Port of the TMP006 example code to python, some fixes for 16bit SPI access from python

Adafruit_BMP085/Adafruit_BMP085_example.py

@@ -1,7 +1,20 @@
 #!/usr/bin/python
 
+from time import sleep
 from Adafruit_BMP085 import BMP085
 
+def C_to_F(C):
+  return C * (180.0 / 100.0) + 32.0
+
+def m_to_ft(m):
+  return 3.2808399 * m
+
+def hPa_to_inHg(hPa):
+  return hPa / 33.86389
+
+def hPa_to_psi(hPa):
+  return hPa / 0.0145037
+
 # ===========================================================================
 # Example Code
 # ===========================================================================
@@ -16,10 +29,12 @@
 # bmp = BMP085(0x77, 2)  # HIRES Mode
 # bmp = BMP085(0x77, 3)  # ULTRAHIRES Mode
 
-temp = bmp.readTemperature()
-pressure = bmp.readPressure()
-altitude = bmp.readAltitude()
+while True:
+  temp = bmp.readTemperature()
+  pressure = bmp.readPressure()
+  altitude = bmp.readAltitude()
 
-print "Temperature: %.2f C" % temp
-print "Pressure:    %.2f hPa" % (pressure / 100.0)
-print "Altitude:    %.2f" % altitude
+  print "Temperature: %.2f C / %.2f F" % (temp, C_to_F(temp))
+  print "Pressure:    %.2f hPa / %.2f inHg" % ((pressure / 100.0), hPa_to_inHg(pressure / 100.0))
+  print "Altitude:    %.2f m / %.1f ft" % (altitude, m_to_ft(altitude))
+  sleep(2.0)

Adafruit_I2C/Adafruit_I2C.py

@@ -1,6 +1,7 @@
 #!/usr/bin/python
 
 import smbus
+from ctypes import c_short
 
 # ===========================================================================
 # Adafruit_I2C Class
@@ -61,11 +62,11 @@ def write8(self, reg, value):
 
   def write16(self, reg, value):
     "Writes a 16-bit value to the specified register/address pair"
+    value = ((value << 8) & 0xff00) | ((value >> 8) & 0xff)
     try:
       self.bus.write_word_data(self.address, reg, value)
       if self.debug:
-        print ("I2C: Wrote 0x%02X to register pair 0x%02X,0x%02X" %
-         (value, reg, reg+1))
+        print ("I2C: Wrote 0x%04X to register 0x%02X" % (value, reg))
     except IOError, err:
       return self.errMsg()
 
@@ -117,9 +118,10 @@ def readS8(self, reg):
   def readU16(self, reg):
     "Reads an unsigned 16-bit value from the I2C device"
     try:
-      hibyte = self.readU8(reg)
-      lobyte = self.readU8(reg+1)
-      result = (hibyte << 8) + lobyte
+      result = self.bus.read_word_data(self.address, reg)
+      hibyte = 0xff & result
+      lobyte = 0xff & (result >> 8)
+      result = (hibyte << 8) | lobyte
       if (self.debug):
         print "I2C: Device 0x%02X returned 0x%04X from reg 0x%02X" % (self.address, result & 0xFFFF, reg)
       return result
@@ -129,9 +131,13 @@ def readU16(self, reg):
   def readS16(self, reg):
     "Reads a signed 16-bit value from the I2C device"
     try:
-      hibyte = self.readS8(reg)
-      lobyte = self.readU8(reg+1)
-      result = (hibyte << 8) + lobyte
+      #hibyte = self.readS8(reg)
+      #lobyte = self.readU8(reg+1)
+      #result = (hibyte << 8) + lobyte
+      result = self.bus.read_word_data(self.address, reg)
+      hibyte = 0xff & result
+      lobyte = 0xff & (result >> 8)
+      result = c_short((hibyte << 8) + lobyte).value
       if (self.debug):
         print "I2C: Device 0x%02X returned 0x%04X from reg 0x%02X" % (self.address, result & 0xFFFF, reg)
       return result

