| 摘要 |
PROBLEM TO BE SOLVED: To correctly recognize connection of host equipment to a USB port, even under data rewriting in a nonvolatile memory. SOLUTION: A USB interruption processing program is stored in a flash ROM together with other data. A USB interruption mask is set when updating a data in the flash ROM (step S103), and writing into the flash ROM is carried out under the condition of prohibiting the interruption resulting from equipment connection to the USB port (step S104-S111). An interruption request flag is forcibly set after the writing (step S112), and the interruption mask is released. USB interruption processing is executed thereby irrespective of the presence of an interruption factor, and the USB host equipment connected during write processing is recognized by this manner. COPYRIGHT: (C)2009,JPO&INPIT
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