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This driver supports, and was tested with, a DS18B20 1-wire Temperature Sensor using external power. This device requires the use of a UART to provide access to a Dallas 1-wire bus, via a new facility supported by MRAA (once the relevant PR is accepted), using the UartOW access class. It is important to realize that the UART is only being used to access and control a Dallas 1-wire compliant bus, it is not actually a UART device. Multiple DS18B20 devices can be connected to this bus. This module will identify all such devices connected, and allow you to access them using an index starting at 0. Parasitic power is not currently supported due to the very tight 10us limit on switching a GPIO properly to supply power during certain operations. For this reason, you should use external power for your sensors. Setting the alarm values (Tl, Th) is also not supported, since this is only useful when doing a 1-wire device search looking for devices in an alarm state, a capability not yet supported in MRAA. In reality, this is trivial to handle yourself in your application. Signed-off-by: Jon Trulson <jtrulson@ics.com> Signed-off-by: Noel Eck <noel.eck@intel.com>
65 lines
2.1 KiB
Python
65 lines
2.1 KiB
Python
#!/usr/bin/python
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# Author: Jon Trulson <jtrulson@ics.com>
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# Copyright (c) 2016 Intel Corporation.
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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import time, sys, signal, atexit
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import pyupm_ds18b20 as sensorObj
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## Exit handlers ##
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# This function stops python from printing a stacktrace when you hit control-C
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def SIGINTHandler(signum, frame):
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raise SystemExit
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# This function lets you run code on exit
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def exitHandler():
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print "Exiting..."
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sys.exit(0)
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# Register exit handlers
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atexit.register(exitHandler)
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signal.signal(signal.SIGINT, SIGINTHandler)
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print "Initializing..."
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# Instantiate an DS18B20 instance using the default values (uart 0)
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sensor = sensorObj.DS18B20(0)
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# locate and setup our devices
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sensor.init()
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print "Found", sensor.devicesFound(), "device(s)"
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print
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if (not sensor.devicesFound()):
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sys.exit(1);
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# update and print available values every second
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while (1):
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# update our values for the first sensor
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sensor.update(0)
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# we show both C and F for temperature for the first sensor
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print "Temperature:", sensor.getTemperature(0), "C /",
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print sensor.getTemperature(0, True), "F"
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time.sleep(1)
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