1.1   About

The Intel HEX file format widely used in microprocessors and microcontrollers area as the de-facto standard for representation of code for programming microelectronic devices.

This work implements an intelhex Python library to read, write, create from scratch and manipulate data from HEX (also known as Intel HEX) file format. These operations are provided by IntelHex class.

The distribution package also includes several convenience Python scripts to do basic tasks that utilize this library. The bin2hex.py script converts binary data to HEX, and the hex2bin.py works the other direction. hex2dump.py converts data from HEX to a hexdump which is useful for inspecting data, and hexmerge.py merges multiple HEX files into one.

This manual and more information can be found at:

http://www.bialix.com/intelhex/

or at the Launchpad.net project page at:

https://launchpad.net/intelhex/

1.2   License

The code distributed under the BSD license. See LICENSE.txt in sources archive.

1.3   Installation

IntelHex may be downloaded from:

https://launchpad.net/intelhex/+download

or

http://www.bialix.com/intelhex/

IntelHex is distributed as a standard Python Distutils package. Assuming Python is properly installed on your platform, installation should just require running the following command from the root directory of the archive:

sudo python setup.py install

This will install the intelhex package into your system's site-packages directory and place the helper scripts in your Python site-packages binaries directory. After that is done, any other Python scripts or modules should be able to import the package using:

>>> from intelhex import IntelHex

The scripts should be in your PATH so that they can be called from anywhere in the file system.

See the Python distutils website for more information, or try typing, python setup.py --help from the root directory of the archive.

2.1   Initializing the class

Example of typical initialization of IntelHex class:

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

In the second line we are creating an instance of the class. The constructor optionally takes data to initialize the class. This can be the name of the HEX file, a file-like object, a dictionary, or another instance of IntelHex. If specified, this source is automatically read and decoded. Because of the flexibility of file-like objects in Python, objects like sys.stdin can be used.

If the source is another instance of IntelHex, the new object will become a copy of the source. Finally, a Python dictionary may be specified. This dictionary should have keys equal to memory locations and values equal to the data stored in those locations. See the docstrings for more details.

In version 0.9 the API slightly changed. Now you can create an empty object and load data later.

2.2   Reading data

Once created, an IntelHex object can be loaded with data. This is only necessary if "source" was unspecified in the constructor. You can also load data several times (but if addresses in those files overlap you get exception AddressOverlapError). This error is only raised when reading from hex files. When reading from other formats, without explicitly calling merge, the data will be overwritten. E.g.:

>>> from intelhex import IntelHex
>>> ih = IntelHex()                     # create empty object
>>> ih.loadhex('foo.hex')               # load from hex
>>> ih.loadfile('bar.hex',format='hex') # also load from hex
>>> ih.fromfile('bar.hex',format='hex') # also load from hex

NOTE: using IntelHex.fromfile is recommended way.

All of the above examples will read from HEX files. IntelHex also supports reading straight binary files. For example:

>>> from intelhex import IntelHex
>>> ih = IntelHex()                     # create empty object
>>> ih.loadbin('foo.bin')               # load from bin
>>> ih.fromfile('bar.bin',format='bin') # also load from bin

Finally, data can be loaded from an appropriate Python dictionary. This will permit you to store the data in an IntelHex object to a builtin dictionary and restore the object at a later time. For example:

>>> from intelhex import IntelHex
>>> ih = IntelHex('foo.hex') # create empty object
>>> pydict = ih.todict()     # dump contents to pydict

...do something with the dictionary...

>>> newIH = IntelHex(pydict) # recreate object with dict
>>> another = IntelHex()     # make a blank instance
>>> another.fromdict(pydict) # now another is the same as newIH

2.3   Basic data inspection

You can get or modify some data by address in the usual way: via Python indexing operations:

>>> print ih[0] # read data from address 0

When you need to work with 16-bit data stored in 8-bit Intel HEX files you need to use class IntelHex16bit. This class is derived from IntelHex and has all its methods. Some of methods have been modified to implement 16-bit behaviour.

This class assumes the data is in Little Endian byte order. The data can be accessed exactly like above, except that data returned will be 16 bits, and the addresses should be word addresses.

Another useful inspection tool is the dump command. This will output the entire contents of the hex file to stdout or to a specified file object like so:

>>> ih.dump() # dump contents of ih to stdout in tabular hexdump format

>>> f = open('hexdump.txt', 'w') # open file for writing
>>> ih.dump(f)                   # dump to file object
>>> f.close()                    # close file

2.4   More data inspection

IntelHex provides some metadata about the hex file it contains. To obtain address limits use methods .minaddr() and .maxaddr(). These are computed based on the lowest and highest used memory spaces respectively.

