Security

The security bit allows the entire chip to be locked from external JTAG or other debug access for code security. Once set, the only way to clear the security bit is through the Chip Erase command.

Figure 1. Security Page

To check the state of the security bit, press the Read button on the Security page of the programming dialog. The value should now read Cleared or Set. Set means that the security bit is set and Cleared that it is not set. If the Auto Read checkbox is ticked off, the Read operation will automatically be performed when opening the Security page.

To set the security bit, press the Set button on the Security page of the programming dialog. Now the device is locked for all further JTAG or aWire access except for the Chip Erase command.

Locked Device

When the security bit is set, the device is locked for most external debug access. Attempts to program or read any memories or fuses will cause an error message to appear.

Figure 2. Security Bit Error

To unset the security bit, issue the Chip Erase command. Do this from the Memories page. See Memories.