Hello, This change is not related to Gnuk itself. I'm using tool/stlinkv2.py for FSM-55, too. FSM-55's MCU is STM32F0 and its core is Cortex-M0 (instead of Cortex-M3). I changed the code to be loaded to ST-Link/V2 with Cortex-M0, so that it works both for STM32F0 and STM32F1. Tested with FSM-55 and FST-01. --