JP2012113587A - Digital device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a memory error of 2 bit or more due to power-off by allowing the memory to surely store all bits of write data on data bus, even if a power is shut down during a writing operation to the memory.SOLUTION: The digital device includes: as power receiving side circuits, memory means for storing data, memory control means for writing and reading with respect to the memory means, and ECC means for correcting and detecting a bit error of the memory means; and, as power supply side circuits, monitoring means for detecting the shutdown of a main power supply and giving a reset signal, and power switching means, even if the main power supply is shut down, switching it to a backup auxiliary power supply to supply the power to the memory means. The reset operations of the memory means, the memory control means and the ECC means by the reset signal of the monitoring means are performed after finishing the writing of the memory means.

Description

  The present invention relates to a digital device, and more particularly to a digital device capable of stably performing a memory write operation even when the power is turned off.

  As a digital device, for example, a digital protection control device is provided with a data saving function as a standard, and by using operation information of the digital protection control device periodically stored in a memory, failure location analysis and relay device response are performed. Used for maintenance support such as analysis. As a data saving memory, an SRAM with less restrictions on writing time and capacity is generally used as a power backup, but a non-volatile memory such as a flash memory may be used.

  As a memory in such a digital protection control device, it is desirable to have an ECC (Error Checking and Collecting) function for detecting a 1-bit error and detecting an error of 2 or more bits in order to ensure data reliability.

  The ECC function is described in Non-Patent Document 1. In Non-Patent Document 1, the memory used for the data saving function is an SRAM that is backed up or used so that the operation information of the digital protection control device does not disappear due to power shutdown, or a non-volatile memory is used. It has been shown to have an ECC function to ensure reliability.

"Electrical Cooperative Research" Vol. 65, No. 2

  However, if the power is cut off during the write operation to the memory, data that could or cannot be written for each bit due to variations in the setup time of each bit on the data bus is stored in the memory. As a result, when the power is turned on again, an error of 2 bits or more is detected by the ECC function, which is handled as a memory failure and the memory data is initialized (cleared).

  As a result, the operation information of the past digital protection control device stored in the memory by the data saving function disappears, and there is a problem that maintenance support such as failure site analysis and relay device response analysis cannot be performed.

  The present invention provides a digital memory capable of reliably storing all the bits of write data on the data bus in the memory even when the power is cut off during a write operation to the memory, thereby preventing an error of two or more bits of the memory due to the power interruption. Providing equipment.

  The digital device of the present invention comprises memory means for storing data as a power receiving side circuit, memory control means for writing and reading data to the memory means, and ECC means for correcting and detecting bit errors in the memory means, The power supply side circuit has a monitoring means for detecting a main power supply interruption and giving a reset signal, and a power supply switching means for switching to a backup auxiliary power supply to supply power even when the main power supply to the memory means is cut off. The reset operation of the memory means, the memory control means, and the ECC means by the reset signal is performed after the writing of the memory means is completed.

  The memory control means sets the memory means to the standby state after the write is completed.

  A digital device according to the present invention includes a memory means for storing data as a power receiving side circuit, a CPU for instructing the memory means to write and read, and a memory for performing writing and reading to the memory means in accordance with instructions from the CPU The control means and the ECC means for correcting and detecting the bit error of the memory means are provided. The power supply side circuit detects a main power supply cut-off and gives a reset signal. And a power supply switching means for switching to the backup auxiliary power supply and supplying the power. The write access signal is generated from the start of the write to the memory means after the write access is instructed by the CPU, and the monitoring means An emphasis reset signal is created by the logical sum signal of the reset signal and write status signal to be applied, and the emphasis reset signal Executing a reset operation of the memory means and memory control means and the ECC means.

  The digital device is a protective relay device that inputs an electric quantity of the power system, detects an accident, and operates a circuit breaker provided in the power system.

  According to the present invention, even if the power is cut off during a write operation to the memory, all the write data bits on the data bus are surely stored in the memory to prevent an error of two or more bits of the memory due to the power cut. it can.

The control circuit block diagram of a digital protection relay device. The block diagram of a power supply corresponding memory control part. The flowchart which shows the SRAM access timing which considered power supply cooperation.

