Build Instructions

Collapse

• 1

  Example driver

  The following summarises how a driver could be structured, it uses the 'hello world' hardware example describing an LED control on a Raspberry Pi.

  Indipydriver provides classes of 'members', 'vectors' and 'devices', where members hold instrument values, such as switch and number values. Vectors group members together, with labels and group strings, which inform the client how to display the values. 'Devices' hold a number of vectors, so a single device can display several groups of controls.

  The 'IPyDriver' class holds one or more devices, and provides methods you can use to send and receive data, which you would use to interface with your own code.

  You would create a subclass of IPyDriver and override the following methods.

  async def rxevent(self, event)

  This is automatically called whenever data is received from the client to set an instrument parameter. The event object describes the received data, and you provide the code which then controls your instrument.

  async def hardware(self)

  This is called when the driver starts, and as default does nothing, typically it could be a contuously running coroutine which you can use to operate your instruments, and if required send updates to the client.

  async def snoopevent(self, event)

  This is only used if the device is monitoring (snooping) on other devices.

  The indipydriver package also includes an IPyServer class. Having created an instance of your IPyDriver subclass, you would serve this, and any other drivers with an IPyServer object:

  server = IPyServer(*drivers, host="localhost", port=7624, maxconnections=5)
  await server.asyncrun()

  A connected client, such as indipyterm, can then control all the drivers. 

  
  
  
• 2

  Install indipydriver

  Generally you would install from Pypi into a virtual environment.

  If you are trying this on a Raspberry pi, you may want to use your system gpiozero package. In which case, when creating the virtual environment, use the --system-site-packages option to allow your script to use system packages:

  python3 -m venv --system-site-packages my_env_directory
  
  source my_env_directory/bin/activate
  
  pip install indipydriver

• 3

  Define your instrumentation objects

  You would initially start the script by defining your own classes. In this example an LED will be controlled:

  import asyncio
  import indipydriver as ipd
  
  # from gpiozero import LED
  
  # If trying this on a raspberrypi, uncomment the line above
  # and comment out or delete this simulated LED class definition
  
  class LED:
      "A class to simulate gpiozero.LED"
  
      def __init__(self, pin):
          self.pin = pin
          self.is_lit = False
  
      def on(self):
          self.is_lit = True
  
      def off(self):
          self.is_lit = False

View all 8 instructions