Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F11/00—Error detection; Error correction; Monitoring
  • G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
  • G06F11/08—Error detection or correction by redundancy in data representation, e.g. by using checking codes
  • G06F11/10—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
  • G06F11/1008—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's in individual solid state devices
  • G06F11/1012—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's in individual solid state devices using codes or arrangements adapted for a specific type of error
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F11/00—Error detection; Error correction; Monitoring
  • G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
  • G06F11/08—Error detection or correction by redundancy in data representation, e.g. by using checking codes
  • G06F11/10—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
  • G06F11/1008—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's in individual solid state devices
  • G06F11/1068—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's in individual solid state devices in sector programmable memories, e.g. flash disk
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F11/00—Error detection; Error correction; Monitoring
  • G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
  • G06F11/08—Error detection or correction by redundancy in data representation, e.g. by using checking codes
  • G06F11/10—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
  • G06F11/1008—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's in individual solid state devices
  • G06F11/1048—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's in individual solid state devices using arrangements adapted for a specific error detection or correction feature
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
  • G06F3/0601—Interfaces specially adapted for storage systems
  • G06F3/0602—Interfaces specially adapted for storage systems specifically adapted to achieve a particular effect
  • G06F3/0614—Improving the reliability of storage systems
  • G06F3/0619—Improving the reliability of storage systems in relation to data integrity, e.g. data losses, bit errors
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
  • G06F3/0601—Interfaces specially adapted for storage systems
  • G06F3/0628—Interfaces specially adapted for storage systems making use of a particular technique
  • G06F3/0638—Organizing or formatting or addressing of data
  • G06F3/064—Management of blocks
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
  • G06F3/0601—Interfaces specially adapted for storage systems
  • G06F3/0668—Interfaces specially adapted for storage systems adopting a particular infrastructure
  • G06F3/0671—In-line storage system
  • G06F3/0673—Single storage device
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11C—STATIC STORES
  • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
  • G11C29/52—Protection of memory contents; Detection of errors in memory contents

Definitions

• ECCs error correction codes
• ECC memory is a type of computer data storage that can detect and correct most conventional types of internal data corruption.
• ECC memory circuits may be used in computers where data corruption cannot generally be tolerated, such as for scientific or for automotive memories for safety critical advanced driver assistance systems (ADAS) which need to comply with functional safety requirements.
• ADAS safety critical advanced driver assistance systems
• ECC Error Correction Code
• generate ECC hardware units are provided in the write path and in the read path, with a generate ECC unit in the write path, and with a check ECC block including another generate ECC unit in the read path.
• the write path circuitry and read path circuitry have no cross coupling connections and thus operate independently from one another.
• the ECC is re-recomputed by the check ECC block which is compared with the stored ECC by an XOR circuit.
• the result (output) of this XOR circuit is called the syndrome. If the syndrome is zero, no error has occurred.
• the syndrome can be used to index a table to a "Syndrome decode" to determine which bits are in error in case of a single bit error correction (SEC), or that the error is uncorrectable in case of a double bit error detection (DED). Accordingly, conventional ECC memory can generally maintain a memory system effectively free from most bit errors.
• SEC single bit error correction
• DED double bit error detection
• lockstep ECC circuit hardware comprises an error correction circuit that uses cross-coupled connections between the write path circuitry and read path circuitry, which enables the reuse of ECC generation logic on one side of the memory circuit to check for errors on the other side, thus reducing the ECC logic requirement and saving significant semiconductor chip area.
• Described examples include a method of fault detection for ECC circuitry for a memory circuit having write generation (Gen) ECC logic in a write path circuitry and check ECC logic including read Gen ECC logic in read path circuitry. An output of the read Gen ECC logic and an output of the write Gen ECC logic are compared by a digital comparator to check whether the respective bits strings match.
• a fault in the write Gen ECC logic or in the read Gen ECC logic is detected when the bits strings do not match.
