conda environment)
  • Build firmware
  • Flash/upload firmware
  • Unlink development working copy
• Contributors

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Install

The latest dropbot release is available as a Conda package from the sci-bots channel.

To install dropbot in an activated Conda environment, run:

conda install -c wheeler-microfluidics -c conda-forge dropbot

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Upload firmware

To upload the pre-compiled firmware included in the Python package, from an activated Conda environment run the following command:

python -m dropbot.bin.upload

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Conda package contents

The dropbot Conda package includes:

• dropbot.SerialProxy Python class providing a high-level interface to the DropBot hardware.
• Compiled firmware binary for the DropBot hardware.

The installed components (relative to the root of the Conda environment) are shown below:

├───Lib
│   └───site-packages
│       └───dropbot (Python package)
│
└───Library
    └───bin
        └───platformio
            └───dropbot (compiled firmware binaries)
                │   platformio.ini   (PlatformIO environment information)
                │
                └───teensy31
                    firmware.hex

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Usage

After uploading the firmware to the board, the dropbot.Proxy class can be used to interact with the Arduino device.

See the session log below for example usage.

Example interactive session

>>> import dropbot

Connect to DropBot:

>>> proxy = dropbot.SerialProxy()

Query the number of bytes free in device RAM.

>>> proxy.ram_free()
409

Query descriptive properties of device.

>>> proxy.properties
base_node_software_version                               0.9.post8.dev141722557
name                                                                    dropbot
manufacturer                                                           Sci-Bots
url                                                                  http://...
software_version                                                            0.1
dtype: object

Use Arduino API methods interactively.

>>> # Set pin 13 as output
>>> proxy.pin_mode(13, 1)
>>> # Turn led on
>>> proxy.digital_write(13, 1)
>>> # Turn led off
>>> proxy.digital_write(13, 0)

Query number of available channels.

>>> proxy.number_of_channels()
120

Query state of all actuation channels.

>>> proxy.state_of_channels

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Develop

The firmware C++ code is located in the src directory. The key functionality is defined in the dropbot::Node class in the file Node.h.

Adding new remote procedure call (RPC) methods

New methods may be added to the Python API by adding new methods to the dropbot::Node C++ class in the file Node.h.

Set up development environment (within a Conda environment)

1. Clone dropbot source code from GitHub repository.

2. Run the following command within the root of the cloned repository to install run-time dependencies and link working copy of firmware binaries and Python package for run-time use:

   paver develop_link
   

3. Restart terminal and reactivate Conda environment (e.g., activate if Conda was installed with default settings).

Step 4 is necessary since at least one of the installed dependencies sets environment variables, which are only initialized on subsequent activations of the Conda environment (i.e., they do not take effect immediately within the running environment).

Build firmware

Run the following command within the root of the cloned repository to build the firmware:

paver build_firmware

The compiled firmware binary is available under the .pioenvs directory, as shown below:

└───.pioenvs
    └───teensy31
            firmware.hex

Flash/upload firmware

To flash/upload a compiled firmware to a DropBot v3, run the following command from the root of the repository:

pio run --target upload --target nobuild

Unlink development working copy

Run the following command within the root of the cloned repository to unlink working copy of firmware binaries and Python package:

paver develop_unlink

This will allow, for example, installation of a main-line release of the dropbot Conda package.

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Contributors

• Christian Fobel (@cfobel)
• Ryan Fobel (@ryanfobel)