Bascom-AVR is probably the best BASIC compiler for Atmel AVR microcontrollers. If you have previous experience with MS QuickBasic or VisualBasic, you will feel right at home. The demo version does not expire, but is limited to 4 kB of compiled code. https://www.mcselec.com/index.php?option=com_content&task=view&id=14&Itemid=41