JPS62168240A - Scan path circuit - Google Patents

Abstract

PURPOSE:To point out an abnormal area on a scan path by supplying the code information on the boundaries to the scan path from these boundaries divided for each hardware. CONSTITUTION:A diagnosis processor 1 produces the control commands to designate the desired actions for the fault diagnosis of a data processor 2 as well as the data to be set to scan paths 22-24 and sends them to the processor 2 via an interface 3. While the processor 1 receives the data outputted from those scan paths from the processor 2 via an interface 3. These produced control commands are set to a control command register 11 and the produced data are set to a data transmitting FF 12 at every bit and outputted to the interface 3. The data received from the processor 2 are set to a data receiving FF 13 at every bit and used within the processor 1. A counting means 14 detects the code information contained in the output data received from those paths 22-24 and counts the detecting frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scan path circuit for a data processing device, and more particularly to a scan path circuit including diagnostic means.

[Conventional technology]

Data processing devices have conventionally taken various measures to diagnose failures within the device. As one of the means,
Fault diagnosis using scan paths is being carried out.

The scan path is configured by connecting flip-flops within the device in a bit-serial manner, in addition to a normal processing bus that connects the flip-flops within the device using logic circuits.

The scan path takes out 1 bit of data from the shift end of the scan path by simultaneously shifting all flip-flops on the bus by 1 pin, and also takes out 1 bit of data from the input end.
Import bit data.

By repeating this one focus shift, data is taken out from all the flip-flops on the scan path and new data is set in all the flip-flops on the scan path.

Furthermore, it is also possible to change part of the flip-flops on the scan path by changing part of the data that has been taken out from the scan path and returning it to the scan path.

Diagnosis of failures in data processing equipment uses these functions of the scan path to send data useful for diagnosis to the input flip-flops of the parts of the equipment that are to be diagnosed, and to output data from the parts to be diagnosed. This is done by extracting data that has passed through a diagnostic point from a flip-flop that stores the data, and processing the extracted data with a diagnostic processing device.

[Problem that the invention seeks to solve]

In fault diagnosis using the conventional scan path described above,
Prior to diagnosis, we confirm that there are no abnormalities in the scan path. For this confirmation, “1” on the scan path
Assuming a fault fixed at "" and a fault fixed at "0", data of 10" and "1" are input from the input end of the scan path, and the data is shifted on the scan path and taken out from the shift end. If there is a fault fixed at "1" on the "scan path", data of "0" cannot be taken out from the shift end, and if there is a fault fixed at "0", data of "1" cannot be taken out from the output end. This determines whether there is an abnormality in the scan path.

However, with this method, no matter where on the scan path the fault is, the data retrieved from the output end of the scan path is the same. Therefore, although it is possible to determine whether there is an abnormality in the scan path, there is a drawback that it is not possible to point out the abnormal location on the scan path.

SUMMARY OF THE INVENTION An object of the present invention is to provide a scan path circuit capable of observing the above-mentioned points and pointing out abnormalities on a scan path.

[Means for solving problems]

The scan path circuit of the present invention has a scan path in which flip-flops of a data processing device are connected serially, and code information that can identify this boundary from a boundary divided by hardware units that perform maintenance exchange. an input means for inputting to the scan path; and a counting means connected to the scan path for detecting the code information input to the scan path by the input means from output information of the scan path and counting the number of times of detection. , control means for controlling a shifting operation on the scan path and instructing the input means to input the code information from the boundary of the scan path.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. The main parts of the scan path circuit of this embodiment include a diagnostic processing device 1, a data processing device 2, and an interface 3.

The diagnostic processing device 1 includes a control command register 11, a data sending flip-flop (hereinafter abbreviated as FF) 12,
It is composed of a data receiving FF 13 and a counting means 14.

The data processing device 2 includes a control means 21 and a scan path 2.
2 to 24, and input means 25 to 27.

