JPS58220531A - Diagnosing circuit - Google Patents

Abstract

PURPOSE:To make it unnecessary to set an initial value of a circuit to be diagnosed at starting the diagnosis, and also to apply it easily to a circuit to be diagnosed containing such a circuit as it is impossible to set the initial value by said result, by starting an operation of a diagnosing circuit in accordance with operation period information of the circuit to be diagnosed. CONSTITUTION:A diagnosis start signal 18 is held by a holding circuit 11, and also is inputted to a flip-flop circuit 12. On the other hand, various operation period information 16-1 of a circuit to be diagnosed 16 is selected, and in accordance with this information, a signal showing the longest operation period of the circuit to be diagnosed 16 is generated by a generating circuit 17. An output signal 12-1 is synchronized to the longest operation period of the circuit to be diagnosed 16, is converted to a signal of variation point information by a differentiating circuit 13, and is applied to a reference signal generating circuit 14 which generates a reference signal for diagnosing an output signal of the circuit to be diagnosed 16. As a result, the output signal of the reference signal generating circuit 14 is synchronized with the output signal of the circuit to be diagnosed 16, and diagnosis is started by a compare-diagnosing part 15, and is continued until a diagnosis end signal 20 is inputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diagnostic circuit for a circuit to be diagnosed that includes a circuit whose output signal state cannot be uniquely determined at the start of diagnosis.

FIG. 1 shows a conventional circuit configuration. In FIG. 1, a diagnosis start signal 7 is held in a holding circuit 1 composed of a number of Nandt gates, and is further phase synchronized with a clock signal 8 in a seven-lip-flop circuit 2.

This phase-synchronized diagnosis start signal 2-1 is detected by a differentiating circuit 3, and is used to set the initial values of the circuit to be diagnosed 6 and the reference signal generation circuit 4 that generates the same output signal as this output signal. It is input as signal 3-1. After this,
The comparative diagnosis section 5 starts diagnosing the output signals of the reference signal generation circuit 4 and the circuit to be diagnosed 6.

However, the circuit to be diagnosed often includes circuit parts such as frequency divider circuits that do not require initial value settings, and in such cases, the circuit's initial value setting, such as a reset terminal, is The terminals are generally connected to a power source to stabilize the circuit. It is impossible to add a signal for setting an initial value for diagnosis to such a circuit, and a diagnosis circuit with a conventional configuration has significant restrictions on the circuit to be diagnosed.

An object of the present invention is to provide a diagnostic circuit that can avoid the above-mentioned drawbacks by starting the operation of one diagnostic circuit based on the operation cycle information of the circuit to be diagnosed, contrary to the conventional type.

The diagnostic circuit of the present invention includes: a holding circuit for a diagnosis start signal of a logic circuit; a generating circuit for generating a signal indicating the longest operating cycle of the circuit to be diagnosed based on operating cycle information of the circuit to be diagnosed; A flip-flop circuit for phase synchronizing with the longest operating cycle of the circuit, a differentiating circuit for its output signal, a reference signal generation circuit that should indicate its contents, and a comparative diagnosis between its output signal and the output signal of the circuit to be diagnosed. has a department;
The present invention is characterized in that the longest operating cycle is determined based on the operating cycle information of the circuit to be diagnosed, and the reference signal generating circuit is operated in accordance with the longest operating cycle.

Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 2 shows an embodiment of the present invention, and Fig. 3 is a timing diagram showing its operation. In FIG. 2, the diagnosis start signal 18
is held in a holding circuit 11 composed of a number of Nant gate circuits, and is further input to a flip-flop circuit 12. On the other hand, various operating cycle information 16-1 of the circuit to be diagnosed 16 is selected, and based on this information, a signal indicating the longest operating cycle of the circuit to be diagnosed 16 is generated in the generating circuit 17.

By applying this signal to the clock input terminal T of the flip-flop circuit 12, the output signal 12-1 becomes a signal synchronized with the longest operating cycle of the circuit to be diagnosed 16. This signal 12-1 is converted into a signal of change point information by a differentiating circuit 13, and is applied to a reference signal generating circuit 14 which generates a reference signal for diagnosing the output signal of the circuit 16 to be diagnosed. As a result, the output signal of the reference signal generation circuit 14 is synchronized with the output signal of the circuit to be diagnosed 16, and the comparison diagnosis section 15
The diagnosis is started and continues until the diagnosis end signal 2o is input.

As is clear from the above explanation, according to the present invention, there is no need to set the initial value of the circuit to be diagnosed at the start of diagnosis in the conventional type, and this makes it impossible to set the initial value. It can also be easily applied to circuits to be diagnosed including circuits.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional diagnostic circuit for logic circuits, FIG. 2 is a configuration diagram showing an embodiment of the diagnostic circuit according to the present invention, and FIG. 3 is a timing diagram showing its operation. It is a diagram. 1.11...Nant gate circuit, 2.12...
...Flip-flop circuit, 3.13...
Differentiation circuit, 4.14...Reference signal generation circuit, 5
．． 15... Comparative diagnosis section, 6.16...
Circuit to be diagnosed, 17...Signal generation circuit. l 1 % Q ” 'N pre-harvest

Claims (1)

[Claims] a holding circuit for a diagnosis start signal of a logic circuit; a generating circuit for generating a signal indicating the longest operating cycle based on operating cycle information of the circuit to be diagnosed; and a circuit for generating a signal indicating the longest operating cycle of the circuit to be diagnosed; It has a 7-lip 70-tube circuit for synchronization, a differentiation circuit for its output signal, a reference signal generation circuit, and a comparison diagnosis section for comparing its output signal with the output signal of the circuit to be diagnosed. A diagnostic circuit characterized in that a longest operating cycle is determined based on operating cycle information, and the reference signal generating circuit is operated in accordance with the longest operating cycle.