The HI-3717 is targeted at digital flight data recorder applications and may be used in the recorder itself, the data acquisition unit or the quick access recorder. The device communicates with an external microcontroller via a 4-wire Serial Peripheral host Interface (SPI) and provides Harvard Bi-Phase (HBP) and Bi-Polar Return-to-Zero (BPRZ) channels with encoders/decoders. Dedicated line drivers and line receivers allow direct connection to the ARINC 717 bus.