Why can't I access the Intel® Arria® 10 device over JTAG if it is powered up with nCONFIG held low?

Description

In Intel® Arria® 10 devices, the JTAG circuit will not be enabled until nSTATUS goes high after power-up.

Hence if nCONFIG is held low when powering up the device,  nSTATUS will be held low, and the JTAG circuit will not be enabled until after nCONFIG is driven high and nSTATUS is released.

Otherwise, only the BYPASS instruction will be supported, and access over JTAG, including boundary scan testing, will fail.

Resolution

It is recommended to power-up Intel® Arria® 10 devices with nCONFIG pulled high.