  FIG. 1 shows a configuration diagram of a control circuit of a digital protection relay device as an example of a digital device according to the present invention. This digital protection relay device is roughly composed of a power supply side circuit portion 140 and a power reception side circuit portion 130. Among these, the power supply side circuit portion 140 includes the main power supply 10, the power switch 20, the backup capacitor 30, the power supply monitoring unit 40, the backup power supply switching circuit 50, and the like. The power receiving side circuit portion 130 includes a CPU 60, a system bus 70, an SRAM 80, a power supply coordination compatible memory control unit 90, a communication unit 100, an analog input unit 110, and an input / output unit 120.

  The power supply side circuit portion 140 functions as follows. The main power supply 10 outputs a constant power supply 5V, for example, and the power switch 20 switches on / off the power supply 5V from the main power supply 10. The backup capacitor 30 is charged when the 5V power is turned on, and supplies the backup power to the SRAM 80 when the 5V power is cut off. The power supply monitoring unit 40 detects a power supply voltage drop due to a power supply switch 20 shutoff or an insufficient voltage abnormality of the main power supply 10, outputs a switching signal to the backup power supply switching circuit 50, and operates on a 5 V power supply voltage. A reset signal is output to 130. When receiving the switching signal from the power supply monitoring unit 40, the backup power supply switching circuit 50 switches the power supply to the SRAM 80 to the backup capacitor 30 side.

  The power receiving side circuit portion 130 functions as follows. First, the analog input unit 110 converts the current and voltage taken from the power system into an analog voltage signal of ± 10 V or less, and converts it into digital data by A / D conversion. The CPU 60 takes the data converted into digital data by the analog input unit 110 via the system bus 70, executes digital filter processing for removing the harmonic signal superimposed on the signal of the power system, and protection calculation / sequence processing, Input / output control is performed on the input / output unit 120 via the system bus 70 from the processing result.

  The data converted into digital data by the analog input unit 110, the digital filter process, and the protection calculation / sequence process result are stored in the SRAM 80 from the CPU 60 via the system bus 70 as data save information. In order to increase the reliability of the SRAM 80, an SRAM power supply cooperative correspondence memory control unit 90 having a 1-bit error correction function and an error detection function of 2 bits or more is provided.

  In the digital device of the present invention, the stored information in the SRAM 80 is also provided when the power supply side circuit portion 140 has an abnormality in the power supply (power supply switch 20 is cut off or the power supply voltage is lowered due to an abnormal undervoltage of the main power supply 10). The SRAM power supply cooperative memory control unit 90 is caused to function so as to correctly hold the signal.

  FIG. 2 shows a specific circuit configuration of the SRAM power supply cooperative compatible memory control unit 90. The SRAM power supply coordination compatible memory control unit 90 is externally linked to the power supply monitoring unit 40, the CPU 60, and the SRAM 80, and internally includes a power supply coordination reset circuit 91, an access control unit 92, and an ECC data processing unit 93. Yes.

  Among these, the access control unit 92 identifies whether this access is to the SRAM 80 from the chip select (CS) signal and the address (A) signal input from the CPU 60. Further, read / write of the access type for the SRAM 80 is identified from the read (RD) signal and the write enable (WE) signal.

  If the access input from the CPU 60 is a read / write access to the SRAM 80, a chip select (S_CS), address (S_A), write enable (S_WE), and read output enable (S_OE) signal are output to the SRAM 80. To do.

  Further, a write state signal 921 indicating that a write access to the SRAM 80 is being performed is output to the power supply cooperative reset circuit 91, and the ECC signal processing unit 93 receives a data signal (D) that is a bidirectional bus from the write / read identification result. And the WR signal 922 which determines the direction of (S_D) is output.

  Next, the ECC data processing unit 93 switches the write / read ECC data processing according to the WR signal 922 from the access control unit 92.

  That is, at the time of writing, 16-bit write data is input from the D signal to the ECC data processing unit 93 from the CPU 60, so that 6-bit ECC check data is created from the 16-bit write data. Then, a total of 22-bit write data obtained by adding 6-bit ECC check data to 16-bit write data is obtained and output to the SRAM 80 using the S_D signal. In the SRAM 80, this data is written into a designated address (S_A).

  At the time of reading, a total 22-bit S_D signal composed of 16-bit read data and 6-bit ECC check data is input from the SRAM 80 to the ECC data processing unit 93. ECC check data is generated again for the input 16-bit read data, and compared with the 6-bit ECC check data input from the SRAM 80, a 1-bit error and an error of 2 bits or more are detected.

As a result, if there is no error, 16-bit read data is output to the CPU 60.
When a 1-bit error is detected, the 1-bit error is corrected by inverting the erroneous bit of the 16-bit data, and the corrected 16-bit data is output to the CPU 60 and the SRAM 80.