The diagnostic processing device 1 receives control commands and scan paths 22 that instruct operations necessary for diagnosing the failure of the data processing device 2.
24 are generated and sent to the data processing device 2 via the interface 3. Further, data output from the scan paths 22 to 24 is received from the data processing device 2 via the ink face 3. The generated control command is sent to the control command register 11, and output from the control command register 11 to the interface 2. In addition, the generated data is sent to the data sending FF 12 bit by bit.
is set and output to interface 2. The data from the data processing device 2 is processed by the data reception F for each bit.
F13 is entered, and the output of the data receiving FF13 is used within the diagnostic processing device 1. The counting means 14 detects code information in the output data from the scan paths 22 to 24 and counts the number of times of detection.

FIG. 2 is a circuit diagram showing a specific example of the counting means 14. This counting means 14 includes a comparison data register 141, a shift register 142, and a comparison circuit 14.
3 and a +1 counter 144. The same code information input to the scan paths 22 to 24 is sent to the comparison data register 141. The shift register 142 inputs the output data from the scan paths 22 to 24 while performing a 1-bit shift inside the register, thereby converting the serial data into parallel data having the same focus width as the comparison data register 141.

The comparison circuit 143 performs a bit comparison between the data in the comparison data register 141 and the data in the shift register 142, and outputs an equal signal if all bits are equal. The +1 counter 144 is set to +1 by the equal signal from the comparator circuit 143.
The data in the 1 counter 144 is incremented by 1 and updated.

Further, the +1 counter 144 can clear the contents of the counter 144.

The control means 21 receives control commands and data from the diagnostic processing device 1. The control means 21 decodes the control command, selects the scan paths 22 to 24, shifts the selected scan paths 22 to 24, and controls the selected scan paths 22.
The input means 25 to 24 output a control signal for inputting code information to the input means 25 to 27.

Further, the control means 21 distributes the data from the diagnostic processing device 1 to all of the scan paths 22 to 24, and selects the output information of the scan paths 22 to 24 that are performing the shift operation to the diagnostic processing device 1. Send.

Scan paths 22 to 24 are OFF in the data processing device 2
are connected bit serially, and all FFs on the path are shifted by 1 bit according to the control signal from the control means 21, and this 1-bit shift is repeated to send data to all FFs on the path and from all FFs on the path. Generally, there is a plurality of scan paths in a data processing device for extracting data, and in this embodiment, three scan paths 22 to 24 are set.

The input means 25-27 input into the scan paths 22-24 code information that can identify the boundary between the scan paths 22-24 divided into units of hardware to be maintained and replaced. Instead of generating a fixed code using the input means 25 to 27, data sent from the diagnostic processing device 1 is used as the code information. Therefore, this data is input to the scan paths 22 to 24 from the boundaries divided by hardware units via the input means 25 to 27. Of course, this data is a unique code indicating the boundary, as well as "0" and "1" on the scan paths 22 to 24.
``1'' and ``O'' data must be included in order to detect a fixed failure with . Note that by generating the code information in the diagnostic processing device 1, flexible code setting becomes possible.

The code information is input to the scan paths 22 to 24 in accordance with a 1-bit shift operation performed to confirm the normality of the scan paths 22 to 24. At this time, the FF located at the boundary inputs data from the input means 25 to 27 instead of data from the adjacent OFF across the boundary. When all bits of code information have been input, this FF changes the input to data from the adjacent OFF across the boundary. This control is performed using a control signal from the control means 21. Scan path 22~
The code information input in 24 is scan path 22-2.
4 by repeating the 1-bit shift operation and sent to the diagnostic processing device 1 via the control means 21 and the interface 3.

Figure 3 shows scan paths 22-24 and input means 25-27.
2 is a circuit diagram showing a specific example of the above, and a scan path 22 and an input means 25 are illustrated as representatives of both.

The scan path 22 is configured by serially connecting FFs that receive output information from a logic circuit that implements the functions of the data processing device 2. Each FF has an input terminal into which output information from the logic circuit is input, as well as an input terminal into which output information from other FFs is input. Connect the output end of one FF to the other
The output terminal of the connected FF is further connected to the input terminal of another FF. Repeat this and FF
ga bottle) #f on cereal! Continued scan path 22
is configured.

