We consider self-testing of complete wireless nodes in the field through a low-energy software-based selftest (SBST) method. Energy consumption is optimized both for individual components such as a CPU, embedded memories, and an RF module, as well as at the system level, considering the interplay between module tests. We first derive a scheme for softwarebased tests with the least amount of cycles and with operands of least Hamming distance and weight. Time interleaving of module tests at the system level further reduces the overall test energy consumption.