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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 the GPSD project, which
       added endianness clarifications. There is a project page for gpsd
       here[1].

NOTES

        1. here
           http://gpsd.berlios.de/