Setting debug interface voltage levels (Vref)
The voltage levels for the debug interface are configured within winIDEA via the CPU Options dialog.
Solution
Make sure Vref is selected for Debug I/O levels, otherwise, the debug session fails or may behave unpredictably.
1. Open Hardware | CPU Options | Hardware.
2. Select the Vref option.
The debugger also provides the option Check Vref on startup. This option is checked by default and results in the debugger checking the voltage automatically when establishing initial debug connection to the target CPU.
If the debugger can't connect to the CPU, double check that the CPU power supply voltage is present at the target LPD debug connector or JTAG/Nexus debug connector at the belonging pin. Either measure the voltage directly on the belonging debug connector pin with voltmeter or open the Measurement Plugin by clicking View | Measurement and check the Vref value, which displays measured reference voltage by the BlueBox or use the Check Vref on startup option mentioned above.
winIDEA 9.17.182 and older:
The Vref option is located in Hardware | Emulation Options | Hardware.