import RPi.GPIO as GPIO
import time, math

C = 0.33 # uF
R1 = 1000 # Ohms

GPIO.setmode(GPIO.BCM)

Pin a charges the capacitor through a fixed 1k resistor and the thermistor in series

pin b discharges the capacitor through a fixed 1k resistor

a_pin = 18
b_pin = 23

empty the capacitor ready to start filling it up

def discharge():
GPIO.setup(a_pin, GPIO.IN)
GPIO.setup(b_pin, GPIO.OUT)
GPIO.output(b_pin, False)
time.sleep(0.1)

return the time taken (uS) for the voltage on the capacitor to count as a digital input HIGH

than means around 1.65V

def charge_time():
GPIO.setup(b_pin, GPIO.IN)
GPIO.setup(a_pin, GPIO.OUT)
GPIO.output(a_pin, True)
t1 = time.time()
while not GPIO.input(b_pin):
pass
t2 = time.time()
return (t2 - t1) * 1000000

Take an analog reading as the time taken to charge after first discharging the capacitor

def analog_read():
discharge()
t = charge_time()
discharge()
return t

Convert the time taken to charge the cpacitor into a value of resistance

To reduce errors, do it 100 times and take the average.

def read_resistance():
n = 10
total = 0;
for i in range(1, n):
total = total + analog_read()
t = total / float(n)
T = t * 0.632 * 3.3
r = (T / C) - R1
return r
try:
while True:
print(read_resistance())
time.sleep(0.5)
finally:
GPIO.cleanup()

Sorry if this is not the correct place to post this but can't find another option,

I found the reference on page 78 of how to pull down source code examples from GIT. What I can't find are coding examples such the one for my_server on page 80.

Related, I did not see anywhere to download the referenced myserver.py. I'm Raspbian GNU/Linux 8 (jessie) and Python 2.7.9.

What am I missing?

Thanks