scripts/i2c.py

   1 #!/usr/bin/env python
   2 # -*- coding: iso-8859-15 -*-
   3
   4 import threading
   5 import inspect
   6 import os
   7 import logging
   8 import struct
   9 from ctypes import *
  10 from time import sleep
  11
  12 DEBUG=0
  13 logger = logging.getLogger(__name__)
  14
  15 class i2c:
  16         libc = CDLL("libc.so.6")
  17         I2C_SLAVE = 0x0703  # Use this slave address
  18         __single = None
  19         __lock = threading.Lock()
  20         __parent_owner = None
  21
  22         def __init__(self, addr):
  23                 with i2c.__lock:
  24                         count = 0
  25                         while(i2c.__single):
  26                                 parent = inspect.stack()[1][3]
  27                                 count += 1
  28                                 sleep(0.001)
  29                         if DEBUG:
  30                                 if count > 10:
  31                                         parent_owner = "%s (%d), %s()" % (self.__parent_owner[1], self.__parent_owner[2], self.__parent_owner[3])
  32                                         logger.warning("Error: (%s) I2C blocked %fs by %s!", parent, count*0.001, parent_owner)
  33                                 i2c.__parent_owner = inspect.stack()[1]
  34                         i2c.__single = True
  35                 self.dev = i2c.libc.open("/dev/i2c-2", os.O_RDWR)
  36                 if self.dev < 0:
  37                         raise IOError("open")
  38                 err = i2c.libc.ioctl(self.dev, i2c.I2C_SLAVE, addr>>1)
  39                 if err < 0:
  40                         raise IOError("ioctl")
  41
  42         def write(self, s):
  43                 num_write = i2c.libc.write(self.dev, s, len(s))
  44                 if num_write != len(s):
  45                         self.close()
  46                         raise IOError("write: %d" % (num_write))
  47
  48         def read(self, num):
  49                 buf = create_string_buffer(num)
  50                 num_read = i2c.libc.read(self.dev, buf, num)
  51                 if num_read != num:
  52                         self.close()
  53                         raise IOError("read: %d" % (num_read))
  54                 return buf.raw
  55
  56         def close(self):
  57                 if self.dev:
  58                         i2c.libc.close(self.dev)
  59                         self.dev = None
  60                         #i2c.__parent_owner = None
  61                         i2c.__single = None
  62
  63         def __del__(self):
  64                 self.close()
  65
  66
  67 def i2c_write_reg(addr, reg, buf):
  68         dev = i2c(addr)
  69         s = struct.pack(">B", reg) + buf
  70         dev.write(s)
  71         dev.close()
  72
  73
  74 def i2c_read_reg(addr, reg, num=1):
  75         dev = i2c(addr)
  76         s = struct.pack(">B", reg)
  77         dev.write(s)
  78         s = dev.read(num)
  79         dev.close()
  80         return s
  81
  82
  83 if __name__ == "__main__":
  84         import struct
  85         import sys
  86
  87         dev = i2c(0x50)
  88         s = struct.pack(">Bh", int(sys.argv[1]), int(sys.argv[2]))
  89         dev.write(s)
  90         dev.close()