• the write operation can be repeated.
• the single bit errors can be corrected, and a multi-bit error interrupt signal can be sent.
• FIG. 1 is a block diagram of an example ECC memory circuit having described lockstep ECC circuit hardware for fault detection in the read side ECC logic having a multiplexer with a first input for receiving write data in series with an input to the ECC generation logic, according to an example embodiment.
• Write data is selected during a normal write operation, and read data is selected during the read operation.
• FIG. 2 is a block diagram of another example ECC memory circuit having described lockstep ECC circuit hardware for fault detection in write side ECC logic having a multiplexer with a first input for receiving the read data from the memory circuit in series with an input of the Gen ECC logic for fault detection in the ECC logic, according to an example embodiment.
• FIG. 3 is a flow chart that shows steps in an example method of fault detection for ECC circuitry, according to an example embodiment.
• FIG. 4 is example ECC memory circuit including described ECC hardware for fault detection in its read path and write path that essentially combines the read side and write side error checking embodiments described hereinabove relative to FIG. 1 and FIG. 2, according to an example embodiment.
• FIG. 5 is a system diagram of an example ADAS system including two instances of the described ECC memory circuit shown in FIG. 4 as processor memory having described lockstep ECC circuit hardware for fault detection in the ECC logic in its read path and write path, according to an example embodiment.
• Coupled to or “couples with” (and the like) describe either an indirect or direct electrical connection.
• a first device “couples” to a second device, that connection can be through a direct electrical connection where only parasitics are in the pathway, or through an indirect electrical connection via intervening items including other devices and connections.
• the intervening item generally does not modify the information of a signal, but may adjust its current level, voltage level and/or power level.
• transient or permanent errors can exist in the write side, which can result in wrong ECC bits being written into the memory during the write operation.
• Transient or permanent errors in the ECC logic hardware in the read side of ECC memory circuits can result in corruption of memory read data or in the wrong flagging of memory read data as corrupted when the read data is in fact not corrupted. If write path circuitry and read path circuitry operate independently, then detection of transient/permanent errors in the ECC logic of ECC memory circuits may be possible, but implementation of such detection would require significant additional logic, including extra ECC generation logic on both sides of the ECC memory circuit.
• FIG. 1 shows an ECC memory circuit 100 including a memory circuit 130 (e.g., SRAM, ROM, or a flash memory chip) and described "lockstep" ECC hardware 110 having fault detection in its ECC logic circuitry configured for verifying the bit output of the read path Gen ECC 120bi in the read path circuitry 120.
• the memory circuit 130 comprises a single port memory where only one operation (read or write) can be performed for a given clock pulse. This single port memory feature enables the bit output from one of the ECC GEN logics (the side that is not active at the particular time/clock, write not being active as shown in FIG. 1, and read not being active as shown in FIG. 2) to be available as a reference to enable described lockstep error detection.
• the memory circuit 130 includes a common substrate 105 having at least a semiconductor surface.
• the substrate 105 can comprise a bulk silicon substrate, or an epitaxial layer on a bulk silicon substrate.
• the memory circuit 130 has a separate data output and a separate ECC output. Data shown as k bits is stored along with ECC bits shown as r bits. For example, if a non-ECC memory stores 64 bits of data, then an ECC memory will store the same 64 bits of data with an extra 8 bits of ECC. Hence 64+8 bits are written and 64+8 bits are read out. The ECC 8 bits are used to validate the 64 data bits, and goes to the XOR logic in the Check ECC.
• Write path circuitry 115 includes write Generation (Gen) ECC logic 115b, and check ECC logic 120b includes read Gen ECC logic 120bi in the read path circuitry 120. While operating in the write mode (write mode is active in FIG. 2 described hereinbelow), data bits (shown as WR data, such as 64 bits) and the corresponding computed ECC bits (such as 8 bits) from the write ECC Gen logic 115b are each written into the memory circuit 100 in the same clock cycle.
