DIAGNOSTIC CIRCUIT OF PULSE OUTPUT

摘要

PURPOSE:To enable prevention of output of abnormal data to the outside from a pulse output package (PPO) by a method wherein the diagnosis of a pulse generated for self-diagnosis in a pulse output circuit is conducted according to a specification address from CPU. CONSTITUTION:PPO sends pulse data from CPU to a pulse output circuit 2 through a data buffer 1 and converts them into a pulse width. A pulse thus converted is distinguished between an outside output pulse and a pulse for self-diagnosis by a data selector 3 in accordance with address specification from the CPU. The pulse width for self-diagnosis is inputted to a pulse conversion circuit 4, together with a pulse generation reference clock, and outputted as a pulse train of the same phase with the reference clock. This pulse train is inputted as a clock of FF incorporated in a binary counter 5 and converted into 8-bit parallel data being the same with the ones received by the PPO from the CPU. These data obtained through conversion are returned to the CPU and compared with the data written in the PPO by the CPU, and thereby the diagnosis can be performed.