Patent ID: 8437955
Filing Date: 2013-05-07
Classification: G01C,G09B

Abstract:
1. A map drawing device comprising: an arithmetic processing unit that operates according to a map drawing program and outputs an address of map data to be drawn; an address difference detection circuit that makes comparison of each address of map data output one by one from the arithmetic processing unit, and determines whether or not to output a transfer start trigger signal to a data transfer control unit; and a data transfer control unit that directly transfers the map data with the address instructed by the arithmetic processing unit to a video memory from a map data storage medium, based on the transfer start trigger signal output from the address difference detection circuit, wherein the address difference detection circuit includes: a first address register that stores the address output from the arithmetic processing unit; a second address register that is rewritten when the address of map data has been changed; and an address mismatch detection circuit that calculates a difference between the address stored in the first address register and an address stored in the second address register, and prevents output of the transfer start trigger signal to the data transfer control unit when the addresses match.