Crosstalk effects degrade the integrity of signals traveling on long interconnects and must be addressed during manufacturing testing. External testing for crosstalk is expensive due to the need for high-speed testers. Built-in self-test, while eliminating the need for a high-speed tester, may lead to excessive test overhead as well as overly aggressive testing. To address this problem, we propose a new software-based self-test methodology for systemon-chips (SoC) based on embedded processors. It enables an onchip embedded processor core to test for crosstalk in system-level interconnects by executing a self-test program in the normal operational mode of the SoC. We have demonstrated the feasibility of this method by applying it to test the interconnects of a processor-memory system. The defect coverage was evaluated using a system-level crosstalk defect simulation method.