Merge pull request #685 from adafruit/Raspberry_Pi_DS18B20_Temperature_Sensing

Raspberry Pi DS18B20 temperature sensing

Author: ladyada

Raspberry_Pi_DS18B20_Temperature_Sensing/README.md

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+# Raspberry_Pi_DS18B20_Temperature_Sensing
+
+Code to accompany this tutorial:
+https://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing

Raspberry_Pi_DS18B20_Temperature_Sensing/ds18b20-basic-20pin.fzz

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+import glob
+import time
+
+base_dir = '/sys/bus/w1/devices/'
+device_folder = glob.glob(base_dir + '28*')[0]
+device_file = device_folder + '/w1_slave'
+
+def read_temp_raw():
+    f = open(device_file, 'r')
+    lines = f.readlines()
+    f.close()
+    return lines
+
+def read_temp():
+    lines = read_temp_raw()
+    while lines[0].strip()[-3:] != 'YES':
+        time.sleep(0.2)
+        lines = read_temp_raw()
+    equals_pos = lines[1].find('t=')
+    if equals_pos != -1:
+        temp_string = lines[1][equals_pos+2:]
+        temp_c = float(temp_string) / 1000.0
+        temp_f = temp_c * 9.0 / 5.0 + 32.0
+        return temp_c, temp_f
+
+while True:
+    print(read_temp())
+    time.sleep(1)