py-opc
Python library for operating the Alphasense OPC-N2 Optical Particle Counter using a Raspberry Pi (or other linux device). Full documentation can be found here.
Dependencies
One of the following, depending on whether you use GPIO pins or a SPI-USB adapter:
Additional Dependencies for Local Development
If you wish to build the local documentation or run unittests, there are a few additional dependencies that are required including:
- sphinx
- sphinx_rtd_theme
- mock
The complete list can be found in requirements-dev.txt
.
Installation
For use on the Raspberry Pi (or any other linux device?), install via pip:
$ pip install py-opc [--upgrade]
As pyusbiss
is not yet available through a package manager, you must download from source (if you are using the SPI-USB adapter only). This can be done as follows:
$ pip install git+https://github.com/DancingQuanta/pyusbiss.git
If you are using the GPIO pins to communicate with the OPC-N2, you must download the requirement py-spidev
as follows:
$ pip install git+https://github.com/doceme/py-spidev.git
License
This library is licensed under the MIT license. The full text of the license can be found in this repository at LICENSE.txt.
Documentation
Full documentation can be found here.
You can also build the documentation by navigating to the docs
directory and issuing the command:
$ make html
Sample Script / Getting Started
To quickly get up and running, follow one of the two examples:
GPIO-connected OPC-N2
Use if you are using the GPIO pins in conjunction with py-spidev
import spidev
import opc
from time import sleep
spi = spidev.SpiDev()
spi.open(0, 0)
spi.mode = 1
spi.max_speed_hz = 500000
alphasense = opc.OPCN2(spi)
# Turn the opc ON
alphasense.on()
sleep(1)
# Read the information string
print (alphasense.read_info_string())
# Read the histogram
print (alphasense.histogram())
# Turn the opc OFF
alphasense.off()
SPI-USB Adapter with OPC-N2
Use this approach if you have connected your RPi to the OPC-N2 via a SPI-USB adapter.
NOTE: Currently, this method is only supported on python3+ due to limitations in the pyusbiss
library.
from usbiss.spi import SPI
import opc
from time import sleep
# Build the connector
spi = SPI("/dev/ttyACM0")
# Set the SPI mode and clock speed
spi.mode = 1
spi.max_speed_hz = 500000
alpha = opc.OPCN2(spi)
# Turn on the device
alpha.on()
sleep(1)
# read the information string
print (repr(alpha.read_info_string()))
# Read the histogram
alpha.histogram()
# Turn the device off
alpha.off()