Some linkers write to produced HEX file information about start address (either record 03 or 05). IntelHex is able correctly read such records and store information internally in start_addr attribute that itself is either None or a dictionary with the address value(s).

When input HEX file contains record type 03 (Start Segment Address Record), start_addr takes value:

{'CS': XXX, 'IP': YYY}

Here:

• XXX is value of CS register
• YYY is value of IP register

To obtain or change CS or IP value you need to use their names as keys for start_addr dictionary:

>>> ih = IntelHex('file_with_03.hex')
>>> print ih.start_addr['CS']
>>> print ih.start_addr['IP']

When input HEX file contains record type 05 (Start Linear Address Record), start_addr takes value:

{'EIP': ZZZ}

Here ZZZ is value of EIP register.

Example:

>>> ih = IntelHex('file_with_05.hex')
>>> print ih.start_addr['EIP']

You can manually set required start address:

>>> ih.start_addr = {'CS': 0x1234, 'IP': 0x5678}
>>> ih.start_addr = {'EIP': 0x12345678}

To delete start address info give value None or empty dictionary:

>>> ih.start_addr = None
>>> ih.start_addr = {}

When you write data to HEX file you can disable writing start address with additional argument write_start_addr:

>>> ih.write_hex_file('out.hex') # by default writing start address
>>> ih.write_hex_file('out.hex', True) # as above
>>> ih.write_hex_file('out.hex', False) # don't write start address

When start_addr is None or an empty dictionary nothing will be written regardless of write_start_addr argument value.

For more information about start address, please see the Intel Hex file format specification.

Because Intel Hex files do not specify every location in memory, it is necessary to have a padding byte defined. Whenever a read is attempted from an address that is unspecified, the padding byte is returned. This default data is set via attribute .padding of class instance. This defaults to '0xFF', but it can be changed by the user like so:

>>> print ih[0]       # prints 0xFF because this location is blank
>>> ih.padding = 0x00 # change padding byte
>>> print ih[0]       # prints 0x00 because this location is blank

2.5   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.

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

>>> ih.tofile(sio, format='hex')

NOTE: using IntelHex.tofile is recommended way.

Class IntelHex has 3 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).

Example:

>>> 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')

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))

2.6   Merging two hex files

IntelHex supports merging two different hex files into one. This is done by initializing one IntelHex object with data and calling its merge method:

>>> original = IntelHex("foo.hex")
>>> new = IntelHex("bar.hex")
>>> original.merge(new, overlap='replace')

Now original will contain foo.hex merged with bar.hex. The overlap parameter specifies what should be done when memory locations in the original object overlap with locations in the new object. It can take three options:

• error -- stop and raise an exception (default)
• ignore -- keep data from the original that contains data at overlapped address
• replace -- use data from the new object that contains data at overlapped address

You can merge only part of other hex file by using slice index notation:

>>> original = IntelHex("foo.hex")
>>> new = IntelHex("bar.hex")
>>> original.merge(new[0x0F:0x3F])

2.7   Creating Intel Hex files from scratch

Some facilities are provided for synthesizing Intel Hex files from scratch. These can also be used to modify a hex file in place. Just as you can use indexed reads to retrieve data, you can use indexed writes to modify the file, e.g.:

>>> ih[1] = 0x55 # modify data at address 1

A common usage would be to read a hex file with IntelHex, use the above syntax to modify it, and then write out the modified file. The above command can be used on an empty IntelHex object to synthesize a hex file from scratch.

Another important feature helps work with C strings via putsz/getsz, e.g.:

>>> ih.putsz(0x100,"A string")

This places "A string" followed by a terminating NULL in address 0x100. The getsz method similarly retrieves a null terminated string from a specified address like so:

>>> ih.getsz(0x100)

This should retrieve the "A string" we stored earlier.

Additionally, puts/gets can be used to retrieve strings of specific length from the hex file like so:

>>> ih.puts(0x100,"data")
>>> ih.gets(0x100,4)

The second command should retrieve the characters 'd','a','t','a'. These methods do not use terminating NULLs, so the data need not be interpreted as a string. One usage of these commands comes from the Python struct module. This module allows the programmer to specify a C struct, and it will allow conversion between the variables and a packed string representation for use with puts/gets. For example, suppose we need to deal with a struct containing a char, a short, and a float:

>>> import struct
>>> formatstring = 'chf' # see Python docs for full list of valid struct formats
>>> ih.puts(0x10, struct.pack(formatstring,'a',24,18.6)) #put data in hex file
>>> (mychar,myshort,myfloat) = struct.unpack(formatstring, ih.gets(0x10,7)

Now mychar, myshort, and myfloat should contain the original data (assuming sizeof(float) = 4 on this platform, otherwise the size may be wrong).

