Mitsubishi Denki Kabushiki Kaisha

Renesas Electronics Corporation

Tetsuya Ooba

Naohisa Uehara

Masahiko Katayama

Masayoshi Ono

Masato Sumida

A semiconductor device capable of suppressing reduction in performance is provided. The semiconductor device includes: a processor; a DR processor including a DMA controller; a system memory; an internal bus to which the processor, the DR processor, and the system memory are connected; and a bus arbiter connected to the processor and the DR processor, the bus arbiter executing arbitration between access to the system memory by the processor and access to the system memory by the DMA controller in accordance with a predetermined priority order. Here, the DR processor includes a frequency circuit determining a frequency at which the access to the system memory by the DMA controller is not permitted by the arbitration made by the bus arbiter.

Semiconductor device and control method of the same

A communication apparatus for a vehicle achieves reduction in size and cost of a portable unit by making unnecessary an oscillation circuit and a battery in the portable unit. The apparatus is provided with an on-board unit installed on the vehicle and a portable unit carried by a user of the vehicle. A response signal is sent from the portable unit to the on-board unit in response to a signal transmitted from the on-board unit. The portable unit includes a power generation circuit for supplying electric power to circuits in the portable unit by a power generation radio wave sent from the on-board unit, and the on-board unit sends a communication signal after sending the power generation radio wave.

Communication apparatus for vehicle

A communication apparatus for a vehicle can achieve an inexpensive technique for determining whether a portable unit exists inside or outside the vehicle without depending upon LF band radio waves through contactless communication using high frequency band radio waves by separating a reader function of a reader/writer into the portable unit and an on-board unit. The apparatus includes at least one ID transmitter installed on a vehicle and sends a transmitter ID possessed by itself in response to reception of a radio wave, an on-board unit installed on the vehicle for radiating a radio wave to the ID transmitter, a portable unit that receives the transmitter ID sent by the ID transmitter, and an ID communication section for sending the transmitter ID from the portable unitto the on-board unit. The on-board unit determines the position of the portable unit based on the transmitter ID received from the portable unit.

Growing community of inventors

Tokyo, Japan

Tetsuya Ooba