JPH04132092A - Program redundancy device - Google Patents

Abstract

PURPOSE:To shorten production period and to reduce cost by connecting the output of an address coincidence detection circuit to a second program memory for redundancy which can perform writing from the outside and providing an output control circuit where the output of the address coincidence detection circuit and the output of the first and second program memories are connected. CONSTITUTION:When an erroneous program becomes clear after production, an address indicating the program is written in an address memory 5 for redundancy from the external part of an LSI, further, the program where the error is corrected is written in a program memory 6 for redundancy from the external part of the LSI. When the address of a program memory 2 and the address of the address memory 6 for redundancy are detected by a coincidence detection circuit 4 and they are coincident, the program memory 2 is switched to the program memory 6 for redundancy through an output control circuit 3 to be rewritten to a correct program. Thus, the required operation of the LSI can be performed, and immense effect can be expected in correction TAT and in cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a program redundancy device, and particularly to a program memory redundancy system in an LSI with a built-in program memory.

[Conventional technology]

Conventionally, in this type of LSI with built-in program memory,
If there was an error in the program in memory, it was necessary to rebuild the LSI from the manufacturing process.

[Problem to be solved by the invention]

In the conventional LSI with built-in program memory mentioned above,
If there is an error in the program contents of a specific address, L
It was necessary to start over from the process of porting the program software of the SI manufacturing process to memory, which resulted in a long manufacturing period and a large amount of cost.

Furthermore, even if a program memory that can be written to and erased from the outside of the LSI is used, it is necessary to provide a window for erasing on the package, and problems such as package cost and erroneous erasure remain. If you look into it, it was manufactured and sold in a form that cannot be erased.

[Means to solve the problem]

The configuration of the program redundancy device of the present invention is such that the output of an internal first address register is connected to the first program memory, and the output of the address memory for redundancy set from the outside is connected to the output of the first address register. An address output circuit is provided for comparing the output with the output, and the output of the address output circuit is connected to a second program memory for redundancy that can be written from the outside, and the output of the address output circuit and the No. 1. The present invention is characterized in that an output control circuit connected to the output of the second program memory is provided.

〔Example〕

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

FIG. 1 is a block diagram showing a program redundancy device according to an embodiment of the present invention.

In FIG. 1, the program redundancy device of this embodiment has an address register 1 and a program memory 2.
, an output control circuit 3 , an address-loading circuit 4 , a redundancy address memory 5 , and a redundancy program memory 6 .

Output A of address register 1. ~A specifies the program address of the program memory 2, and is further connected to the address-loading circuit 4.

Output RA of address memory 5 for redundancy.

~RA is also connected to the address-loading circuit 4,
When the outputs Ao~A and outputs RA, ~RA, match, the matching address is set as the output AAo~A A I,
It specifies the address of the redundancy program memory 6 and connects the coincidence detection signal to the output control circuit 3.

The redundancy program memory 6 outputs the program at the designated address as an output RRO, .about.RRO, ., and connects it to the output control circuit 3. The outputs RO, ~RO, of the program memory 2 are also connected to the output control circuit 3, and the output ol~01 of the output control circuit 3 is obtained.

Now, write the OF address into the redundancy address memory 5, and write the instruction X into the redundancy program memory 6.
When the address of the address register 1 specifies OF, the address-output circuit 4 detects a match, sends a match detection signal to the output control circuit 3, and the outputs 01 to O1 of the output control circuit 3 are , are the same as the outputs RRO1 to RRO of the redundancy program memory 6,
Execute command X. If the address-layout circuit 4 does not detect a match, the outputs 01 to 01 of the output control circuit 3, which are output by the match detection signal, become the outputs RO, to RO of the program memory 2, and redundancy is not performed. In order to solve this problem, the program redundancy device of this embodiment writes an address pointing to the program into the redundancy address memory 5 from outside the LSI when an erroneous program is found after manufacturing.
Furthermore, a program with corrected errors is written from outside the LSI to the redundancy program memory 6, and the match detection circuit 4 detects the address of the program memory 2 and the address of the redundancy address memory 6. If they match, the program memory 2 is written for redundancy. The program memory 6 is switched to the correct program using the output control circuit 3.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to cause a program with an error or a program to be changed to operate as desired by simply writing only the address setting and replacement program from outside the LSI. It has great effects in terms of cost and cost.

Another advantage of the present invention is that the memory capacity of the redundancy program memory can be changed as needed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a program redundancy device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Address register, 2...Program memory, 3...Output control circuit, 4...Address match detection circuit, 5...Address memory for redundancy, program memory for redundancy. 6...

Claims (1)

[Claims] An address match detection circuit is provided which connects the output of an internal first address register to a first program memory and compares the output of the redundancy address memory set from the outside with the output of the first address register. , an output control in which the output of the address match detection circuit is connected to a second program memory for redundancy that can be written from the outside, and the output of the address match detection circuit is connected to the outputs of the first and second program memories. A program redundancy device characterized by having a circuit.