Configuration and Mode Setting - Configuration and Mode Setting - UG860

Spartan UltraScale+ FPGAs Configuration User Guide (UG860)
Document_ID
UG860
Release_Date
2026-07-27
Revision
v1.3 English

The Boundary Scan Description Language (BSDL) file is a boundary-scan model of an unconfigured device. Boundary-scan tests based on the BSDL file must be applied to an unconfigured and unsecured device.

For JTAG boundary-scan test, the configuration mode pins must be set to the JTAG configuration mode (M[2:0]=101). To accommodate JTAG boundary-scan test, the PCB design must allow for the M[2:0] pins to be changed between the JTAG mode for JTAG boundary-scan test and the primary configuration mode for normal system configuration and operation. If the device is set to JTAG configuration mode, the device remains unconfigured after power-on initialization (unless a configuration PDI is delivered via JTAG) and then JTAG boundary-scan tests can be applied to the unconfigured device.

Important: In SU10P, SU25P, SU35P devices, JTAG boundary-scan is only accessible after power-up initialization when the device is in JTAG configuration mode and is unsecured. For other configuration modes, the JTAG security gate (default TAP_SECURITY.SEC_GATE register setting) blocks JTAG boundary-scan access in these devices. In unsecured devices, the security gate can be released by applying a JPROG instruction followed by a BYPASS instruction and waiting for 100 ms, which internally resets the device to JTAG configuration mode.