U21 marked no-pop, means no ESPI (or LPC) connectivity

[jk-ozlabs]

The current design has U21 - the ESPI level translator - marked as DNP, and is not populated on the board I have here.

This means that there's no connectivity to the ESPI pins on the DC-SCI connector.

However: on POWER platforms, we're using these pins for the LPC interface rather than ESPI. Also, the LPC bus here is expecting 3.3V signalling anyway. For a future design, it would be nice to be able to modify the VREF_A signal to provide either 1.8 or 3.3V on the DC-SCI side of the translator (say, by briding pads to either VCC1V8 or VCC3V3.

Consequently, for the POWER platform we're using here, we have worked-around this by bridging the 8 channels of the translator.