We extend a model based development approach for software components of embedded systems by a model based testing framework. We motivate by describing challenges a developer has to face when developing embedded software and present as a solution an UML-centric development approach. We introduce a testing framework that allows specification of test cases for UML class models using UML sequence- and use-case-diagrams. These test cases define participating objects and their messages including parameters, loops, control structures, inclusion of other collaborations and time constraints. These diagrams are verified against the real system-response of the software under test. We employ a commercial in-circuit emulator to record method calls, object identities and their parameters on C source-code level as messages with minimal impact on system performance and map these back to model level to verify them against the specified model.