• the data width for the memory circuit 130 can in one example be 72 bits (72 bit wide memory) including 64 bits (data) +8 bits (ECC), which can be realized as two separate memories of width 64 and width 8, or be a single 72 bit wide memory.
• ECC bits 64 information/data bits and 8 ECC bits are only examples.
• the actual number of ECC bits can be based on the corresponding bit width for data (information), such as given in the following example:
• a multiplexer (Mux) 115a is provided at the input of write GEN ECC logic 115b to multiplex in cross-coupled read data provided by cross-coupled connection 150 shown as k bits from the memory circuit 130 with the write (wr) data generally from a processor.
• the processor can comprise a microprocessor, digital signal processor (DSP), or a microcontroller unit (MCU).
• the Mux 115a is shown having a select line that is shown based on the memory circuit 130 being in the read mode from a processor which is used to select which of the input lines comprising the rd data from the memory on one line and the wr data on the other line to send to the Mux's 115a output. When in the read mode, the rd data is selected by Mux 115a, while when in the write mode, the wr data is selected.
• a digital comparator 135 is coupled to receive at one input the output from write Gen ECC logic 115b (as a reference as it is inactive during reading) and at its other output the output of the read path Gen ECC 120bi. Digital comparator 135 thus reuses the output from write Gen ECC logic 115b for verifying the bit output of the read path Gen ECC 120bl, both shown only as an example as being 8 bits.
• Read Gen ECC 120b 1 together with an XOR circuit 120b2 constitute the check ECC block 120b. The output of the XOR circuit 120b2 provides "syndrome" signal to the syndrome decode block 120c. If the syndrome is zero, no error has occurred.
• the syndrome decode block 120c determines which bits are in error (SEC), or that the error is uncorrectable (e.g., the error is a double bit error). Single bit errors are provided to the SEC block 120d, which outputs corrected read data shown as rd data.
• the output of the digital comparator 135 is connected as an enable to the multi-bit (2 or more) error interrupt generation and as an enable to the SEC block 120d.
• SEC of memory read data by SEC block 120d and multi-bit error flagging using the syndrome computation provided by syndrome decode 120c are both enabled by the enable signal from the digital comparator 135 if and only if the ECC computations in the write path and the ECC computations in the read path match one another (shown in FIG. 1 as the same r bits).
• FIG. 2 shows an example ECC memory circuit 200 including described ECC hardware 110' for fault detection in its write path including write Gen ECC logic 115b, where a MUX 120e is added in the read path circuitry 120' and a cross-coupled connection 150' is added from the write path circuitry 115' to the MUX 120e in the read path circuitry 120' to mux the write data to data read from the memory circuitl30.
• the described lockstep ECC hardware 110 having fault detection in its ECC logic circuitry is configured for verifying the bit output of the write Gen ECC logic 115b while the write mode is active.
• a control input shown as a "memory write" is the control signal which controls the MUX's 120e input selection node. When in the write mode, the wr data is selected by MUX 120e, while when in the read mode, the rd data is selected.
• ECC bits output by the read Gen ECC logic 120b 1 is used to verify operation of the write Gen ECC logic 115b by digital comparator 135 which compares the ECC bits generated by the respective Gen ECC logics 115b and 120bi.
• the output of the digital comparator 135 that is generated is used as an interrupt to a processor (e.g., a microprocessor, digital signal processor (DSP), or a microcontroller unit (MCU)) to repeat the write transaction.
• a processor e.g., a microprocessor, digital signal processor (DSP), or a microcontroller unit (MCU)
• DSP digital signal processor
• MCU microcontroller unit
• the digital comparator 135 will again keep generating an error in which case the processor can take appropriate action such as indicating to the application software that a permanent fault has occurred in the system. This same fault response is true in case of a read operation also.
