METHOD FOR CONTROLLING ACCESS OF EXTERNAL MEMORY OF DIGITAL SIGNAL PROCESSOR

摘要

PURPOSE: A method for controlling an access of an external memory of a digital signal processor is provided to reduce the load by reducing the time for enabling a CPU to process a holding/releasing of a DSP in case that the CPU accesses to an external memory connected to a specific DSP(Digital Signal Processor). CONSTITUTION: A CPU selects a DSP for recording/reading data among a plurality of external memory of the DSP. After that, the CPU outputs a chip selection signal. A holding signal is generated based on a DSP selection signal and the chip selection signal The holding of the DSP is performed. The CPU performs a reading/recording access to the external memory of the DSP. The CPU releases a holding state of the DSP. A DSP hold control unit of a PLD(Programmable Logic Device) performs a logic process of the DSP selection signal and the ship selection signal. After that, a holding signal of the DSP is generated. The DSP transmits a whole response signal to the PLD. An external bus and a control signal are changed into high-impedance signals.