Driver for Virtual Device out of piCtory

 We use RevPiModIODriver() to develop a driver for a virtual device in piCtory.

In our example, we collect data from the RevolutionPi and write it into a virtual device. This is the system time in UTC, the percentage of disk space, and the CPU temperature.

Source code for RevPiModIO Version 2

# -*- coding: utf-8 -*-
import revpimodio2
import time
from os import statvfs


class MyDriver():

    def __init__(self):
        """Instantiates the driver."""

        # Instantiate RevPiModIODriver for virtual device on position 64
        self.rpi = revpimodio2.RevPiModIODriver(64, autorefresh=True)

        # Handle exit signal from operating system or Ctrl+C Signal to exit
        # the driver cleanly
        self.rpi.handlesignalend()

        # RevPiModIODriver: Configure inputs to write data
        # We are the DRIVER an CAN write into INPUTS!!!

        # Use Input-Byte 0 to 3 as int for timestamp
        self.rpi.io.Input_1.replace_io("timestamp", "L")

        # Input byte 4 as int use for n% allocation root mount
        self.rpi.io.Input_5.replace_io("roothdused", "B")

        # Input-Byte 5 - 6 as int for CPU temperature * 100 (centi degree)
        self.rpi.io.Input_6.replace_io("cputemp", "H")

    def cyclefunction(self, cycletools):
        """This function is called cyclically by RevPiModIODriver."""

        # Timestamp - Write RevPi-Time
        self.rpi.io.timestamp.value = int(time.time())

        # Storage of the root mount
        hd = statvfs("/")
        usedspace = int(
            (hd.f_blocks - hd.f_bavail) / hd.f_blocks * 100
        )
        self.rpi.io.roothdused.value = usedspace

        # CPU-Temperature
        with open("/sys/devices/virtual/thermal/thermal_zone0/temp") as fh:
            tmp = fh.read()
        self.rpi.io.cputemp.value = int(tmp.strip()[:-1])

    def start(self):
        """Start the cycleloop to execute the 'cyclefunction' cyclically."""
        # The program blocks at this point an runs the loop. We set the cycletime
        # to 1000 milliseconds - thats enough for refresh the data.
        self.rpi.cycleloop(self.cyclefunction, cycletime=1000)


if __name__ == "__main__":
    root = MyDriver()
    root.start()
Source code for RevPiModIO Version 1
import revpimodio
import signal
import time
from os import statvfs
from threading import Event


class MyDriver():

    def __init__(self):
        """Instantiates the driver."""
        self._evt_exit = Event()

        # Load configuration
        self._loadconfig()

        # Signal events
        signal.signal(signal.SIGINT, self._sigexit)
        signal.signal(signal.SIGTERM, self._sigexit)
        signal.signal(signal.SIGHUP, self._loadconfig)

    def _loadconfig(self, signum=None, frame=None):
        """Load/Reload configuration."""
        # Instantiate RevPiModIODriver
        self.rpi = revpimodio.RevPiModIODriver([64])

        # Configure RevPiModIODriver

        # Use Input-Byte 0 to 3 as int for timestamp
        self.rpi.devices[64].reg_out("timestamp", "Input_1_i09", "L")

        # Input byte 4 as int use for n% allocation root mount
        self.rpi.devices[64].reg_out("roothdused", "Input_5_i09", "B")

        # Input-Byte 5 - 6 as int for CPU temperature * 100 (centi degree)
        self.rpi.devices[64].reg_out("cputemp", "Input_6_i09", "H")

        # After run() pass These seconds wait until re-run
        self.refresh = 1

    def _sigexit(self, signum, frame):
        """Signal handler to exit."""
        self._evt_exit.set()

    def run(self):
        """Runs until Exit is set."""
        while not self._evt_exit.is_set():

            # Inputs read, from the point of view of logiCAD these are outputs!
            # (even if we're not using them at this moment)
            self.rpi.devices.readprocimg()

            # Timestamp - Write RevPi-Time
            self.rpi.devices[64]["timestamp"].value = int(time.time())

            # Storage of the root mount
            hd = statvfs("/")
            usedspace = int(
                (hd.f_blocks - hd.f_bavail) / hd.f_blocks * 100
            )
            self.rpi.devices[64]["roothdused"].value = usedspace

            # CPU-Temperature
            with open("/sys/devices/virtual/thermal/thermal_zone0/temp") as fh:
                tmp = fh.read()
            self.rpi.devices[64]["cputemp"].value = int(tmp.strip()[:-1])

            # Outputs from the point of view of logiCAD are inputs!
            self.rpi.devices.writeprocimg()

            # Wait
            self._evt_exit.wait(self.refresh)


if __name__ == "__main__":
    root = MyDriver()
    root.run()

 

These data are then available to programs such as logiCAD.

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