Running the Connection Test

Having set up the basic structure of the board, we can now start testing it. The first test we will add is the Connection Test. When the Connection Test is run, it may report further errors that are not identified by the learn connection tool. Typically, the cause of an error in the Connection Test at this stage will be due to a missing constant pin definition or a boundary scan enabled pin that has been tied to a power or ground net.

Connection Test is automatically added to the list of tests in a new project so there is little that needs doing.

There should be a single error reported by Connection Test at this stage - net U1.IO24 is stuck low.

The Schematic Viewer will show U1.24 with a circle around the pin, and will show that the pin is on a net called DECODE.

From the schematic we can see that the DECODE net is driven by a logic block that cannot be disabled. When setting up the constant pins in the previous step we missed one of them - this is how connection test typically shows up such misconfigurations, or unknown connections.

Now that the board has been created we can fix this setup mistake by adding a constant pin in the usual way from within XJDeveloper: