This paper presents the design and implementation of a technological literacy course in professional development training for a diverse group of in-service primary teachers in Hong Kong. A set of micro-controlling hardware was chosen such that not only the controlling and coding barriers are acceptable to the teachers but that their pupils can also adopt the easy-to-use hardware and software to create STEM projects in primary schools. The hands-on training seeks to broaden their technological experiences in various interfacing and sensing activities. The coding challenge is reduced by introducing visual programming, thereby allowing the learners to focus on real- world problems in the STEM disciplines. Details of the course are provided and the assessment projects by Engineering Design Process are illustrated in this paper. The quantitative evaluation of teachers in their micro-controlling experience is provided. Copyright © 2018 by IEEE.