bump-blt-version

name	bump-blt-version
description	Bump the OpenBLT bootloader version marker (BLxx) in both required places - set_bl_bin_version.sh and BLT_CURRENT_VERSION in mpu_util.h. Use when the bootloader build has materially changed, or when the user asks to bump/increase the bootloader (BL) version.

Bump OpenBLT bootloader version marker

The bootloader version is a 4-char ASCII tag (BL07, BL08, ...) stored in the 3rd reserved DWORD of the bootloader vector table (flash 0x08000024). It is defined in TWO places that MUST change together, both tagged with the grep marker search:openblt_version. Background: CLAUDE.md section "OpenBLT Bootloader Version Marker".

Steps

1. Read the current version from firmware/hw_layer/ports/mpu_util.h:

   #define BLT_CURRENT_VERSION 0x37304C42
   

   This u32 is the ASCII tag in reverse (little-endian) byte order: 0x37304C42 = bytes 42 4C 30 37 = B L 0 7 -> current tag BL07.

2. Compute the new tag: increment the decimal number unless the user asked for a specific one (BL07 -> BL08; note BL09 -> BL10 changes BOTH digit characters). Derive the two encodings:

   • byte sequence: ASCII codes of the 4 chars, e.g. BL08 -> \x42\x4c\x30\x38
   • u32 constant: same bytes reversed, e.g. BL08 -> 0x38304C42

   Sanity helper (prints both encodings for a tag):

   TAG=BL08; printf '%s' "$TAG" | xxd -p; \
   printf '0x%s\n' "$(printf '%s' "$TAG" | xxd -p | fold -w2 | tac | tr -d '\n' | tr a-f A-F)"
   

3. Edit place 1 - firmware/bin/set_bl_bin_version.sh:

   • the comment line: # set ascii 'BL07' into third reserved DWORD of vector table
   • the printf bytes: printf '\x42\x4c\x30\x37'

4. Edit place 2 - firmware/hw_layer/ports/mpu_util.h:

   • the comment line: // ascii 'BL07' in reverse LBS byte order
   • the define: #define BLT_CURRENT_VERSION 0x37304C42

5. Verify consistency - the script bytes and the header constant must be byte-reversals of each other, and no old-tag stragglers remain:

   grep -rn "search:openblt_version" firmware/ | grep -v ChibiOS
   grep -n "printf" firmware/bin/set_bl_bin_version.sh
   grep -n "BLT_CURRENT_VERSION" firmware/hw_layer/ports/mpu_util.h
   

   Check by hand: printf \xAA\xBB\xCC\xDD must correspond to constant 0xDDCCBBAA, and both must spell the intended ASCII tag.

6. Commit both files in the SAME commit, together with (or referencing) the bootloader change that motivated the bump. Precedent: BL06 21e3d069285, BL07 438cf802ac8 (PR #9815). A bump with no bootloader change is meaningless - it only declares "this bootloader build differs".

Runtime effect (for the commit message / PR text)

ECUs flashed with the new full rusefi.bin report CURRENT from the show_blt_version console command; ECUs that only ever took rusefi_update.srec keep the old marker in flash and report UNEXPECTED, flagging that their bootloader is stale.