Visible to Intel only — GUID: sss1410934205492
Ixiasoft
Visible to Intel only — GUID: sss1410934205492
Ixiasoft
Verification During JTAG Secure Mode
Non-mandatory JTAG instructions are disabled when the tamper protection bit is enabled in 28-nm FPGAs. When executing KEY_VERIFY during the tamper protection bit is programmed, TDI points to the BYPASS register. Due to this, executing the KEY_VERIFY instruction when the tamper protection bit has been set results in 0x0 (hex) being returned.
To check if the tamper protection bit has been programmed in a device, shift a user defined pattern in when executing the KEY_VERIFY instruction and check that the TDO pattern received has a 0 shifted in.
In 20-nm FPGAs, KEY_VERIFY instruction can be executed during JTAG Secure mode. To perform verification during JTAG secure mode for 20-nm FPGAs, you can expect 0x0 (hex) value being returned when executing USERCODE instruction.