JPH0934801A - Method for detecting pointer control abnormality for fifo - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a print control defect by checking data as to whether or not the data are out of an FIFO in the order of being written so as to check an abnormality of a pointer control function of the FIFO including parity data. SOLUTION: A FIFO(First In First Out) is reset. Check data to write the FIFO are reset. The check data are written in the FIFO. The check data are incremented. The processing above is repeated by a capacity of data to be checked. Then the check data are reset to make comparison check of the data in the FIFO. Data in the FIFO are read. The data in the FIFO and the check data are verified for checking. When verification error is caused in the data of the FIFO, error processing is executed to stop the processing. Then the check data are incremented. The processing above is repeated by a capacity of data to be checked. The FIFO is reset.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of expandable FIFOs (First In Firs) accessed by a microprocessor.
t Out) or a method of checking the FIFO unit. The FIFO unit is a FIFO chip, a FIFO module, or a plurality of Fs that are expansion units.
It means one composed of IFOs.

[0002]

2. Description of the Related Art In a conventional FIFO check, the same data is written in all areas of the memory section of the FIFO, and after this write operation is completed, the data is read from the memory section of the FIFO and the written data is only verified. It was

[0003]

When an error occurs in the pointer control function of the FIFO, the data to be checked (including the parity data) is the same in all areas,
It was not possible to check whether the data written in the IFO was read out in the order written.

An object of the present invention is to eliminate defective print control due to defective operation of the FIFO.

[0005]

The above object is achieved by checking whether the data written in the FIFO are read out in the order in which they were written, and by checking the abnormality of the pointer control function of the FIFO including the parity data.

[0006]

[Function] The pointer control function of the FIFO is normal by changing the data to be written to the FIFO for each byte and writing the data, and checking the data read from the FIFO for each byte as well as the check data changed in the same manner as at the time of writing. Check if it can work.

[0007]

An embodiment of the present invention will be described below. In the present invention, the check is performed by the following steps. (1) Reset the FIFO. (2) Reset the check data written to the FIFO.

(3) Write check data in the FIFO. (4) Increment the check data. (5) Repeat the above (3) and (4) for the capacity to be checked. (6) Reset the check data to compare and check the FIFO data. (7) Read the FIFO data. (8) Verify the FIFO data and check data. (9) If the FIFO data has a verify error, error processing is performed and the processing is stopped. (10) Increment the check data. (11) Repeat steps (7) to (10) for the capacity to be checked. (12) Reset the FIFO.

[0009]

According to the present invention, the FIFO first in
Print control failure can be eliminated by detecting the first out function at power-on.

[Brief description of drawings]

FIG. 1 is a flowchart of the present invention.

FIG. 2 is an explanatory diagram showing a case where a FIFO pointer control is normal.

FIG. 3 is an explanatory diagram showing a case where the FIFO pointer control is abnormal.

[Explanation of symbols]

 VCKDT ... Data for checking FIFO

Claims (1)

[Claims] 1. A method for detecting an abnormality in a pointer control of a FIFO, comprising checking whether the data written in the FIFO is read out in the order of writing, and checking the abnormality of the pointer control function of the FIFO including parity data.