CS238087B1 - Wiring for automatic starting of the microcomputer - Google Patents

Abstract

Through the connection circuits, when the functional unit is working properly, a negative pulse for the trigger multivibrator regularly arrives, at the output of which there is then a permanent level of log 0. If the functional unit reaches an indeterminate state, the trigger pulses fail and the level of log 1 appears at the outputs of the trigger multivibrator. This change activates the first auxiliary multivibrator, which sends a signal over the bus to set the microcomputer to the initial state.

Description

The invention relates to a circuit for automatic resetting of the microcomputer.

In automatic measuring systems and a built-in microcomputer, one of the serious problems is the indeterminate state of some functional unit working in an unattended location.

eg interference from the mains, even if its technical and software equipment is OK. It is only possible to return the unit to the correct state after the microcomputer has been reset, which is performed manually by the operator. This disadvantage can be eliminated by automatic restart circuits. It can be assumed that such circuits exist but are not known to us.

The purpose of the invention is to eliminate the disadvantage of manually starting the microcomputer. According to the principle of the invention, this is achieved by connecting the trigger multivibrator input to the microcomputer bus via the connection circuits, the output of which is connected to the first NOR gate input via the first auxiliary multivibrator. The second auxiliary multivibrator output is connected to the second NOR gate input. The NOR gate output is connected to the microcomputer bus and to the trigger input of the trigger multivibrator.

The wiring for automatic resetting of the microcomputer is simple and allows the microcomputer to be reset from the indeterminate state immediately as soon as the functional unit is indeterminate.

An example of a circuit according to the invention is further described with reference to the drawing. In the block diagram, an input is connected to the microcomputer bus 3

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- 2 connection circuits A. Their output is connected to the trigger multivibrator input B. The trigger multivibrator output B is connected to the first NOR gate B input via the first auxiliary multivibrator D. The second input of this gate E is connected to the output of the second auxiliary multivibrator C. The gate output E is connected to the microcomputer bus S and to the reset input of the trigger multivibrator B.

A negative pulse for the trigger multivibrator B is regularly received via the connection circuits A of the properly functioning functional unit. The time constant of the trigger multivibrator B is selected so that the duration of the generated pulse is about 15% longer than the time between two incoming negative trigger pulses.

At the output of the trigger multivibrator B there is a constant level of log O. If the functional unit gets indeterminate, the trigger pulses fail and at the output of the trigger multivibrator B the level of log 1 appears. This change activates the first auxiliary multivibrator D via bus S microcomputer signal to reset microcomputer to the default state - resin-. The second auxiliary multivibrator C prevents the entire wiring from becoming astable.

The automatic start-up circuit according to the invention is universal for all functional units with a built-in microcomputer. Wiring eliminates the need for manual operation.

Claims (1)

SUBJECT OF THE INVENTION A circuit for automatic resetting of the microcomputer, characterized in that the trigger multivibrator input (B> is connected to the microcomputer bus (S) via the connection circuits (A), the output of which is connected to the first gate input via the first auxiliary multivibrator (D). NOR type, whose second input is connected to the output of the second auxiliary multivibrator (C), while the NOR gate output (E) is connected to the microcomputer bus (S) and to the trigger input of the trigger multivibrator (B).