  On the other hand, when an error of 2 bits or more is detected, error correction cannot be performed. Therefore, in this case, the CPU 60 is notified of an error detection of 2 bits or more by an interrupt (IRQ) signal. When the CPU 60 receives notification of error detection of 2 bits or more, it executes countermeasures for abnormality such as initialization processing of the SRAM 80.

  Finally, when the reset signal 40R is input from the power monitoring unit 40 when the power is shut down, the power cooperative reset circuit 91 ends the write access if the write state signal 921 of the access control unit 92 indicates write access. Until this time, the process of waiting for the output of the cooperative reset signal 911 and the standby signal 912 is executed. As a result, even if the power is cut off in the write state, the cooperative reset and standby processing are not executed until the write access is completed.

  FIG. 3 shows the SRAM write access timing when the power interruption occurs in the write state.

  Conventionally, when the power is cut off during the write access, an SRAM control signal (standby 912, chip select (S_CS), address (S_A), write enable (S_WE), All the write data (S_D) has been reset.

  For this reason, the setup time of the write data (S_D) of the SRAM 80 is insufficient, and variations in whether or not data can be written for each bit occur due to the influence of variations in the data signal line delay for each bit.

  As a result, this becomes an error detection of 2 bits or more by the ECC function when the power is turned on again, which is regarded as a memory abnormality in the digital protection relay system, and an abnormality countermeasure such as a memory initialization process is executed. As a result, the operation information of the past digital protection control device stored in the memory by the data saving function disappears, and there is a problem that maintenance support such as failure site analysis and relay device response analysis cannot be performed.

  In the present invention, the reset signal 40R and the write state signal are supplied from the power supply monitoring unit 40 to reset the SRAM control signals (standby 912, chip select (S_CS), address (S_A), write enable (S_WE), write data (S_D)). Since the cooperative reset signal 911 obtained by ORing 921 is used, the reset of the SRAM control signal can be kept waiting until the end of the write access even if the power is cut off during the write.

  As a result, the write data (S_D) of the SRAM 80 can secure a sufficient setup time, and therefore is not affected by the signal delay variation of each bit, so there is no write variation for each bit.

  As a result, even if the power is cut off during the write operation to the memory, all bits of the write data on the data bus can be reliably stored in the memory, so that an error of 2 bits or more due to the power interruption can be prevented.

10: Main power supply 20: Power switch 30: Backup capacitor 40: Power supply monitoring unit 50: Backup power supply switching circuit 60: CPU
70: System bus 80: SRAM
90: Power supply cooperative memory control unit 100: Communication unit 110: Analog input unit 120: Input / output unit 91: Power supply cooperative reset circuit 92: Access control unit 93: ECC data processing unit 40R: Reset signal 921: Write state signal 911 Coordinated reset signal

Claims (4)

As a power supply side circuit, there is provided a memory means for storing data as a power receiving side circuit, a memory control means for writing to and reading from the memory means, and an ECC means for correcting and detecting a bit error of the memory means. In a digital apparatus having monitoring means for detecting a main power supply cutoff and giving a reset signal, and a power supply switching means for switching to a backup auxiliary power supply and supplying power even when the main power supply is cut off to the memory means,
The digital device according to claim 1, wherein the reset operation of the memory means, the memory control means, and the ECC means by the reset signal of the monitoring means is performed after the writing of the memory means is completed. In the digital device according to claim 1,
The digital protection relay device, wherein the memory control means puts the memory means into a standby state after writing is completed. Memory means for storing data as a power receiving side circuit; a CPU for instructing writing and reading to the memory means; and a memory control means for writing to and reading from the memory means in accordance with instructions from the CPU; ECC means for correcting and detecting a bit error of the memory means, a monitoring means for detecting a main power supply interruption and providing a reset signal as a power supply side circuit, and a backup even if the main power supply is cut off to the memory means In a digital apparatus having power supply switching means for supplying power by switching to an auxiliary power supply,
A write status signal is generated during a period from the start of writing to the memory means when a write access is instructed by the CPU to the end of the memory means, and an emphasis reset by a logical sum signal of the reset signal and the write status signal given by the monitoring means A digital apparatus for generating a signal and performing a reset operation of the memory means, the memory control means, and the ECC means by the emphasis reset signal. In the digital device according to any one of Items 1 to 3,
The digital device is a protective relay device that inputs a quantity of electricity of a power system, detects an accident, and operates a circuit breaker provided in the power system.

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