You can set the P2.1 latch bit to ensure you can use the pin as input on the microcontroller using the instruction SETB P2.1.

In my discussion of the AGND, DGND, DVCC pins I am referring to the ADE7756 chip. This chip has a AVDD, AGND pin pair for the analog section and a DVDD, DGND pin pair for the digital section. Someplace on your board DGND and AGND must be connected together to keep these two pins at eqipotential.

Michael Karas