exclusion lock and note about myself in header, it's not a direct copy.

mcp3008.py

@@ -10,8 +10,11 @@
 Written by Limor Fried, Kevin Townsend and Mikey Sklar for Adafruit Industries. BSD license, all text above must be included in any redistribution
 
 To download, we suggest logging into your Pi with Internet accessibility and typing: git clone https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code.git
+
+Refactored into a class structure and pluggable access objects added by Eric Stein
 """
 import RPi.GPIO as GPIO
+import threading
 
 # change these as desired - they're the pins connected from the
 # SPI port on the ADC to the Cobbler
@@ -63,6 +66,8 @@ def read(self) :
 			return TMP36.c2k(c)
 
 class MCP3008(object) :
+	SPI_LOCK = threading.Lock()
+
 	def __init__(self, mv_aref) :
 		self.mv_aref = mv_aref
 		self.channels = [None] * 8
@@ -74,7 +79,7 @@ def __init__(self, mv_aref) :
 		GPIO.setup(SPICS, GPIO.OUT)
 
 	# read SPI data from MCP3008 chip, 8 possible adc's (0 thru 7)
-	def readadc(self, adcnum, clockpin=SPICLK, mosipin=SPIMOSI, misopin=SPIMISO, cspin=SPICS):
+	def _readadc(self, adcnum, clockpin=SPICLK, mosipin=SPIMOSI, misopin=SPIMISO, cspin=SPICS):
 		if ((adcnum > 7) or (adcnum < 0)):
 		        return -1
 		GPIO.output(cspin, True)
@@ -109,6 +114,13 @@ def readadc(self, adcnum, clockpin=SPICLK, mosipin=SPIMOSI, misopin=SPIMISO, csp
 
 		return adcout * ( self.mv_aref / 1024.0)
 
+	def readadc(self, *args, **kwargs) :
+		self.SPI_LOCK.acquire(True)
+		try :
+			return self._readadc(*args, **kwargs)
+		finally :
+			self.SPI_LOCK.release()
+
 	def setup_channel(self, channel_number, pinobject) :
 		pinobject.setup_mcp3008(self, channel_number)
 		self.channels[channel_number] = pinobject