After a successful reboot, run these commands to ensure full functionality:
AOT> version
# Must show your new version, e.g., App:v2.2.4
AOT> selftest all
copy tftp://192.168.1.100/AOT4221SR_v2.0.5.bin flash:system.img
Use this when the device is in production but accessible via CLI. aot4221sr firmware upgrade
# SSH into the switch (port 22)
ssh admin@192.168.1.1
Q: Do I lose my calibration data after an aot4221sr firmware upgrade?
A: No, provided you do not erase sector 0x0801E000-0x08020000. The aotflash_cli tool preserves this by default unless you use --full-erase.
Q: Can I downgrade the firmware?
A: Yes, but only if the bootloader version is compatible. Downgrading from v2.2.x to v1.9.x will trigger a factory reset of configuration parameters.
Q: How long does the upgrade take?
A: Over UART at 921600 baud, approximately 45 seconds. Over OTA with a 100 Mbps link, about 2 minutes. After a successful reboot, run these commands to
Q: The device is not responding after upgrade—LED shows rapid amber. What now?
A: This indicates a boot watchdog timeout. The upgrade likely corrupted the interrupt vector table. Perform a full chip erase (see Section 6) and reprogram.
write memory
reload
After reload, log back in and run show version to confirm the upgrade.
The AOT4221SR often lives in a dusty cabinet at a utility substation or on a factory floor. Follow these extra rules:
AOT> version
Typical output: AOT4221SR-Boot:v1.2.0 App:v1.9.2 HAB:Enabled
If the bootloader is older than v1.1.0, you must upgrade the bootloader first using a separate BIN file. After reload, log back in and run show
Before diving into the how, it is critical to understand the why. The AOT4221SR’s firmware stack is divided into three layers: the primary bootloader (PBL), the secondary bootloader (SBL), and the application firmware. Upgrading offers:
Critical Warning: Do not skip intermediate firmware versions if your device is more than two releases behind. The AOT4221SR’s EEPROM configuration structure changed between v1.8.x and v2.0.x. Skipping versions can corrupt the parameter storage region.