ELECTRONIC DEVICE AND ELECTRONIC DEVICE SYSTEM

Technical Field

The present invention relates to an electronic device using, for example, a flash memory, and to an electronic device system in which the electronic device is embedded. Background Art

Memory systems, for example, memory cards using nonvolatile semiconductor memories such as flash memories, have been used as recording media of music data and video data. As the flash memory used in the memory system, there is known a NAND flash memory, for example. In addition, as the memory system, there is known an SD™ card, for example (see, e.g. Jpn. Pat. Appln. KOKAI Publication No. 2006-92019) .

The memory system is connected to a host apparatus, and data is transmitted/received between the memory system and the host apparatus. An SD interface is known as an interface between the memory system and the host apparatus. The SD interface is an interface with the host apparatus which supports an SD device such as an SD™ card.

In an SD interface bus, a plurality of signal lines, for example, a clock line, a command line and a data line, are defined. These lines are treated as a single bus.

In recent years, host apparatuses, which use a flash memory as a nonvolatile memory device, without having a hard disk drive, have been manufactured. Such a host apparatus needs to read from the flash memory a program code (boot code) which is necessary for booting up the system. Specifically, the boot code is stored in the SD device which is composed of a flash memory, and the boot code is transferred to the system memory via the host controller and is executed.

The boot code is first read after the host apparatus is powered on. Specifically, when the system is powered on, a boot loader, which is stored in a system ROM, is activated by the CPU. The host controller is configured to read the boot code, which is stored in the SD device, according to the boot loader, and to transfer the boot code to the system memory. Thus, the system requires the system ROM for storing the boot loader, and this leads to an increase in manufacturing cost for the system. Therefore, there has been a demand for an electronic device system which requires no system ROM.

Disclosure of Invention According to a first aspect of the invention, there is provided an electronic device system comprising: a processor configured to issue, when power is turned on, an instruction which instructs read of boot information; and a first controller including a command terminal for outputting a command to an electronic device and a plurality of data terminals for transmitting/receiving data to/from the electronic device, the first controller being configured to issue a command for reading the boot information in accordance with the instruction from the processor, to deliver the command from the command terminal to the electronic device, to issue a signal in accordance with a period of issuance of the command, and to supply the signal from one of the data terminals to the electronic device .

According to a second aspect of the invention, there is provided an electronic device comprising: a memory storing boot information; a command terminal configured to receive a command; a plurality of data terminals configured to transmit/receive data; and a controller configured to read the boot information from the memory, upon receiving as a boot information read request a command for reading the boot information, which is delivered to the command terminal when power is turned on, and a signal which is delivered to one of the plurality of data terminals in accordance with a period of issuance of the command, the controller outputting the boot information from the data terminals . Brief Description of Drawings

FIG. 1 schematically shows the structure of a host apparatus and an electronic device according to an embodiment of the invention; FIG. 2 schematically shows a memory map of the electronic device;

FIG. 3 is a timing chart showing an example of a quick boot operation according to the embodiment;

FIG. 4 is a flow chart illustrating an access operation of a boot code area; and

FIG. 5 shows an example of application of the embodiment .

Best Mode for Carrying Out the Invention An embodiment of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 schematically shows the structure of a device according to a first embodiment of the invention, and the structure of a host apparatus in which this device is embedded. The host apparatus 1 includes, for example, a central processing unit (CPU) 2 functional as a processor, a host controller 3 and a system memory 4.

The CPU 2 executes overall control of the host apparatus 1, and operates according to a program, etc. stored in a read-only memory (ROM) (not shown) . The system memory 4 is used for storing an executable program, which is necessary for the operation of the CPU 2, and various data.

The host controller 3 includes, for example, a host interface (I/F) 31, a dynamic memory access (DMA) controller 32, a buffer 33 and an SD interface 34. The host I/F 31 is connected to the CPU 2 and system memory 4, and is also connected to the DMA controller 32 and buffer 33. The buffer 33 is connected to the SD I/F 34.

