The current state of firmware testing is too complicated. Huge resources are spent on system tests that discover little bugs. For embedded firmware the correct interaction with microcontroller periphery (GPIO, CAN, ...) is essential. Drivers are programmed to utilize this periphery. Open loop tests offer the possibility to test these drivers in detail. Embedded platforms are based on drivers. Therefore a process to test drivers is critical to reliable platforms.   Open loop is a term used in control theory. Control theory aims to influence a process so that a given state is reached. Closed loop controllers continuously measure the output. The process is then influenced based on the difference between desired and actual state. Open loop controllers are not dependent on the output and influence the process in a blind way. This simplifies the design and use enormously.  Embedded systems are typically tested in a way that resembles closed loop controllers. Open loop principles can simplify the complexity so that tests are compact and readable. This talk will present the current state of embedded systems testing. It will explain how this relates to closed loop systems. Then an alternative approach is developed that is based on open loop principles.