The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Chapter 13
Intel Hex
Like ASCII Hex, Intel Hex format stores bytes as ASCII codes representing hexadecimal
characters. But Intel Hex adds addressing and error-checking information for more flexible
programming and more reliable file transfer.
Each Intel Hex file consists of a series of records. Table 13-1 has more details about the
records and what they contain. You don’t have to understand everything about Intel Hex
format in order to use it, but the information can be useful if you run into problems and want
to examine the contents of a file.
Assembling a Program
When you assemble a program, the message Assembly Successful, or something similar,
means that the assembler found no errors that prevented it from creating the object file. If
you do see error messages, you’ll have to find out what’s wrong before continuing. The
listing file also includes the error messages, and these should help you track down any
problems.
Table 13-1. An Intel Hex file consists of a series of records , each of which
contains the the six elements below.
Name # Chars Description
Record Mark 1 Each record begins with a colon (:).
Record Length 2 Number of data bytes in the record.
Address Field 2 In data records, the address where the first data byte is to be stored, with
following bytes in sequence. In other record types, 0000.
Record type 2 There are four record types:
00 Data
01 End of File
02 Extended address
03 Start address
Data Field varies Contents depends on the record type:
00 Data to be programmed
01 Not used (empty)
02 Segment. For address fields larger than 64K, data is stored
beginning at (segment+10h)+address field.
03 Start address of program. Often unused.
Checksum 2 To calculate the checksum:
(1) Add the values of all of the bytes in a record.
(2) Take the 2’s complement of the result (Complement all bits and
add 1.)
(3) The checksum is the low byte of the result.
224 The Microcontroller Idea Book