142 lines
4.5 KiB
Python
Executable file
142 lines
4.5 KiB
Python
Executable file
#!/usr/bin/python
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import smbus
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# ===========================================================================
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# Adafruit_I2C Class
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# ===========================================================================
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class Adafruit_I2C :
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@staticmethod
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def getPiRevision():
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"Gets the version number of the Raspberry Pi board"
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# Courtesy quick2wire-python-api
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# https://github.com/quick2wire/quick2wire-python-api
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try:
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with open('/proc/cpuinfo','r') as f:
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for line in f:
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if line.startswith('Revision'):
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return 1 if line.rstrip()[-1] in ['1','2'] else 2
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except:
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return 0
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@staticmethod
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def getPiI2CBusNumber():
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# Gets the I2C bus number /dev/i2c#
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return 1 if Adafruit_I2C.getPiRevision() > 1 else 0
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def __init__(self, address, busnum=-1, debug=False):
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self.address = address
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# By default, the correct I2C bus is auto-detected using /proc/cpuinfo
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# Alternatively, you can hard-code the bus version below:
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# self.bus = smbus.SMBus(0); # Force I2C0 (early 256MB Pi's)
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# self.bus = smbus.SMBus(1); # Force I2C1 (512MB Pi's)
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self.bus = smbus.SMBus(
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busnum if busnum >= 0 else Adafruit_I2C.getPiI2CBusNumber())
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self.debug = debug
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def reverseByteOrder(self, data):
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"Reverses the byte order of an int (16-bit) or long (32-bit) value"
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# Courtesy Vishal Sapre
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byteCount = len(hex(data)[2:].replace('L','')[::2])
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val = 0
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for i in range(byteCount):
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val = (val << 8) | (data & 0xff)
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data >>= 8
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return val
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def errMsg(self):
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print "Error accessing 0x%02X: Check your I2C address" % self.address
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return -1
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def write8(self, reg, value):
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"Writes an 8-bit value to the specified register/address"
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try:
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self.bus.write_byte_data(self.address, reg, value)
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if self.debug:
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print "I2C: Wrote 0x%02X to register 0x%02X" % (value, reg)
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except IOError, err:
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return self.errMsg()
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def write16(self, reg, value):
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"Writes a 16-bit value to the specified register/address pair"
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try:
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self.bus.write_word_data(self.address, reg, value)
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if self.debug:
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print ("I2C: Wrote 0x%02X to register pair 0x%02X,0x%02X" %
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(value, reg, reg+1))
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except IOError, err:
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return self.errMsg()
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def writeList(self, reg, list):
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"Writes an array of bytes using I2C format"
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try:
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if self.debug:
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print "I2C: Writing list to register 0x%02X:" % reg
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print list
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self.bus.write_i2c_block_data(self.address, reg, list)
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except IOError, err:
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return self.errMsg()
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def readList(self, reg, length):
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"Read a list of bytes from the I2C device"
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try:
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results = self.bus.read_i2c_block_data(self.address, reg, length)
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if self.debug:
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print ("I2C: Device 0x%02X returned the following from reg 0x%02X" %
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(self.address, reg))
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print results
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return results
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except IOError, err:
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return self.errMsg()
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def readU8(self, reg):
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"Read an unsigned byte from the I2C device"
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try:
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result = self.bus.read_byte_data(self.address, reg)
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if self.debug:
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print ("I2C: Device 0x%02X returned 0x%02X from reg 0x%02X" %
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(self.address, result & 0xFF, reg))
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return result
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except IOError, err:
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return self.errMsg()
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def readS8(self, reg):
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"Reads a signed byte from the I2C device"
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try:
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result = self.bus.read_byte_data(self.address, reg)
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if result > 127: result -= 256
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if self.debug:
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print ("I2C: Device 0x%02X returned 0x%02X from reg 0x%02X" %
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(self.address, result & 0xFF, reg))
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return result
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except IOError, err:
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return self.errMsg()
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def readU16(self, reg):
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"Reads an unsigned 16-bit value from the I2C device"
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try:
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result = self.bus.read_word_data(self.address,reg)
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if (self.debug):
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print "I2C: Device 0x%02X returned 0x%04X from reg 0x%02X" % (self.address, result & 0xFFFF, reg)
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return result
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except IOError, err:
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return self.errMsg()
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def readS16(self, reg):
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"Reads a signed 16-bit value from the I2C device"
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try:
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result = self.bus.read_word_data(self.address,reg)
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if (self.debug):
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print "I2C: Device 0x%02X returned 0x%04X from reg 0x%02X" % (self.address, result & 0xFFFF, reg)
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return result
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except IOError, err:
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return self.errMsg()
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if __name__ == '__main__':
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try:
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bus = Adafruit_I2C(address=0)
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print "Default I2C bus is accessible"
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except:
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print "Error accessing default I2C bus"
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