I'm developing an application for a STM8S207C8 entirely in assembler. I found almost no documentation that could help me in my task, so I had to learn by practice. I learnt that STM8 core programming differs a lot from ST7 one. For instance, the stack is the best place for local variables, but you have to pay attention to stack frames (and to optimize them too). If you need some piece of advise on STM8 assembler programming, please, open a new topic and I'll will be glad to answer to your questions (if I can). Regards, EtaPhi