/
Adafruit_I2C.py
executable file
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Adafruit_I2C.py
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#!/usr/bin/python
import smbus
# ===========================================================================
# Adafruit_I2C Base Class
# ===========================================================================
class Adafruit_I2C :
def getPiRevision():
"Gets the version number of the Raspberry Pi board"
# Courtesy quick2wire-python-api
# https://github.com/quick2wire/quick2wire-python-api
try:
with open('/proc/cpuinfo','r') as f:
for line in f:
if line.startswith('Revision'):
return 1 if line.rstrip()[-1] in ['1','2'] else 2
except:
return 0
def __init__(self, address, bus=smbus.SMBus(1 if getPiRevision() > 1 else 0), debug=False):
self.address = address
# By default, the correct I2C bus is auto-detected using /proc/cpuinfo
self.bus = bus
# Alternatively, you can hard-code the bus version below:
# self.bus = smbus.SMBus(0); # Force I2C0 (early 256MB Pi's)
# self.bus = smbus.SMBus(1); # Force I2C1 (512MB Pi's)
self.debug = debug
def reverseByteOrder(self, data):
"Reverses the byte order of an int (16-bit) or long (32-bit) value"
# Courtesy Vishal Sapre
dstr = hex(data)[2:].replace('L','')
byteCount = len(dstr[::2])
val = 0
for i, n in enumerate(range(byteCount)):
d = data & 0xFF
val |= (d << (8 * (byteCount - i - 1)))
data >>= 8
return val
def write8(self, reg, value):
"Writes an 8-bit value to the specified register/address"
try:
self.bus.write_byte_data(self.address, reg, value)
if (self.debug):
print "I2C: Wrote 0x%02X to register 0x%02X" % (value, reg)
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1
def writeList(self, reg, list):
"Writes an array of bytes using I2C format"
try:
if (self.debug):
print "I2C: Writing list to register 0x%02X:" % reg
print list
self.bus.write_i2c_block_data(self.address, reg, list)
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1
def readList(self, reg, length):
"Read a list of bytes from the I2C device"
results = []
try:
results = self.bus.read_i2c_block_data(self.address, reg, length)
if (self.debug):
print "I2C: Device 0x%02X returned the following from reg 0x%02X" % (self.address, reg)
print results
return results
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1
def readU8(self, reg):
"Read an unsigned byte from the I2C device"
try:
result = self.bus.read_byte_data(self.address, reg)
if (self.debug):
print "I2C: Device 0x%02X returned 0x%02X from reg 0x%02X" % (self.address, result & 0xFF, reg)
return result
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1
def readS8(self, reg):
"Reads a signed byte from the I2C device"
try:
result = self.bus.read_byte_data(self.address, reg)
if (self.debug):
print "I2C: Device 0x%02X returned 0x%02X from reg 0x%02X" % (self.address, result & 0xFF, reg)
if (result > 127):
return result - 256
else:
return result
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1
def readU16(self, reg):
"Reads an unsigned 16-bit value from the I2C device"
try:
hibyte = self.bus.read_byte_data(self.address, reg)
result = (hibyte << 8) + self.bus.read_byte_data(self.address, reg+1)
if (self.debug):
print "I2C: Device 0x%02X returned 0x%04X from reg 0x%02X" % (self.address, result & 0xFFFF, reg)
return result
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1
def readS16(self, reg):
"Reads a signed 16-bit value from the I2C device"
try:
hibyte = self.bus.read_byte_data(self.address, reg)
if (hibyte > 127):
hibyte -= 256
result = (hibyte << 8) + self.bus.read_byte_data(self.address, reg+1)
if (self.debug):
print "I2C: Device 0x%02X returned 0x%04X from reg 0x%02X" % (self.address, result & 0xFFFF, reg)
return result
except IOError, err:
print "Error accessing 0x%02X: Check your I2C address" % self.address
return -1