Adafruit_TMP006/Adafruit_I2C.py

@@ -0,0 +1 @@
+../Adafruit_I2C/Adafruit_I2C.py

Adafruit_TMP006/Adafruit_TMP006.py

@@ -0,0 +1,134 @@
+#!/usr/bin/python
+
+import time
+from Adafruit_I2C import Adafruit_I2C
+from math import sqrt
+
+# ===========================================================================
+# TMP006 Class
+# ===========================================================================
+
+class TMP006 :
+  i2c = None
+
+  # TMP006 Registers
+  __TMP006_REG_VOBJ   = 0x00
+  __TMP006_REG_TAMB   = 0x01
+  __TMP006_REG_CONFIG = 0x02
+  __TMP006_REG_MANID  = 0xFE
+  __TMP006_REG_DEVID  = 0xFF
+
+  # CONFIG Register Values
+  __TMP006_CFG_RESET    = 0x8000
+  __TMP006_CFG_MODEON   = 0x7000
+  __TMP006_CFG_1SAMPLE  = 0x0000
+  __TMP006_CFG_2SAMPLE  = 0x0200
+  __TMP006_CFG_4SAMPLE  = 0x0400
+  __TMP006_CFG_8SAMPLE  = 0x0600
+  __TMP006_CFG_16SAMPLE = 0x0800
+  __TMP006_CFG_DRDYEN   = 0x0100
+  __TMP006_CFG_DRDY     = 0x0080
+
+  # Manufacturer ID
+  __TMP006_MANID = 0x5449
+
+  # Device ID
+  __TMP006_DEVID = 0x0067
+
+  # Internal Data
+  __TMP006_B0 = -0.0000294
+  __TMP006_B1 = -0.00000057
+  __TMP006_B2 = 0.00000000463
+  __TMP006_C2 = 13.4
+  __TMP006_TREF = 298.15
+  __TMP006_A2 = -0.00001678
+  __TMP006_A1 = 0.00175
+  __TMP006_S0 = 6.4  # * 10^-14
+
+  # Constructor
+  def __init__(self, address=0x40, mode=1, debug=False):
+    self.i2c = Adafruit_I2C(address)
+
+    self.address = address
+    self.debug = debug
+    self.started = False
+
+  # Destructor
+  def __del__(self):
+    if self.started:
+      self.i2c.write16(self.__TMP006_REG_CONFIG, 0);
+
+  # Start Sampling
+  def begin(self, samplerate=__TMP006_CFG_16SAMPLE):
+    self.i2c.write16(self.__TMP006_REG_CONFIG,
+                     self.__TMP006_CFG_MODEON | self.__TMP006_CFG_DRDYEN | samplerate);
+
+    self.started = True
+
+    mid = self.i2c.readU16(self.__TMP006_REG_MANID)
+    did = self.i2c.readU16(self.__TMP006_REG_DEVID)
+
+    if self.debug:
+      print "mid = 0x%x" % mid
+      print "did = 0x%x" % did
+
+    if mid != self.__TMP006_MANID:
+      print "WARN TMP006: Manufacturer ID Mismatch (%04X)" % mid
+    if did != self.__TMP006_DEVID:
+      print "WARN TMP006: Device ID Mismatch (%04X)" % did
+
+  def readRawDieTemperature(self):
+    "Read the raw die temperature"
+    raw = self.i2c.readS16(self.__TMP006_REG_TAMB)
+    raw >>= 2
+    if self.debug:
+      C = raw * 0.03125
+      print "Raw Tambient: 0x%04X (%f C)" % (raw, C)
+    return raw
+
+  def readRawVoltage(self):
+    "Read the raw voltage"
+    raw = self.i2c.readS16(self.__TMP006_REG_VOBJ)
+    if self.debug:
+      v = raw
+      v *= 156.25
+      v /= 1000
+      print "Raw voltage: 0x%04X (%f uV)" % (raw, v)
+    return raw
+
+  def readDieTempC(self):
+   Tdie = self.readRawDieTemperature()
+   Tdie *= 0.03125 # convert to celsius
+   if self.debug:
+     print "Tdie = ", Tdie
+   return Tdie
+
+  def readObjTempC(self):
+    Tdie = self.readRawDieTemperature()
+    Vobj = self.readRawVoltage()
+    Vobj *= 156.25  # 156.25 nV per LSB
+    Vobj /= 1000    # nV -> uV
+    Vobj /= 1000    # uV -> mV
+    Vobj /= 1000    # mV -> V
+    Tdie *= 0.03125 # convert to celsius
+    Tdie += 273.15  # convert to kelvin
+
+    if self.debug:
+      print "Vobj = ", Vobj * 1000000, "uV"
+      print "Tdie = ", Tdie, " C"
+
+    tdie_tref = Tdie - self.__TMP006_TREF
+    S = 1 + self.__TMP006_A1 * tdie_tref \
+        + self.__TMP006_A2 * tdie_tref * tdie_tref
+    S *= self.__TMP006_S0
+    S /= 10000000
+    S /= 10000000
+
+    Vos = self.__TMP006_B0 + self.__TMP006_B1 * tdie_tref \
+        + self.__TMP006_B2 * tdie_tref * tdie_tref
+
+    fVobj = (Vobj - Vos) + self.__TMP006_C2 * (Vobj-Vos)*(Vobj-Vos)
+    Tobj = sqrt(sqrt(Tdie * Tdie * Tdie * Tdie + fVobj/S))
+
+    Tobj -= 273.15 # Kelvin -> *C
+    return Tobj

Adafruit_TMP006/Adafruit_TMP006_example.py

@@ -0,0 +1,30 @@
+#!/usr/bin/python
+
+from Adafruit_TMP006 import TMP006
+from time import sleep
+
+def C_to_F(C):
+  return C * (180.0 / 100.0) + 32.0
+
+# ===========================================================================
+# Example Code
+# ===========================================================================
+
+# Initialise the TMP006 and use defaults
+# tmp = TMP006(0x40, debug=True)
+tmp = TMP006(0x41)
+
+# Start sampling
+tmp.begin()
+
+# Wait a short bit for sample averaging
+while True:
+  print "Pausing 2.0 s..."
+  sleep(2.0)
+
+  dietemp = tmp.readDieTempC()
+  objtemp = tmp.readObjTempC()
+
+  print "Die Temperature:    %.2f C / %.2f F" % (dietemp, C_to_F(dietemp))
+  print "Object Temperature: %.2f C / %.2f F" % (objtemp, C_to_F(objtemp))
+