Abstract: Serial communication with a bit rate close to a required bit rate can be performed, regardless of the frequency of an operation clock. A semiconductor device includes a serial communication interface that operates according to a certain operation clock. The serial communication interface is provided with a baud rate generator that generates a basic clock for counting the operation clock to define the unit transfer time based on the count, and a transmission/reception controller for performing control of transmission and reception according to the generated basic clock. Further, the serial communication interface is provided with a bit rate modulator capable of realizing a desired bit rate by partially masking supply of the operation clock to the baud rate generator, and thereby serial communication with a bit rate close to a required bit rate is realized.

Abstract: An object of the present invention is to achieve fast data processing. A unit (FF) is included for selecting whether a central processing unit (CPU) performs instruction reading in units of 16 bits (a first word length) or in units of 32 bits (a second word length). Depending on whether instruction reading is performed in units of 16 bits or 32 bits, increment values (+2 and +4) by which a program counter (PC) is incremented are switched. Data reading or writing is performed in units of a given data length irrespective of the selecting unit. When the CPU issues a request for instruction reading in units of 16 bits or 32 bits or for data reading or writing, a bus control unit performs reading or writing a predetermined number of times according to a bus width designated for a resource located at an address specified in the request. The bus control unit causes the CPU to wait until an instruction of 16 or 32 bits long (read data) requested by the CPU gets ready.

Abstract: An apparatus and method for selecting whether a central processing unit (CPU) performs instruction reading in units of 16 bits (a first word length) or in units of 32 bits (a second word length). Depending on whether instruction reading is performed in units of 16 bits or 32 bits, increment values (+2 and +4) by which a program counter (PC) is incremented are switched. Data reading or writing is performed in units of a given data length irrespective of the selecting unit. When the CPU issues a request for instruction reading in units of 16 bits or 32 bits or for data reading or writing, a bus control unit performs reading or writing a predetermined number of times according to a bus width designated for a resource located at an address specified in the request.

Abstract: The present invention realizes improvement in security in the case where a nonvolatile memory device which can be read/written by random access is mounted as a memory for storing both of a program and data. In a microcomputer including: a CPU enabling a computing process based on a preset program; and a nonvolatile memory device which can be read/written by random access of the CPU, the nonvolatile memory device includes, in a part of its memory area, an area in which nonvolatile holding is invalid. By using the area as an area for storing secret data to be held, the secret data to be held is prevented from being nonvolatile-held in the nonvolatile memory device. Thus, improvement in security is achieved.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: Error recovery processing is performed to minimize the influence of malfunction when an error is detected. When an error occurs in a normal program execution state, control branches to a predetermined error handling routine shown by exceptional handling vectors or the like. While executing the instruction that writes zero to a timer counter in an interval not extending an overflow cycle, the error handling routine of a CPU performs processing for inhibiting a fatal operation in accordance with a control target system. An example of inhibiting a fatal operation is to deactivate output signals of a microcomputer. Upon completion of the error handling, the monitoring timer is stopped, and the processing of the CPU is changed to the normal reset processing routine.

Abstract: A data processing apparatus (1) can implement the execution of a virtual machine instruction based on an execution routine specified by the native instruction of a CPU (2) and has an address converting unit (3) capable of sequentially converting an address output from the CPU into the address of the native instruction by utilizing the address of a prepared execution routine in response to the application of a prescribed condition. The address converting unit reads a virtual machine instruction to be executed next and prepares the address of an execution routine corresponding thereto in parallel with the execution of the execution routine by the CPU based on the address of the native instruction which is sequentially converted. Accordingly, it is possible to reduce the overhead of a processing of loading the virtual machine instruction and a processing of executing an instruction in accordance with the execution routine which is caused by an address calculation processing based on the load processing.

Abstract: A single chip type microcomputer includes at least a central processing unit (CPU), a random-access memory (RAM), a mask read-only memory (CPU) and an electrically writable ROM such as an electrically erasable and programmable read-only memory (EEPROM). The electrically writable ROM stores both the user program and data to be preserved. The microcomputer includes further a memory for storing a write control program for controlling the write operation to the writable ROM, and the electrically writable ROM and the memory are disposed at mutually different address positions on the address space of CPU. The proportion of size of the user program region and the data region in the writable ROM can be selected in a free proportion.

