Why Can’t I Use the PMOD/A31/PIO Pin in FastChip 2.2.0?

Beginning with FastChip 2.2.0, the PMOD/A31/PIO pin in an E5 design is marked as a reserved pin.

This change was made because of a potential problem during initialization. If a signal is driven into PMOD/A31/PIO, then the logic value controls whether the E5 device initializes in parallel or serial mode at power-up. If you carefully control the signal on PMOD/A31/PIO, then you can avoid this potential problem. For example, if PMOD/A31/PIO is always an output from the E5 device, you will never encounter this problem.

This change to FastChip, however, may affect older designs created with previous versions of FastChip. You may not be able to Bind a design using a pre-assigned PIO. If this is the case and you need the PMOD/A31/PIO pin for you application, please create a file called triscend.props in your FastChip installation directory. By default, FastChip is installed under C:\Triscend\FastChip.

In the triscend.props file, add the following line.

triscend.IO.useConditionallyRecoverablePin=true

After saving the file, re-run Bind. This directive in the triscend.props file instructs Bind that it may use the PMOD/A31/PIO pin.

FastChip Version: 2.2.0

This solution may or may not apply to other versions of the FastChip development system.