In my earlier post “S-Record Generation with gcc for ARM/Kinetis” I documented how to have the ARM GNU gcc toolchain to produce a S19 (Motorola (or now Freescale) S-Record) file. Here are a few more tips on that subject:

1. Changing length of S-Records
2. Only using 32bit addresses
3. Combining S19 files

Changing the Length of S-Record Lines

Many S-Record reading tools (or bootloader) have a limit how long a S19 line can be. By default, the GNU objcopy produces this:

S01200004652444D5F4D61737465722E68657886
S113000000300020598000009D540000A9540000D5
S1130010B5540000C1540000CD540000D954000070
S1130020E5540000F1540000FD540000C13A000002

Using the option

--srec-len=

I can get shorter (or longer) lines:

S01200004652444D5F4D61737465722E68657886
S143000000300020598000009D540000A9540000B5540000C1540000CD540000D9540000E5540000F1540000FD540000C13A00000955000015550000E93A0000893A0000C1
S1430040215500002D5500003955000045550000515500005D5500006955000075550000815500008D55000099550000A5550000FD7A000069760000B1550000BD5500006E
S1430080C9550000FD4900001D510000D5550000E1550000ED550000F955000005560000115600001D5600002956000035560000415600004D560000595600006556000097

💡 The length covers both address, data and crc fields.

Forcing 32bit S3 Records

To use only S3 (32bit address) records, then the option

--srec-forceS3

is useful. This uses S3 records for lines which would otherwise be S1 or S2 records:

S01200004652444D5F4D61737465722E68657886
S3150000000000300020598000009D540000A9540000D3
S31500000010B5540000C1540000CD540000D95400006E
S31500000020E5540000F1540000FD540000C13A000000

Combining and Merging S19 Files

For a bootloader it is interesting to combine to S19 files (e.g. the application file with the bootloader file). Unfortunately the GNU objcopy cannot handle this. But the Burner utility (see S-Record, Intel Hex and Binary Files) can do this 🙂

The burner has following command line language definition (from the manual):

StatementList = Statement {Separator Statement}.
Statement = [IfSat | ForStat | Open | Send | Close | Pause 
             | Echo | Format | SFormat | Origin | Len 
             | BusWidth | Parity | SwapByte | Header 
             | BaudRate | DataBit | UndefByte 
             | Destination | AssignExpr | SLineLen].
IfStat = "IF" RelExpr "THEN" StatementList
             ["ELSE" StatementList] "END".
Assign = ("=" | ":=").
ForStat = "FOR" Ident Assign SimpleExpr "TO" SimpleExpr
               "DO" StatementList "END".
Open = ("OPENFILE" String) | ("OPENCOM" SimpleExpr).
Send = ("SENDBYTE" | "SENDWORD") SimpleExpr String.
Close = "CLOSE".
Pause = "PAUSE" [String].
Echo = "ECHO" [String].
Format = "format" Assign ("freescale" | "intel" | "binary").
SFormat = "SRECORD" Assign ("Sx" | "S1" | "S2" | "S3").
Origin = "origin" Assign SimpleExpr.
Len = "len" Assign SimpleExpr.
BusWidth = "busWidth" Assign ("1" | "2" | "4").
Parity = "parity" Assign ("none" | "even" | "odd").
SwapByte = "swapByte" Assign ("yes" | "no").
Header = "header" Assign string.
BaudRate = "baudRate" Assign ( "300" | "600" | "1200" 
                             | "2400" | "4800" | "9600" 
                             | "19200" | "38400").
DataBit = "dataBit" Assign ("7" | "8").
UndefByte = "undefByte" Assign SimpleExpr.
Destination = "destination" Assign SimpleExpr.
SLineLen = "SLINELEN" Assign SimpleExpr.
AssignExpr = Ident Assign SimpleExpr.
RelExpr = SimpleExpr {RelOp SimpleExpr}.
RelOp = "=" | "==" | "#" | "<>" | "!=" | "<" 
            | "<=" | ">" | ">=".
SimpleExpr = ["+" | "-"] Term {AddOp Term}.
AddOp = "+" | "-".
Term = Number | String | Ident.
Number = 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | {Number}
Ident = "i".
String = '"' {char} '"'.

I have two S19 files in my FLASH output folder: Part1.S19 and Part2.S19. I want to merge and combine them into merge.S19. Using the above syntax, I write my burner.bbl file as:

/* open destination file: */
OPENFILE "%FLASH_DIR%/Merge.S19"
/* set format to S19: */
format=motorola
/* we are sending byte by byte: */
busWidth=1
/* start at address zero: */
origin=0
/* cover the full flash range */
len=0x1000000
/* no destination offset to add: */
destination=0
/* use standard record format */
SRECORD=Sx
/* now send to the files to merge them into one: */
SENDBYTE 1 "%FLASH_DIR%/Part1.S19"
SENDBYTE 1 "%FLASH_DIR%/part2.S19"
/* close output file */
CLOSE

I’m using an environment variable %FLASH_DIR% to keep things portable.

In the (post)build step I’m passing it as variable to the burner:

"${MCU_TOOLS_HOME}/prog/piper.exe" "${MCU_TOOLS_HOME}/prog/burner.exe" -F="${ProjDirPath}\burner.bbl" -Env"FLASH_DIR=${ProjDirPath}\FLASH"

With this, I get the two S19 files merged:

❗ The post build step is only executed if something is built.

Summary

The GNU objcopy has basic S19 file generation support which is enough for simple things. If I need to do advanced scripts, I’m using the burner utility. The burner utility has a scripting language to automate many things dealing with object files and programming files.

Happy S-Recording