JPS5843053A - Microprocessor - Google Patents

Abstract

PURPOSE:To simplify the work of a microprocessor, by providing such function to the microprocessor that sets an optional output signal at a high level of impedance by applying the signal to a specified input terminal. CONSTITUTION:A signal 310 is equal to a signal 305, i.e., the control signal to a driver 311 of a BSRQ0. When this signal is turned on, the output of the driver 311 is set a high level of impedance. such microprocessor 301 is used to detect the circuit error for a bus controller 302 and a data processor 304. Thus the signals 310 and 306 are turned on and off respectively. As a result, the processor 301 inputs the signal to the 305 from outside without affecting the controller 302 and the processor 304 and can decide freely the value. The terminals excepting the output terminals (A0-A3) are set at a high level of impedance. Thus an error or fault can be easily detected for the peripheral circuits of the processor 301.

Description

DETAILED DESCRIPTION OF THE INVENTION 7 The present invention is housed in one package, includes an arithmetic unit and a register, and provides information on the contents of the register.

The present invention relates to a microprocessor having a function of performing arithmetic processing.

~ Iku Bu Se Sumon Use 1 When trying to control various devices - Generally, the purpose is to control the program that drives the microprocessor, i.e., the software and the input/output signals of the microprocessor 106 is an external input signal to the peripheral circuit.

do not have.

Error in peripheral circuit design9. The work of trying to find or see the point of failure is 1) Power signal to the peripheral circuit 102) 1
It is a common method to check o3, 1o4 and 106 places, but conventional microprocessors spontaneously carry out critical reading and data input/output operations, so the value of signal 103 is , often unstable. Also, even if Ma, Iklop.

The processor is in a stopped state, and the value of signal 103 is.

Even if it were stable, it would be difficult to set that value to an arbitrary value for testing purposes. Therefore, for inspection,
The microprocessor itself had to be removed from the printed circuit board and signal 103 had to be input with an appropriate value from another signal source. The present invention simplifies complicated work by giving a microprocessor the ability to put any output signal into a high impedance state by applying a signal to a specific input terminal. FIG. 2 shows an example of a conventional microprocessor output signal control method. In the figure.

The device 203 is a data bus signal, and 204 is a data processing device connected to the data bus. Signal 205, ie, BSRQO, is a bus use request signal from microprocessor 201 to bus control device 202, and signal 206 is a bus use permission signal for microprocessor 201.

Signals 207 and 208 are respectively sent to the data processing device 2.
These are the use request from 04 and the permission signal. driver 20
9 is a driver for the output terminal of the microprocessor, and when signal 2 is ON, it enters a high impedance state.

When the microprocessor 201 intends to output data to the data bus, it o'NKs the signal 20B (BSRQO). When BSRQo is turned on, the bus controller 202 determines whether or not to permit the microprocessor to use the data bus by comparing it with another input signal, i.e., the value of BSRQl. turns BSAVO ON, but the microprocessor 20
1 is.

When BSAVo turns ON, it is determined that the right to use one data bus has been obtained, and data is output to terminals Ao-As. In such a system, when trying to discover a circuit error in the bus control device 202 and other data processing devices 2o4, the signal BSRQ is detected.

Fixed to either ON or OFF state.

AoLA's and signal BS, R'Q1. It is necessary to test B'sA/1. If BSAVo is turned OFF, the microprocessor's output terminal is in a high impedance state, so the signals A0 to A3 will not be disturbed by the microprocessor, but the signal BS
Since RQO is not in high impedance state 5,
Others are determined by the output of the microprocessor. Therefore, in order to set BSRQO to a desired value, 1. The microprocessor converts such values into BS
Create a program to output to RQO, or
Remove the macro processor itself and connect another signal source to B.
I had to connect to SRQO.

The present invention provides a method to solve the above problems.

FIG. 3 shows two embodiments of the present invention.

301 to 309 in the figure correspond to 201 to 209 in the second figure, respectively, and have the same functions. Signal 301 is signal 30
6, which is a control signal for the BSRQO driver 311. When this signal is turned ON, the output of the driver 311 becomes a high-indance state. In the system shown in FIG. 3 using such a microprocessor 301, when trying to discover a circuit error in the bus control device 302 and data processing device 304, by turning on the signal ago and turning off the signal 306, the microprocessor 301 can be detected. processor 30
1 has no effect on 302 and 3.04 K,
A signal can be input to the signal 306 from the outside and its value can be freely determined.

A control input terminal is provided to set the terminals other than the output terminals (AO to A3 in FIG. 3) that are the data path to a high impedance state, and
By applying logic signals, signals other than the data path can also be placed in a high impedance state.

This makes it easier to detect errors and failures in systems using microprocessors, and the peripheral circuits of microprocessors.

During system development, the microprocessor is often mounted on a printed circuit board via a socket, so it may not be difficult to remove it, but after development is complete, it may be necessary to solder it directly to the printed circuit board. It is often attached. If such a system fails, it is difficult to remove the microprocessor package, so the present invention is particularly effective.

In the description of the above embodiment, a case was explained in which only terminals other than the data input/output path are set to a high impedance state by applying a signal to a specific input terminal. It is clear that a function may be attached to a specific input terminal such that the terminal serving as the input/output path and the other output terminals are simultaneously in a high impedance state.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the connection relationship between a microprocessor and peripheral circuits, Fig. 2 is a block diagram showing an example of a system using a conventional microprocessor, and Fig. 3 is a diagram showing an example of a system using a conventional microprocessor. 301 showing an example of a system using a microprocessor in the embodiment, Microprocessor 9.302...
...Data bus signal, 304°305...
...Data processing device, 311...Dryno (. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 03 105 Figure 2 04

Claims (1)

[Claims] The terminal includes a terminal serving as a data input/output route, and a wooden terminal on the output terminal used for a purpose other than the data route, and by applying a signal to the input terminal, at least the data route other than the data route can be A microprocessor characterized by having an added function of setting all, t, or a part of output terminals used for a purpose to a high manpedance state.