README

This package offers a Python API to the Oak series of sensors made by Toradex.

Supported Oak devices

The following devices have Python wrappers with the following class names:

• Current sensor: ToradexCurrent
• MagR sensor: ToradexMagR
• Motion sensor: ToradexMotion
• Distance sensor: ToradexDist
• Tilt sensor: ToradexTilt
• Light sensor: ToradexLux
• Accelerometer: ToradexG
• Temperature and humidity sensor: ToradexRH
• Pressure sensor: ToradexP
• 8 channel A2D convertor: Toradex8ChannelA2D

Requirements

pytoradex requires python-hid to be installed. You can get the latest copy here: http://libhid.alioth.debian.org/ or on Ubuntu you can install the package via the command line:

$ sudo apt-get install python-hid 

Installation

To install pytoradex, execute the following on the command line:

$ pip install pytoradex

Opening a Toredex / Oak sensor as a non-root user on Linux

Under Linux based operating systems you may find that, as a normal user, you do not have permissions to open and read from Oak sensors. This means that all your programs will have to be run as sudo or root, which is a security hazard. To fix this, copy the file 59-toradex.rules in the folder /etc/udev/rules.d and restart the udev service by typing the following at the command line:

$ sudo udevadm trigger

Usage

To use one of the sensors wrapped in pytoradex, first create a Python object which corresponds to the sensor you have attached to your USB bus, then open the sensor, then call the relevant get_ method for whatever reading you want to take from the sensor. For example, with an Oak Lux sensor we might want to take an average of one hundred readings:

from pytoradex.toradex import ToradexLux
import time

numreadings = 100
lux = ToradexLux()
try:
    lux.open()
    
    # Turn the LED on to indicate a change of state.
    lux.led_on()
    readings = [lux.get_lux() for i in xrange(numreadings)]
    lux.led_off()
    lux.close()
        
    print 'Average light level: {0}'.format(sum(readings)/numreadings)

except:
    print 'Cannot open Oak Lux sensor. Please check USB cables.'

Every Oak sensor has the following methods which control the red LED at the end of the PCB:

• blink_led
• blink_led_slow
• blink_led_fast
• blink_led_pulse
• led_on
• led_off

If you are debugging your own code you may find it useful to print out all the date coming from the sensor to the command line. You can use our debug utilities to do this:

from pytoradex.toradex import ToradexG

accel = ToradexG()
accel.open()
accel.blink_led()
while True:
    print(accel.debug())

If you have a bunch of Oak sensors connected to the USB bus, rather than creating a Python object for each one, you can use the ToradexSensorCollection class to open several devices at once:

import time
from pytoradex.toradex import ToradexSensorCollection

collection = ToradexSensorCollection()
print(collection.open())
while True:
    collection.debug() # Will print output of each sensor in turn.
    time.sleep(1)

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© Sarah Mount, University of Wolverhampton, 2010.