The host controller 3 is configured to be communicable with, for example, an SD device 5 which is composed of, e.g. a flash memory. Specifically, the host I/F 31 is configured to be communicable with the CPU 2 and system memory 4, and the SD I/F 34 is configured to be communicable with the SD device 5. In addition, the host I/F 31 transfers data, which is delivered from the system memory 4, to the buffer

33, and transfers data, which is read out of the SD device 5 and is held in the buffer 33 via the SD I/F

34, to the system memory 4. The SD I/F 34 transfers data, which is delivered from the system memory 4 via the buffer 33, to the SD device 5, and receives data, which is read from the SD device 5, and delivers the received data to the buffer 33. For example, according to instructions of the CPU

2, the DMA controller 32 controls the host I/F 31, SD I/F 34 and buffer 33, and controls data transfer from the system memory 4 to the SD device 5 and data transfer from the SD device 5 to the system memory 4.

The SD I/F 34 is connected to the SD device 5, for example, via a 1-bit clock line, a command line, and a 4-bit data line. At the time of signal reception, the SD I/F 34 takes in a command SDCMD on the command line and data SDDAT on the data line, the rising edge of a clock signal SDCLK on the clock line. At the time of signal transmission, the SD I/F 34 outputs a command SDCMD, a response and data SDDAT to the command line and data line, on the rising edge or falling edge of the clock signal SDCLK on the clock line. The data line can transfer data in parallel with four bits, or in series with one bit. Specifically, the SD I/F 34 includes a command

(CMD) generator 35 and a data (DAT) generator 36. The CMD generator 35 generates, for example, according to an instruction of the CPU 2, various commands for controlling the SD device 5, and delivers the commands to the SD device 5. The DAT generator 36 generates a signal according to an instruction of the CPU 2, and outputs the signal to the data line SDDAT [3:0] .

The SD device 5 comprises, for example, a NAND flash memory 50, a controller 60 for controlling the operation of the flash memory 50, and a clock terminal, a command terminal and data terminal which are connected to the clock line, command line and 4-bit data line of the SD I/F 34.

FIG. 2 shows an example of the memory map of the SD device 5. The NAND flash memory 50 comprises a user area 51, a boot code area 52, a protection area 53 and a system area 54.

The user area 51 is an area which can freely be accessed and used by the host apparatus 1 and the user of the host apparatus 1. The user area 51 stores arbitrary data such as various data and a program necessary for the operation of the host apparatus. The data in the user area 51 is managed, for example, by a file allocation table (FAT) .

The protection area 53 stores, for example, data which is accessible by only the specified host apparatus 1. The user of the host apparatus 1 can access the protection area 53, only in the case where a predetermined condition is satisfied.

The system area 54 is an area which cannot directly be accessed by the host apparatus 1 and the user. The system area 54 is the area that is managed by a controller (not shown) in the SD device. For example, the system area 54 stores control information of the controller, and security information.

The boot code area 52 stores, for example, a boot code 1 and a boot code 2. Each of the boot code 1 and boot code 2 is a set of codes for executing at least a part of the series of processes which need to be executed after the power-on of the host apparatus 1 and before the start of the system (OS) . The boot code 1 and boot code 2 are identical. For example, in the case where a defect has occurred in the boot code 1, the boot code 2 is used.

The data in the boot code area 52 is not managed by the file system. In the boot code area 52, for example, boot codes are stored in the order from a page of a lower address toward a page of an upper address. After power-on, the controller 60 successively reads the boot code 1 in the boot code area 52 in the order from a lower address toward an upper address, in accordance with a quick boot request (to be described later) which is delivered from the host controller 3, and transfers the boot code 1 to the host controller 3. (Quick boot operation)

Next, the quick boot operation according to the present embodiment is described.

If the host apparatus 1 is powered on, the CPU 2 activates the host controller 3. Further, upon the power-on, the CPU 2 delivers an instruction to the host controller 3. This instruction is an activation instruction for starting a quick boot operation which is preset in the CPU 2, and this activation instruction is composed of, for example, an instruction code which is indicative of a quick boot, and data storage addresses. The activation instruction is delivered to the SD I/F 34 via the host I/F 31 and DMA controller 32 of the host controller 3. According to the activation instruction, the CMD generator 35 of the SD I/F 34 outputs a command CMDO which instructs a data read operation, and the DAT generator 36 outputs a specific signal .

