Flash Bootloader Interaction

#!/usr/bin/env python3
# SBL download: first step in all reprogramming sequences
# SBL runs in RAM; never persisted as permanent flash (it is re-downloaded each session)

import udsoncan
from udsoncan.client import Client

def download_sbl(client, sbl_image_path: str):
    SBL_LOAD_ADDR = 0x70010000   # LMU RAM on Aurix TC3xx (not flash)
    sbl_image = open(sbl_image_path, 'rb').read()
    SBL_SIZE = len(sbl_image)

    # Step 1: RequestDownload for SBL (load to RAM, not flash)
    memloc = udsoncan.MemoryLocation(
        address=SBL_LOAD_ADDR, memorysize=SBL_SIZE,
        address_format=32, memorysize_format=32
    )
    resp = client.request_download(0x00, memloc)
    max_block = resp.service_data.max_block_length

    # Step 2: Transfer SBL
    block_size = max_block - 2
    seq = 1
    for offset in range(0, SBL_SIZE, block_size):
        chunk = sbl_image[offset:offset+block_size]
        client.transfer_data(seq & 0xFF, chunk)
        seq += 1

    # Step 3: Exit transfer; PBL verifies SBL integrity
    client.request_transfer_exit()

    # Step 4: Execute SBL via RoutineControl 0x0301 (OEM-specific routine to jump to SBL)
    # After this call, SBL is active and handles all subsequent 0x34/0x36/0x37/0x31
    resp = client.routine_control(0x01, 0x0301, bytes([
        (SBL_LOAD_ADDR >> 24) & 0xFF, (SBL_LOAD_ADDR >> 16) & 0xFF,
        (SBL_LOAD_ADDR >>  8) & 0xFF, (SBL_LOAD_ADDR >>  0) & 0xFF,
    ]))
    print(f"SBL execution: {'started' if resp.positive else 'FAILED NRC 0x' + format(resp.code,'02X')}")