Provided by: libgps-dev_3.9-3_amd64 
NAME
srec - Motorola S-record record and file format
DESCRIPTION
Motorola S-records are a form of simple ASCII encoding for binary data. This format is
commonly used for firmware uploads to GPSes, industrial robots, and other kinds of
microcontroller-driven hardware. It has several convenient properties, including
inspectability, easy editing with any text editor, and checksumming for verification of
transmission across noisy serial lines.
An S-record file consists of a sequence of specially formatted ASCII character strings. An
S-record will be less than or equal to 78 bytes in length.
The order of S-records within a file is of no significance and no particular order may be
assumed.
The general format of an S-record follows:
+-------------------//------------------//-----------------------+
| type | count | address | data | checksum |
+-------------------//------------------//-----------------------+
type
A char[2] field. These characters describe the type of record (S0, S1, S2, S3, S5, S7,
S8, or S9).
count
A char[2] field. These characters when paired and interpreted as a big-endian
hexadecimal integer, display the count of remaining character pairs in the record.
address
A char[4,6, or 8] field. These characters grouped and interpreted as a big-endian
hexadecimal integer, display the address at which the data field is to be loaded into
memory. The length of the field depends on the number of bytes necessary to hold the
address. A 2-byte address uses 4 characters, a 3-byte address uses 6 characters, and a
4-byte address uses 8 characters.
data
A char [0-64] field. These characters when paired and interpreted as hexadecimal
values represent the memory loadable data or descriptive information.
checksum
A char[2] field. These characters when paired and interpreted as a big-endian
hexadecimal integer display the least significant byte of the ones complement of the
sum of the byte values represented by the pairs of characters making up the count, the
address, and the data fields.
Each record is terminated with a line feed. If any additional or different record
terminator(s) or delay characters are needed during transmission to the target system it
is the responsibility of the transmitting program to provide them.
There are 9 record types, as follows:
S0
The type of record is 'S0' (0x5330). The address field is unused and will be filled
with zeros (0x0000). The header information within the data field is divided into the
following subfields.
1. mname is char[20] and is the module name.
2. ver is char[2] and is the version number.
3. rev is char[2] and is the revision number.
4. description is char[0-36] and is a text comment.
Each of the subfields is composed of ASCII bytes whose associated characters, when
paired, represent one byte hexadecimal values in the case of the version and revision
numbers, or represent the hexadecimal values of the ASCII characters comprising the
module name and description.
S1
The type of record field is 'S1' (0x5331). The address field is interpreted as a
2-byte big-endian address. The data field is composed of memory loadable data.
S2
The type of record field is 'S2' (0x5332). The address field is interpreted as a
3-byte big-endian address. The data field is composed of memory loadable data.
S3
The type of record field is 'S3' (0x5333). The address field is interpreted as a
4-byte big-endian address. The data field is composed of memory loadable data.
S5
The type of record field is 'S5' (0x5335). The address field is interpreted as a
2-byte big-endian value and contains the count of S1, S2, and S3 records previously
transmitted. There is no data field.
S7
The type of record field is 'S7' (0x5337). The address field contains the starting
execution address and is interpreted as a 4-byte big-endian address. There is no data
field.
S8
The type of record field is 'S8' (0x5338). The address field contains the starting
execution address and is interpreted as a 3-byte big-endian address. There is no data
field.
S9
The type of record field is 'S9' (0x5339). The address field contains the starting
execution address and is interpreted as a 2-byte big-endian address. There is no data
field.
EXAMPLE
Shown below is a typical S-record format file.
S00600004844521B
S1130000285F245F2212226A000424290008237C2A
S11300100002000800082629001853812341001813
S113002041E900084E42234300182342000824A952
S107003000144ED492
S5030004F8
S9030000FC
The file consists of one S0 record, four S1 records, one S5 record and an S9 record.
The S0 record is comprised as follows:
• S0 S-record type S0, indicating it is a header record.
• 06 Hexadecimal 06 (decimal 6), indicating that six character pairs (or ASCII bytes)
follow.
• 00 00 Four character 2-byte address field, zeroes in this example.
• 48 44 52 ASCII H, D, and R - "HDR".
• 1B The checksum.
The first S1 record is comprised as follows:
• S1 S-record type S1, indicating it is a data record to be loaded at a 2-byte address.
• 13 Hexadecimal 13 (decimal 19), indicating that nineteen character pairs, representing
a 2 byte address, 16 bytes of binary data, and a 1 byte checksum, follow.
• 00 00 Four character 2-byte address field; hexidecimal address 0x0000, where the data
which follows is to be loaded.
• 28 5F 24 5F 22 12 22 6A 00 04 24 29 00 08 23 7C Sixteen character pairs representing
the actual binary data.
• 2A The checksum.
The second and third S1 records each contain 0x13 (19) character pairs and are ended with
checksums of 13 and 52, respectively. The fourth S1 record contains 07 character pairs and
has a checksum of 92.
The S5 record is comprised as follows:
• S5 S-record type S5, indicating it is a count record indicating the number of S1
records
• 03 Hexadecimal 03 (decimal 3), indicating that three character pairs follow.
• 00 04 Hexadecimal 0004 (decimal 4), indicating that there are four data records
previous to this record.
• F8 The checksum.
The S9 record is comprised as follows:
• S9 S-record type S9, indicating it is a termination record.
• 03 Hexadecimal 03 (decimal 3), indicating that three character pairs follow.
• 00 00 The address field, hexadecimal 0 (decimal 0) indicating the starting execution
address.
• FC The checksum.
NOTES
• There isn't any evidence that Motorola ever made use of the header information within
the data field of the S0 record, as described above. This may have been used by some
third party vendors.
• The Unix manual page on S-records is the only place that a 78-byte limit on total
record length or 64-byte limit on data length is documented. These values shouldn't be
trusted for the general case.
• The count field can have values in the range of 0x3 (2 bytes of address + 1 byte
checksum = 3, a not very useful record) to 0xff; this is the count of remaining
character pairs, including checksum.
• If you write code to convert S-Records, you should always assume that a record can be
as long as 514 (decimal) characters in length (255 * 2 = 510, plus 4 characters for
the type and count fields), plus any terminating character(s). That is, in
establishing an input buffer in C, you would declare it to be an array of 515 chars,
thus leaving room for the terminating null character.
SEE ALSO
gpsd(8), gps(1), libgps(3), libgpsd(3), gpsfake(1). gpsprof(1).
AUTHOR
From an anonymous web page, itself claiming to have been derived from an old Unix manual
page. Now maintained by the GPSD project, which added endianness clarifications.