#!/usr/bin/python
#
# For gstein's 16F688 I2C library, the MCU's I2C address is stored in
# the first byte of EEPROM space.
#
# This script sets that address.
#

import tempfile
import subprocess
import sys
import os


def create_hex(addr):
  fd, path = tempfile.mkstemp(dir='.') #'.hex')

  # Addressing is 32 bits, and this provides the upper 16 bits. The following
  # lines will provide the lower 16 bits.
  os.write(fd, ':020000040000FA\n')

  # Write the I2C address into the first byte of EEPROM space
  checksum = 256 - ((66 + addr) & 0xff)
  os.write(fd, ':02420000%02x00%02x\n' % (addr, checksum))

  # EOF
  os.write(fd, ':00000001FF\n')

  # Done creating the file. We don't really worry about somebody sneaking in,
  # and writing something else. Just return the path.
  os.close(fd)
  return os.path.basename(path)


def set_address(addr):
  path = create_hex(addr)
  subprocess.check_call(['pk2cmd', '-P', 'PIC16F688', '-ME', '-F', path])
  os.remove(path)


if __name__ == '__main__':
  if len(sys.argv) != 2:
    print 'ERROR: %s ADDRESS' % (sys.argv[0],)
    print '   $ %s 20' % (sys.argv[0],)
    print '   $ %s 0x14' % (sys.argv[0],)
    sys.exit(1)

  if sys.argv[1].startswith('0x'):
    addr = int(sys.argv[1], 16)
  else:
    addr = int(sys.argv[1])

  print 'Setting address = 0x%02x' % (addr,)
  set_address(addr)
  print 'Done.'