Writing out data

Data contained in IntelHex can be written out in a few different formats, including HEX, bin, or python dictionaries.

You can write out HEX data contained in object by method .write_hex_file(f). Parameter f should be filename or file-like object. Note that this can include builtins like sys.stdout. Also you can use the universal tofile.

To convert data of IntelHex object to HEX8 file format without actually saving it to disk you can use the builtin StringIO file-like object, e.g.:

>>> from cStringIO import StringIO
>>> from intelhex import IntelHex
>>> ih = IntelHex()
>>> ih[0] = 0x55
>>> sio = StringIO()
>>> ih.write_hex_file(sio)
>>> hexstr = sio.getvalue()
>>> sio.close()

Variable hexstr will contain a string with the content of a HEX8 file.

You can customize hex file output with following optional arguments to write_hex_file call:

  • write_start_addr - you can disable start address record in new hex file;
  • eolstyle - you can force CRLF line endings in new hex file.
  • byte_count - you can control how many bytes should be written to each data record.

Data converters

To write data as a hex file with default settings you also can use universal method tofile:

# the code below is the same as "ih.write_hex_file(sio)"
>>> ih.tofile(sio, format='hex')

Class IntelHex has several methods for converting data of IntelHex objects into binary form:

  • tobinarray (returns array of unsigned char bytes);
  • tobinstr (returns string of bytes);
  • tobinfile (convert content to binary form and write to file).


>>> from intelhex import IntelHex
>>> ih = IntelHex("foo.hex")
>>> ih.tobinfile("foo.bin")

Also you can use universal method tofile to write data as binary file:

>>> ih.tofile("foo.bin", format='bin')

Writing data in chunks

If you need to get binary data from IntelHex as series of chunks then you can pass to tobinarray/tobinstr methods either start/end addresses or start address and required size of the chunk. This could be useful if you’re creating Eeprom/Flash IC programmer or bootloader.

EEPROM_SIZE = 8192  # 8K bytes
BLOCK_SIZE = 128    # 128 bytes
for addr in range(0, EEPROM_SIZE, BLOCK_SIZE):
    eeprom.i2c_write(addr, ih.tobinarray(start=addr, size=BLOCK_SIZE))