New Functions for Existing Controllers
Unlike fullpass approaches, where the ECU is completely replaced by the prototyping system, bypassing is used to develop only individual parts of the ECU software from scratch. These run either on the external prototyping system (external bypassing) or directly on the ECU (internal bypassing, on-target prototyping). dSPACE has developed a comprehensive range of tools that support the different bypass methods, placing particular emphasis on the ability to switch between internal and external bypassing quickly and flexibly, without having to modify the function model.
This bypass method is an efficient approach to developing new software functions and optimizing existing controller strategies. The original ECU executes all the functions that can remain unchanged, while new algorithms run on the dSPACE prototyping hardware. The external bypass method provides the greatest possible flexibility during the design phase, since there are almost no resource constraints such as RAM, ROM (flash), processor performance, or I/O channels. Real-time behavior is guaranteed even for complex bypass functions. Any additional sensors and actuators that are needed can be connected directly to the prototyping system. dSPACE supports numerous interfaces to connect the prototyping system to the ECU, such as CCP, XCP or on-chip debug interfaces.
In internal bypassing, also called on-target prototyping, new functions are implemented directly on the existing ECU by using its free RAM and flash memory areas. No special rapid control prototyping hardware is needed. Because the new software functions are executed directly on the target hardware, there are no communication latencies to external systems, and the functions can be integrated into very fast control loops.