.SREC

Introduction

S-record is Motorola’s text format for binary data that is to be written into memory, such as the firmware for a microcontroller. Like Intel HEX, each line is one record holding a run of bytes as hexadecimal digits, the address they belong at and a checksum. It is common with NXP (formerly Motorola and Freescale) chips and is one of the output formats of most embedded toolchains.

Files are named .srec, .mot, or after the record types they use: .s19 for 16-bit addresses, .s28 for 24-bit and .s37 for 32-bit.

Structure

Every record is one line that starts with S and a digit giving the record type. After it come pairs of hexadecimal digits: a count of the bytes that follow, the address (2, 3 or 4 bytes depending on the type), the data and a checksum. The checksum is the ones’ complement of the lowest byte of the sum of the count, address and data bytes.

Type S0 is a header, usually holding a name. S1, S2 and S3 are data records with 16, 24 and 32-bit addresses. S5 and S6 give the number of data records, and S9, S8 and S7 end the file with a start address of 16, 24 or 32 bits.

S00F000068656C6C6F202020202000003C
S111003848656C6C6F20776F726C642E0A0042
S5030001FB
S9030000FC

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