Intel hex file checksum 32 bit#
Intel hex file checksum code#

This 16 bit Linear Base Address, specified in the data area, is used to obtain a full 32 bit address range when combined with the address field of type ' 00' records. Type ' 04' records are used to pre-set the Linear Base Address. The data field of type ' 03' records contain 4 bytes, the first 2 bytes represent the value to be loaded into CS, the last 2 bytes are the value to be loaded into IP. The byte count of type ' 03' record is $04, because 4 data bytes will be sent. This starting address will be loaded into the CS and IP registers of the processor.ДЇor normal file transfers the type ' 03' records can be ignored.

Intel hex file checksum code#

So if you would upload a file to an Intel based development board, the starting address of the code can be specified with this record type. They are used to specify the start address for Intel processors, like the 8086. These records don't contribute to file transfers. The data field of the type ' 02' record contains the actual Extended Segment address.Д«its 3.0 of this Extended Segment address always should be 0! The byte count field will be $02 (the segment address consists of 2 bytes). The address field of a type ' 02' record must be $00. The Segment address is multiplied by 16 and then added to all subsequent address fields of type ' 00' records to obtain the effective address.Д«y default the Extended Segment address will be $0000, until it is specified by a type ' 02' record. With this segment address it is possible to send files of up to 1Mb in length. These records are used to pre-set the Extended Segment Address. The byte count and the address field of this record must always be $00.Д«ecause the contents of this record type is fixed, the checksum field is always the same ($FF). The receiver of the file will stop waiting for new records after receiving this record.

This will not produce a carry into the next Segment or Linear Base Address, so addressing space is wrapped back! The address in the address field is 16 bits, so a rollover from $FFFF to $0000 can occur.

The 1st data byte of the record is stored in the address specified by the address field of the record (plus the pre-set Segment or Linear Base Address).ДЄfter that the address is incremented and the next data byte is stored on the next address. The real data are sent using this record type. Target address = ulba*65536+ aaaa Record Type The formula to calculate the target address in case of Upper Linear Base Address mode is: In this case the address space is expanded to 32 bits, which gives us a total range of 4Gb. In case of Upper Linear Base Address mode the upper 16 bits of the 32 bit address are pre-set by a special record type. The formula to calculate the target address in case of Extended Segment mode is: The Extended Segment address is pre-set by 16-bits, given in a special record type. This will enable us to send files with a total length of 1Mb. In case of a Extended Segment Address this segment is added to the address field of the record, like in Intel 16 bit processors, to obtain a 20 bit address. Therefore Intel designed two extra record formats with which it is possible to pre-set an Extended Segment Address or Upper Linear Base Address. However this will only allow us to send files with a maximum size of 64kb. Normally the address aaaa is used to store the first data byte of the record. The file may also contain address gaps to skip a portion of unused memory. The order of addresses in the records of a file is not important. The address is represented by a 4 digit hex number (2 bytes), with the MSB first. This is the address where the first data byte of the record should be stored.ДЄfter storing that data byte, the address is incremented by 1 to point to the address for the next data byte of the record.ДЄnd so on, until all data bytes are stored.

It is not recommended to send too many data bytes in a record for that may increase the transmission time in case of errors.ДЄlso avoid sending only a few data bytes per record because the address overhead will be too heavy in comparison to the payload. Usually records have 32 data bytes, but any number between 0 and 255 is possible. The byte count cc counts the actual data bytes in the current record. Interpretation of a record should be case insensitive, so it does not matter if you use a.f or A.F. In fact, apart from the 1st colon and the End Of Line (EOL), no other characters than 0.9 and A.F are allowed in a record. No spaces or tabs are allowed in a record. cc+aaH+aaL+rr+sum(dd)+ss=0 Record BeginД®very record begins with a colon (ASCII value $3A).