Initialize piNail project with modern piNail2 web controller

MAX6675-master/MAX6675/MAX6675.py

@@ -0,0 +1,78 @@
+# Copyright (c) 2015 Troy Dack
+# Author: Troy Dack
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+import logging
+
+import Adafruit_GPIO as GPIO
+import Adafruit_GPIO.SPI as SPI
+
+class MAX6675(object):
+	"""Class to represent a MAX6675 thermocouple temperature measurement board.
+	"""
+
+	def __init__(self, clk=None, cs=None, do=None, spi=None, gpio=None):
+		"""Initialize MAX6675 device with software SPI on the specified CLK,
+		CS, and DO pins.  Alternatively can specify hardware SPI by sending an
+		Adafruit_GPIO.SPI.SpiDev device in the spi parameter.
+		"""
+		self._logger = logging.getLogger('MAX6675.MAX6675')
+		self._spi = None
+		# Handle hardware SPI
+		if spi is not None:
+			self._logger.debug('Using hardware SPI')
+			self._spi = spi
+		elif clk is not None and cs is not None and do is not None:
+			self._logger.debug('Using software SPI')
+			# Default to platform GPIO if not provided.
+			if gpio is None:
+				gpio = GPIO.get_platform_gpio()
+			self._spi = SPI.BitBang(gpio, clk, None, do, cs)
+		else:
+			raise ValueError('Must specify either spi for for hardware SPI or clk, cs, and do for softwrare SPI!')
+		self._spi.set_clock_hz(5000000)
+		self._spi.set_mode(0)
+		self._spi.set_bit_order(SPI.MSBFIRST)
+
+	def readTempC(self):
+		"""Return the thermocouple temperature value in degrees celsius."""
+		v = self._read16()
+		# Check for error reading value.
+		if v & 0x4:
+			return float('NaN')
+		# Check if signed bit is set.
+		if v & 0x80000000:
+			# Negative value, take 2's compliment. Compute this with subtraction
+			# because python is a little odd about handling signed/unsigned.
+			v >>= 3 # only need the 12 MSB
+			v -= 4096
+		else:
+			# Positive value, just shift the bits to get the value.
+			v >>= 3 # only need the 12 MSB
+		# Scale by 0.25 degrees C per bit and return value.
+		return v * 0.25
+
+	def _read16(self):
+		# Read 16 bits from the SPI bus.
+		raw = self._spi.read(2)
+		if raw is None or len(raw) != 2:
+			raise RuntimeError('Did not read expected number of bytes from device!')
+		value = raw[0] << 8 | raw[1]
+		self._logger.debug('Raw value: 0x{0:08X}'.format(value & 0xFFFFFFFF))
+		return value