Abstract: A microcomputer is provided with a data-transfer unit such as a DMA (direct memory access) controller for controlling a transfer of data through an external bus. Used in an access to an external device controlled by the data-transfer unit, a bus-interface means of the microcomputer includes a buffer-register means which can be specified as either a source location or a destination location of a data transfer. Thus, an internal-bus master such as a CPU employed in the microcomputer is capable of reading out information such as a packet command from the buffer-register means at a high speed through an internal bus without using the external bus and, hence, capable of carrying out an operation reflecting a transfer control condition specified by the packet command.

Abstract: A microcomputer is provided with a data-transfer unit such as a DMA (direct memory access) controller for controlling a transfer of data through an external bus. Used in an access to an external device controlled by the data-transfer unit, a bus-interface means of the microcomputer includes a buffer-register means which can be specified as either a source location or a destination location of a data transfer. Thus, an internal-bus master such as a CPU employed in the microcomputer is capable of reading out information such as a packet command from the buffer-register means at a high speed through an internal bus without using the external bus and, hence, capable of carrying out an operation reflecting a transfer control condition specified by the packet command.

Abstract: A microcomputer is provided with a data-transfer unit such as a DMA (direct memory access) controller for controlling a transfer of data through an external bus. Used in an access to an external device controlled by the data-transfer unit, a bus-interface means of the microcomputer includes a buffer-register means which can be specified as either a source location or a destination location of a data transfer. Thus, an internal-bus master such as a CPU employed in the microcomputer is capable of reading out information such as a packet command from the buffer-register means at a high speed through an internal bus without using the external bus and, hence, capable of carrying out an operation reflecting a transfer control condition specified by the packet command.

Abstract: A single chip type microcomputer includes at least a central processing unit (CPU), a random-access memory (RAM), a mask read-only memory (CPU) and an electrically writable ROM such as an electrically erasable and programmable read-only memory (EEP-ROM). The electrically writable ROM stores both the user program and data to be preserved. The microcomputer includes further a memory for storing a write control program for controlling the write operation to the writable ROM, and the electrically writable ROM and the memory are disposed at mutually different address positions on the address space of CPU. The proportion of size of the user program region and the data region in the writable ROM can be selected in a free proportion.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: A microcomputer is provided with a data-transfer unit such as a DMA (direct memory access) controller for controlling a transfer of data through an external bus. Used in an access to an external device controlled by the data-transfer unit, a bus-interface means of the microcomputer includes a buffer-register means which can be specified as either a source location or a destination location of a data transfer. Thus, an internal-bus master such as a CPU employed in the microcomputer is capable of reading out information such as a packet command from the buffer-register means at a high speed through an internal bus without using the external bus and, hence, capable of carrying out an operation reflecting a transfer control condition specified by the packet command.

Abstract: There is provided a data processing apparatus capable of increasing a number of general purpose registers while maintaining upper compatibility. Register designating information for designating a register is divided in two portions. The two portions are arranged in separate basic units on the basic units of an instruction code. When one instruction code is made ignorable and the ignorable instruction code is ignored, a control unit (CONT) executes register selecting operation by implicitly assuming predetermined register designating information. Thereby, when only a general purpose register (existing general purpose register) capable of being designated implicitly is used, the ignorable instruction code can be ignored and accordingly, the instruction codes are not increased. When an at least conventionally equivalent general purpose register is used, a conventionally equivalent instruction code may be used. By preventing the instruction codes from increasing, processing speed is not reduced.

Abstract: An object of the present invention is to achieve fast data processing. A unit (FF) is included for selecting whether a central processing unit (CPU) performs instruction reading in units of 16 bits (a first word length) or in units of 32 bits (a second word length). Depending on whether instruction reading is performed in units of 16 bits or 32 bits, increment values (+2 and +4) by which a program counter (PC) is incremented are switched. Data reading or writing is performed in units of a given data length irrespective of the selecting unit. When the CPU issues a request for instruction reading in units of 16 bits or 32 bits or for data reading or writing, a bus control unit performs reading or writing a predetermined number of times according to a bus width designated for a resource located at an address specified in the request. The bus control unit causes the CPU to wait until an instruction of 16 or 32 bits long (read data) requested by the CPU gets ready.