FIG. 3 shows the CMDO and the specific signal, which are generated according to the activation instruction. Specifically, on the falling edge of the clock signal SDCLK, the CMD generator 35 generates a command CMDO and delivers the command CMDO to the command line. A start bit "S" and an end bit "E" are added before and after the command CMDO. The DAT generator 36 generates a specific signal which is set at a low level in accordance with a period of the command CMDO, and delivers this signal to a data line SDDATO. Specifically, the specific signal of the data line SDDATO is set at a low level in accordance with the output of the command CMDO, and is restored to the high level at the same time as the end bit of the command CMDO. This becomes the quick boot request to the SD device 5.

Responding to the quick boot request, the controller 60 of the SD device 5 reads, for example, the boot code 1 from the boot code area 52 of the flash memory 50, and outputs the boot code 1 to the data line SDDAT 0-3 within one second. The read boot code 1 is transferred to the host controller 3 in a 4-bit mode in association with each data of, e.g. 512 bytes + CRC (cyclic redundancy check code) .

The DMA controller 32 of the host controller 3 transfers the boot code 1, which has been transferred to the buffer 33 via the SD I/F 34, to the system memory 4 via the host I/F 31. In other words, the DMA controller 32 transfers the boot code 1 in the buffer 33 to the system memory 4 in accordance with the activation instruction which is delivered from the CPU 2. The CPU 2 executes the boot code 1 that has been transferred to the system memory 4, and activates the host apparatus.

FIG. 4 is a flow chart illustrating an access method of the boot code area 52 by the controller 60.

As has been described above, the boot code area 52 stores the identical boot codes 1 and 2. Responding to the quick boot request, the controller 60 first reads the boot code 1 (STl) . It is then determined whether the read of the boot code 1 is successful or not (ST2) . If the read of the boot code 1 is successful, the process is normally finished.

On the other hand, if the read of the boot code 1 has failed, the boot code 2 is read (ST3) . It is then determined whether the read of the boot code 2 is successful or not (ST4) . If the read of the boot code 2 is successful, the normal boot code 2 is copied to the memory area of the boot code 1. As a result, the boot code 1 is overwritten with the boot code 2. Thereby, the normal boot code is first accessed.

FIG. 5 shows an example of application of the present embodiment. FIG. 5 shows a mobile terminal apparatus 10 which is, for instance, a mobile phone. The mobile terminal apparatus 10 incorporates within the main body thereof the host apparatus 1 including the CPU 2, system memory 4 and host controller 3 according to the above-described embodiment. In addition, the electronic device 5 according to the embodiment is embedded in the mobile terminal apparatus 10. Furthermore, an electronic device 11 including a NAND flash memory is attachable to the mobile terminal apparatus 10.

The mobile terminal apparatus is not limited to the mobile phone, and may be a personal computer, a portable music recording/playback apparatus, etc.

According to the above-described embodiment, when power is turned on, the host controller 3 generates a command and a specific signal in accordance with an instruction from the CPU 2. The SD device 5 reads the boot code on the basis of the command and specific signal. Subsequently, the boot code is transferred to the system memory 4 by the DMA controller 32 of the host controller 3. Thus, unlike the prior art, a system ROM for storing a boot loader is needless. Therefore, the manufacturing cost of the host apparatus 1 can be reduced.

Furthermore, the SD device 5 stores the identical boot codes 1 and 2. If a defect occurs in the boot code 1, the boot code 2 can be read. Therefore, the boot operation can surely be executed, and the lifetime of the host apparatus 1 can be increased.

Besides, if a defect occurs in the boot code 1, the boot code 2 is copied to the memory area of the boot code 1. Thus, since the normal boot code is first accessed, the speed of the boot operation can be increased.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Industrial Applicability

The present invention is used, for example, in a mobile terminal in which a flash memory is mounted.