| 摘要 |
PURPOSE: A device for protecting data in testing a code ROM is provided to prevent other person who does not know a password from flowing data of a code ROM of a micro controller to an exterior by prevent other person who does not know the password from using the data although the data are flown out to an exterior. CONSTITUTION: A first encoding unit(200) encodes and transmits data. A second encoding unit(300) creates a read enable signal(ROMReadEn). An output unit(400) dumps the encoded data to an exterior by responding to the read enable signal(ROMReadEn). An MISR(Multiple Input Signature Register) unit(220) synchronizes the data from the code ROM(100) with a clock, receives the synchronized data, and compresses the data. An initialization unit supplies an initial value to the MISR unit(220) by responding to a test enable signal(TestEn) and a reset signal(Reset). A control state machine(320) creates a control signal for a ROM test operation by responding to a test enable signal(TestEn) and a clock signal(CLK). The other MISR unit(340) responses a control signal, receives code data, compresses the data, and outputs the data. An initialization unit supplies an initial value to the other MISR unit(340) by responding to a test enable signal(TestEn) and a reset signal(Reset). A comparison unit(380) compares the value being output from the other MISR unit(340) with an expected value, and outputs the read enable signal(ROMReadEn).
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