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Power-On Self Testing of Communication Interface

IP.com Disclosure Number: IPCOM000059738D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Inui, T: AUTHOR [+2]

Abstract

A method of testing the error detection function of power on initial function test program is applicable to machines connected on data transmission lines, such as terminal unit that employs a USART (universal synchronous/asynchronous receiver/transmitter) circuit module. Machines having an MPU (microprocessor unit) usually have programs that test functions of the machines themselves. POST (power on self- test) is invoked by power-on reset (POR) signal and performs test functions after fetching a first instruction from ROM (read-only memory), then testing MPU, ROS (read-only storage), RAM (random-access memory), video interface, etc.

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Power-On Self Testing of Communication Interface

A method of testing the error detection function of power on initial function test program is applicable to machines connected on data transmission lines, such as terminal unit that employs a USART (universal synchronous/asynchronous receiver/transmitter) circuit module. Machines having an MPU (microprocessor unit) usually have programs that test functions of the machines themselves. POST (power on self- test) is invoked by power-on reset (POR) signal and performs test functions after fetching a first instruction from ROM (read-only memory), then testing MPU, ROS (read-only storage), RAM (random-access memory), video interface, etc. The USART (Intel 8251A, NEC PD8251AFC/D, TOSHIBA 8251AP) accepts data characters from the MPU in parallel format and then converts them into a continuous serial data stream for transmission, and vice versa. The MPU can read the complete status of the USART at any time. These include data transmission errors and control signals, such as Sync/Break Detect (SYNDET) and Transmit Empty (TxEMPTY). The proposed method is based on an appropriate wrap circuit, using a Send Break command to generate various irregular data. The Send Break On/Off command to the USART produces the TxD (Transmit Data) signal, which is a serial output signal, "low" or "high" state, respectively. With these characteristics of the Send Break command, we can generate any data streams by Send Break On/Off with appropriate...