• FIG. 3 is a flow chart that shows steps in an example method 300 of fault detection for ECC circuitry associated with a single port memory circuit, according to an example embodiment.
• Step 301 comprises comparing an output of read Gen ECC logic (120bi in FIG. 1 and FIG. 2) to an output of a write Gen ECC logic (115b in FIG. 1 and FIG. 2).
• Step 302 comprises detecting a fault in the write Gen ECC logic or in the read Gen ECC logic when a comparison output from the comparing determines a value of the output of the write Gen ECC logic does not equal a value of the output of the read Gen ECC logic 120bi.
• Step 103 comprises when the fault is a single-bit error during a read operation, correcting the single-bit error, and when the fault is a multi-bit error during a read operation, sending a multi-bit error interrupt signal.
• the fault is an error during a write operation, repeating the writing.
• single bit errors are provided to the SEC block 120d, which outputs corrected read data shown as rd data.
• the write operation can be repeated to ensure that the data written into the memory chip is not in error.
• FIG. 1 write side error checking
• FIG. 2 read side error checking
• FIG. 1 write side error checking
• FIG. 2 read side error checking
• the read side and write side error checking embodiments described hereinabove relative to FIG. 1 and FIG. 2 may be combined together to enable error checking on both sides of the memory circuit 130.
• FIG. 4 is example ECC memory circuit 400 including described ECC hardware 110" for fault detection in both its read path and write path that essentially combines the read side and write side error checking embodiments described hereinabove relative to FIG. 1 and FIG. 2.
• Mux 115a ECC memory circuit 400 includes a second Mux 120e having a first input for receiving read data from the memory circuit 400 in series with an input of the read Gen ECC logic 120b 1 and a cross-coupled connection 150' for coupling the write data to the second input of the second MUX 120e.
• the digital comparator 135 is involved in both read side error checking and write side error checking.
• ECC memory circuits described herein In contrast to ECC memory circuits described herein, conventional ECC logic is used only to detect and correct internal memory (e.g., RAM) errors.
• internal memory e.g., RAM
• fault detection in the ECC logic is achieved in addition to detection and correction of internal memory errors, where any transient/permanent errors in the ECC computation and generation logic are also detected, which enables corrective action to be taken.
• the single bit error can be corrected and a multi-bit error interrupt signal can be generated.
• a lockstep logic in error in the write Gen ECC logic 115b see FIG. 2
• the write operation is repeated.
• described lockstep ECC circuit hardware is non-intrusive and can operate continuously (on every clock cycle, on-the fly) for checking memory ECC logic with only a limited area penalty in terms of additional Muxs and comparators.
• FIG. 5 is a system diagram of an example ADAS system 500 including two instances of the described ECC memory circuit shown in FIG. 4 shown as 400 1 and 400 2 including processor memory 130i (shown as processor memory 1) and 130 2 (shown as processor memory N).
• the ECC memory circuits have described lockstep ECC circuit hardware shown as ECC logic l lOi and 110 2 for fault detection in the read path and write path of the processor memory.
• An image sensor 505 e.g. a CMOS color camera
• the image data is coupled to an image recognition system 515 by a camera interface 510.
• Image recognition system 515 is shown including a video recognition processor 515a, flash memory 515b, external DDR memory 515c, and a controller area network (CAN) bus Tx/Rx (transceiver) 515d.
• CAN controller area network
• the image recognition system 515 is coupled by a CAN bus 520 to the processor block 530 that includes a processor core 530a.
• Processor core 530a is shown coupled by a bus interface 535 to use the processor memory 130i and 130 2 of ECC memory circuits 4001 and 400 2 .
• ECC memory circuits 400i and 400 2 use described lockstep ECC circuit hardware with cross-coupled connections between the write path circuitry and read path circuitry, which enables the reuse of ECC generation logic on one side of the processor memory to check for errors on the other side, and which reduces the ECC logic requirement and saves significant semiconductor chip area.

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