The input means 25 connects the input data from the diagnostic processing device 1 to one of the FFs located across the boundary, which is the input side of the scan path 22 . This FF is controlled by the control means 21
If the control signal A from the control means 21 is output, the input data from the diagnostic processing device 1 is input, and if the control signal B from the control means 21 is output and the control signal A is not output, the data from the adjacent FF is input. do.

Next, the operation of the scan path circuit of this embodiment configured as described above will be explained.

First, the diagnostic processing device 1 clears the (-l counter 144 in the counting means 14, and the data processing device 2
Compare the same data as the code information sent to data register 1.
Set to 41. Next, the diagnostic processing device 1 sets in the control command register 11 a control command instructing a 1-bit shift operation of the scan path 22 and an input operation of code information. At the same time, the first bit of the code information is set in the data sending FFL2. This control command and 1
The bit data is sent to the control means 21 via the interface 3.

The control means 21 decodes this control command and outputs a control signal for inputting code information into the scan path 22 and a control signal for shifting the scan path 22 by 1 bit. The scan path 22 performs a 1-bit shift operation based on these control Il signals, and inputs the first 1 bit of code information to the FF located at the boundary.

The diagnostic processing device 1 repeats setting the control command and setting the code information until all bits of the code information are input to the scan path 22.

When all bits of code information have been input to the scan path 22, the diagnostic processing device 1 sends a control command to the control command register to instruct a 1-bit shift operation of the scan path 22 until all FF data of the scan path 22 is output. Keep cents on 11.

The control means 21 decodes this control command and outputs a control signal for performing a 1-bit shift operation of the scan path 22. The scan path 22 performs a 1-bit shift operation in response to the control in signal, and sends 1-bit output information to the diagnostic processing device 1 via the control means 21 and the interface 3.

The counting means 14 of the diagnostic processing device 1 takes in 1-bit output information into the shift register 142, performs a bit comparison with the data in the comparison data register 141 in the comparison circuit 143, and detects code information. This operation continues until the output information of all FFs of the scan path 22 is captured and compared. Every time the comparison circuit 143 detects code information, +
1 counter 144 counts and accumulates the number of times code information is detected.

When all the above operations are completed, the +1 counter 144 stores the number of hardware units for which normal maintenance/replacement is performed, counted from the output side of the scan path 22. By knowing the value of this +1 counter 144, the It is possible to confirm the normality of the campus and to know the location on the scan path 22 of each hardware unit that has an abnormal location.

〔Effect of the invention〕

As explained above, the present invention inputs code information indicating this boundary into the scan path from the boundary where the scan path is divided into units of hardware to be maintained and replaced, reads the code information through the scan path, and reads out the code information from the read code information. By measuring the number, it is possible to easily confirm the normality of the scan path and point out the hardware unit that has an abnormality.

In addition, the code information input to each piece of hardware on the scan path is the same, and the hardware This has the effect of easily confirming the normality of the scan path and pointing out hardware with abnormalities without compromising identity.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the counting means shown in FIG. 1, and FIG. 3 is a block diagram showing a specific example of the counting means shown in FIG. FIG. 2 is a circuit diagram showing a specific example of a campus and an input means. In the figure, 1...Diagnostic processing device, 2...Data processing device, 3...Interface, 11...Control command register, 12...Data sending flip-flop, 13...・
- Data reception flip-flop, 14... Counting means, 21... Control means, 22-24... Scan path, 25-27... Input means, 141... Comparison data register, 142...
- Shift register, 143...Comparison circuit, 144...+1 counter.

Claims (1)

[Claims] A scan path in which flip-flops of a data processing device are connected in a bit serial manner, and code information that can identify this boundary from the boundary where this scan path is divided into units of hardware to be maintained and replaced. an input means for inputting; a counting means connected to the scan path and configured to detect the code information inputted to the scan path by the input means from output information of the scan path and count the number of times of detection; a control means for controlling the above shift operation and instructing the input means to input the code information from the boundary of the scan path.