Why does my source get set to 0 unexpectedly in In-System Sources and Probes?

Description

Due to the problem in the Quartus® II software versions 12.1 and earlier, In-System Sources and Probes may unexpectedly set your source to 0. This may occur in either of the following situations:

• Opening the In-System Sources and Probes Editor without having your Quartus II project open first
• On the In-System Sources and Probes Editor Edit menu, selecting Recreate Instances From JTAG Device

When this error occurs, you may see the following message in the System message tab:

Info (261000): write_source_data -instance_index 0 -value 0 -value_in_hex

Resolution

To work around this problem, perform either of the following actions:

• Open the Quartus II project before opening the In-System Sources and Probes Editor
• Save the setup in a Sources and Probes File (.spf), and load the Editor by opening that .spf

This problem is scheduled to be fixed in a future release of the Quartus II software.