Interface between impact sensor and controller for a supplemental inflatable restraint system

摘要

A side impact sensor processes side acceleration signals and upon a crash event develops a deploy signal which comprises accurately timed pulses of preset duration including a single pulse wake up message and a multiple pulse deploy message. A single wire interface couples the deploy signal to a microprocessor in a central controller which manages deployment of side and frontal air bags and runs frontal impact algorithm. The pulse edges cause interrupts used to measure the pulse widths which are compared to stored values to verify the messages. A wake up pulse causes the microprocessor to give priority to an algorithm for processing the deploy message over the frontal algorithm and still service the frontal algorithm without degradation. Signal drivers in the side impact sensor impose sharp pulse edges for the deploy signal and sloping edges for other signals monitoring the state of health of the side sensor to reduce radiated emissions.