Fujitsu Corporation

Yukihiro Ozawa

Seiji Suetake

Satoshi Matsui

Yoshihiko Koike

Norihiro Nakatsuhama

Akira Miho

Osamu Tago

An abnormality detection device detects an abnormality in a communication bus. The abnormality detection device comprises a timer counter connected to the communication bus so as to measure a time during which a signal having a first logical level is transmitted in the communication bus, and a comparator outputting an abnormality detection signal indicating an abnormality in the communication bus when the time measured by the timer counter surpasses a threshold value.

Abnormality detection device for detecting an abnormality in a communication bus

A circuit for changing clocks includes a clock generating circuit which generates an output clock signal by controlling a frequency of an original clock signal, and a control circuit which controls the clock generating circuit in response to an operation mode change signal indicative of a change from a first operation mode to a second operation mode of an external circuit operating based on the output clock signal, thereby changing the output clock signal from a first frequency corresponding to the first operation mode to an intervening frequency and then from the intervening frequency to a second frequency corresponding to the second operation mode, the intervening frequency having a frequency between the first frequency and the third frequency.

Clock shift circuit for gradual frequency change

An semiconductor device includes a voltage-decreasing regulator which converts a source voltage into an output voltage in accordance with a control signal, the regulator supplying the output voltage to an internal module via a power line. An analog-to-digital converter converts the output voltage received from the power line, into an output signal indicating a value of the output voltage. A voltage monitoring circuit has a control register holding a value predetermined for a selected operational mode. The voltage monitoring circuit generates the control signal based on a result of comparison between the value indicated by the output signal of the converter and the value held by the control register, and outputs the control signal to the regulator so that the regulator supplies the output voltage, adjusted to an optimal output voltage for the selected operational mode by the control signal, to the internal module.

Semiconductor device including a voltage monitoring circuit

A controller for effecting a serial data communication and a system including the controller in a transmitting side and/or a receiving side thereof. The controller includes a unit for serially storing data, a unit for arbitrarily setting a bit length of data to be an object of the serial data communication, a unit for controlling a first clock to synchronize with the serial data in a serial data communication duration, and controlling a second clock to synchronize with the serial data in a duration, and a unit for indicating a permission or inhibition of the serial data communication according to whether the counted value of the first clock is within or out of a value defined by the arbitrarily set bit length. By taking data of the arbitrarily set bit length out of the serial data stored in the memory unit when the serial data communication duration is indicated, to effect the serial data communication, and inhibiting the serial data communication when the duration is indicated, it is possible to effect a serial data communication of arbitrary bit length and thus reduce the communication time.

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Kawasaki, Japan

Yukihiro Ozawa