2.8   Handling errors

Many of the methods in IntelHex throw Python exceptions during error conditions. These can be caught and handled using try...except blocks like so:

>>> try:
...     mystring = ih.gets(0x20,20)
>>> except intelhex.NotEnoughDataError:
...     print "There was not enough data at that location"

See the API docs for information about errors raised by IntelHex. They are all subclasses of IntelHexError, so the except block above could be used to catch all of them. If your application has a way to gracefully handle these exceptions, they should be caught. Otherwise, Python will exit with a descriptive error message about the uncaught exception.

See Appendix A for error classes hierarchy.

3.1   Script hex2bin.py

You can use hex2bin.py as handy hex-to-bin converter. This script is just front end for function hex2bin from intelhex package.

Usage:
    python hex2bin.py [options] INFILE [OUTFILE]

Arguments:
    INFILE      name of hex file for processing.
    OUTFILE     name of output file. If omitted then output
                will be writing to stdout.


Options:
    -h, --help              this help message.
    -p, --pad=FF            pad byte for empty spaces (hex value).
    -r, --range=START:END   specify address range for writing output
                            (hex value).
                            Range can be in form 'START:' or ':END'.
    -l, --length=NNNN,
    -s, --size=NNNN         size of output (decimal value).

Per example, converting content of foo.hex to foo.bin addresses from 0 to FF:

$ python hex2bin.py -r 0000:00FF foo.hex

Or (equivalent):

$ python hex2bin.py -r 0000: -s 256 foo.hex

3.2   Script bin2hex.py

You can use bin2hex.py as simple bin-to-hex convertor. This script is just frontend for function bin2hex from intelhex package.

Usage:
    python bin2hex.py [options] INFILE [OUTFILE]

Arguments:
    INFILE      name of bin file for processing.
                Use '-' for reading from stdin.

    OUTFILE     name of output file. If omitted then output
                will be writing to stdout.

Options:
    -h, --help              this help message.
    --offset=N              offset for loading bin file (default: 0).

3.3   Script hex2dump.py

This is a script to dump a hex file to a hexdump format. It is a frontend for dump function in IntelHex class.

Usage:
    python hex2dump.py [options] HEXFILE

Options:
    -h, --help              this help message.
    -r, --range=START:END   specify address range for dumping
                            (ascii hex value).
                            Range can be in form 'START:' or ':END'.

Arguments:
    HEXFILE     name of hex file for processing (use '-' to read
                from stdin)

3.4   Script hexmerge.py

This is a script to merge two different hex files. It is a frontend for the merge function in IntelHex class.

Usage:
    python hexmerge.py [options] FILES...

Options:
    -h, --help              this help message.
    -o, --output=FILENAME   output file name (emit output to stdout
                            if option is not specified)
    -r, --range=START:END   specify address range for output
                            (ascii hex value).
                            Range can be in form 'START:' or ':END'.
    --no-start-addr         Don't write start addr to output file.
    --overlap=METHOD        What to do when data in files overlapped.
                            Supported variants:
                            * error -- stop and show error message (default)
                            * ignore -- keep data from first file that
                                        contains data at overlapped address
                            * replace -- use data from last file that
                                         contains data at overlapped address

Arguments:
    FILES       list of hex files for merging
                (use '-' to read content from stdin)

You can specify address range for each file in the form:

    filename:START:END

See description of range option above.

You can omit START or END, so supported variants are:

    filename:START:     read filename and use data starting from START addr
    filename::END       read filename and use data till END addr

Use entire file content:

    filename
or
    filename::

4.1   Embedding into other projects

IntelHex should be easy to embed in other projects. The directory intelhex containing __init__.py can be directly placed in a depending project and used directly. From that project the same import statements described above can be used to make the library work. From other projects the import statement would change to:

>>> from myproject.intelhex import IntelHex

Alternatively, the IntelHex package can be installed into the site-packages directory and used as a system package.

In either case, IntelHex is distributed with a BSD-style license. This permits you to use it in any way you see fit, provided that the package is appropriately credited.